Alaska Log Building Constrution Guide.pdf

8/13/2019 Alaska Log Building Constrution Guide.pdf

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Introduction

TheAlaska Log Building Construc-tion Guide is written to help logbuilders, owner-builders, contrac-tors, architects, engineers, andbuilding manufacturers build loghomes that meet the State of AlaskaBuilding Energy Efficiency Stan-dards (BEES) (see Appendix A).

This book contains useful

information for anyone interestedin building or renovating energy-efficient, quality log structures inAlaska. A number of basic proce-dures and techniques are describedin detail to help even the novice logbuilder get started building his orher first log project. Building anenergy-efficient log home requiresthe highest level of craftsmanshipto meet modern standards of

airtightness, indoor air quality,safety, comfort, and durability.

Disclaimer

Alaska Housing Finance Corpora-tion, its agents, and the authors ofthis book assume no responsibilityfor the use of information in thisbook by anyone. All design details,methods of construction, andstructural systems should bechecked out by a professional toassure compliance with codes andregulations. This book is not in-tended to supersede either local ornational building codes.

Energy-efficientLog Homes

From the south slope of the BrooksRange, which more or less definesthe northern limit of the borealforest, to the rain forests of thesouthern panhandle, Alaska isblessed with an abundance of treessuitable for building log homes. Theromantic image of a log cabin in the

woods is slowly being replacedwith log homes hand-crafted frommassive logs up to two feet indiameter and fitted so tightly thateven after several years of settle-ment and shrinking, you canteasily slide a knife blade betweenthe logs.

In the introduction to the eighthedition of Building With Logs, authorand noted Canadian log builder and

teacher B. Allan Mackie invites thereader to take a closer look at thephysical properties of trees. Henotes that the body of the tree iscomposed of hollow cells packedtightly together. Under a micro-scope, they look like a honey-comb. When the tree isfelled and the vitalfluids have dried,these tiny air

pockets seal,becoming analmost perfectlyinsulated build-ing material. . ..The tree as it existsnaturally is an almostperfect building material.

Chapter 1Introduction

Cross section of a treein magnification.


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Big Logs

In the case of massive logs, R-value,the resistance to heat flow, is not theonly property relating to energyuse. Logs with a good southernexposure will store heat from the

sun during the day and slowlyrelease that heat at night. The cyclerepeats until fall when you have tostart adding heat from your woodstove or furnace. One or two short,hot firings a day of a good airtightwood stove during the winterheating season will heat a well-builtmodern log home. The objective isto keep the mass of the logs fromcooling to below a thermostat

setting for the fossil-fuel-firedfurnace or boiler.

As you travel north in Alaska,the trees tend to get smaller and

eventually reach a lower limit to thediameter of logs that will meet theprescriptive R-value requirementsof State of Alaska Building EnergyEfficiency Standards. For example,if the logs average less than 13" indiameter in southeast Alaska, thebuilder will have to increase theefficiency levels of other compo-nents of the building system anduse the building budget method ofcompliance, which requires a HOT-2000 or AkWarm computer energyuse calculation, or the energy ratedmethod to comply with BEES (SeeAppendix A).

AkWarm is an energy analysissoftware program used by theAlaska Housing Finance Corpora-tion (AHFC) to perform energyratings on proposed house plans oron old and new houses. Hot 2000 is

R-0

R-5

R-10

R-15

R-20

R-25

R-30

R-35

R-40

4% MOISTURE = APPROX. R-2.00 PER INCH *

8% MOISTURE = APPROX. R-1.50 PER INCH *

12% MOISTURE = APPROX. R-1.25 PER INCH

20"18"16"14"12"10"8"6"DIAMETER OF WHITE SPRUCE LOGS

* extrapolated from Carlson, Building a Log House in Alaska (see Appendix D,

References and Bibliography)


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an energy analysis software pro-gram that was developed for theCanadian R-2000 Program and isalso used by the Alaska CraftsmanHome Program to qualify a homefor meeting their standards ofenergy efficiency.

Alaska white spruce has athermal resistance of about R-1.25per inch at 12% moisture content.Oven dry white spruce has athermal resistance of 1.47 to 2.04per inch. Log walls in the interior ofAlaska may have a higher R-valuebecause of the extreme dryness ofthe air during prolonged subzeroweather (Carlson, Building a LogHouse in Alaskasee Appendix D).

AkWarm assigns defaultR-values for logs that do not ex-actly match the numbers listedabove. The default R-value per inchin AkWarm steadily decreases asthe size of the logs increases.AkWarm assumes R-values as inTable 1 below.

Since the moisture content oflogs varies, AkWarm does not

consider moisture content in as-signing these default numbers. Ifyour logs are especially dry, yourenergy rater might be able tooverride the default R-values andinput slightly higher R-values.

Small Logs

As we noted above, small diameterlogs and 6-inch and 8-inch three-sided logs will not comply with theprescriptive standard unless theyare furred in (or out) and insulated

and vapor barriered like a framewall. Unless you are just building asimple cabin, 6 or 8-inch three-sidedlogs usually just end up being veryheavy and expensive siding. If youare building a house to meet BEES,three-sided logs may be a poorchoice of materials. It might bebetter to mill the trees into framingmaterials or post and beam compo-nents and log siding or bevel siding.

It is, however, quite possible touse the building budget method orthe energy rated method to scoreenough points to qualify a 6-inch or8-inch log wall for four-star-plusand five-star ratings. (See AppendixC, Sample Energy Ratings for LogHomes.) This can be accomplishedwith a thoughtful application ofinsulation to the foundation or floorand a highly insulated roof, energyefficient windows oriented to thesun, and efficient space heating. Thelogs must be especially air tight andthe ventilation system must complywith section 2.5 of BEES (Appen-dix A).

Table 1R-value Assumed

Log Size R-value per inch by AkWarm

6-inch R-1.27 R-7.68-inch R-1.23 R-9.85

10-inch R-1.21 R-12.112-inch R-1.2 R-14.35

14-inch R-1.19 R-16.616-inch R-1.18 R-18.85

18-inch R-1.17 R-21.120-inch R-1.17 R-23.35


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Problems

The first mistake that many loghome builders make is buildinga permanent structure on atemporary foundation. When thefoundation fails, the house willrapidly self-destruct. Differentialsettlement caused by meltingpermafrost, seasonal frost heaving,and flooding is the single most

destructive problem in Alaskabuildings.A close second is poor moisture

control, which may take only a littlelonger to destroy a log housethrough the natural decay process.Damp wood will be attacked byrapidly growing colonies of mold,mildew, and mushrooms, pro-grammed to return the logs tocompost on the forest floor. The

cardinal rule of log home longevityis to keep it dry.

GULF OF ALASKA

CHUCK

CHISE

A

BEAUFORTSEA

BERING

SEA

NOME FAIRBANKSRUS

SIA

UNITE

DSTA

TES

KOTZEBUE

BARROW

Permafrost

In AlaskaContinuous Permafrost

Discontinuous

Permafrost

Discontinuous

Permafrost

Generally Free

from Permafrost

BETHEL

MCGRATH

ANCHORAGEVALDEZ

Continuous

Permafrost

Source: Environmental Atlas of Alaska, 1978

Charles Hartman and Philip Johnson

JUNEAU

Chapter 2Problems and Solutions

From the Ground UpThe most important considerationfor building a foundation for a logstructure is the ground upon whichit sits. A log home may be two tofour times heavier than a compa-rable frame house. The heavier andmore expensive a structure is, themore important it is to have goodsoil information upon which to base

a foundation design. The best wayto determine what kind of ground isunder your proposed log home is tocore drill test holes under thefootprint of the foundation, to atleast 40 feet deep if permafrost ormass ice is possible. At the veryleast, use whatever technology is athand to dig a hole in the ground.Drive a steel rod or dig a hole witha shovel or a backhoe or a cat.


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ice forming

in soil

Non-frost susceptible soilsare soils that drain well, sono water is left to freeze.

This means sand or gravel.

Frost-susceptible soilholds moisture like asponge and swells asthe water turns to ice.

About half of Alaska is underlainwith permafrost. Approximatelyone quarter of the state must con-tend with discontinuous perma-frost, while the remaining quarter isgenerally free of permafrost (seemap on previous page). The U.S.Natural Resources ConservationService may be a good source ofinformation on soils in your area.

Good Soils

Good building soils in Alaska aregenerally non-frost-susceptible(NFS). By this we mean solid rockor free-draining sand and gravelsthat will not hold water and will not

cause frost heaving when theground temperature is belowfreezing. If you are building ongood soils, just about any structur-ally sound foundation that complieswith local building codes andaccepted engineering principles canbe used to support a log home.

If you are building in an areawhere NFS material is not available,you must be especially careful to

control the flow of water off the roofwith ample roof overhangs and raingutters or roof troughs. The groundshould be sloped away from thefoundation in all directions, andsurface runoff should be divertedaround the site with swales, berms,or ditches or a combination of allthree.

Damage from rot

The cardinal rule

of log home

longevity is to

keep it dry.


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N

W

E

S

Permafrost

If you are building in the half ofAlaska with continuous permafrost,you must design a foundation thatwill maintain the below-freezingtemperature of the soil beneath the

house. If you are in the transitionzone of discontinuous permafrost,you must design and build as ifyou are building on frozen ground,unless you know no ice is presentbecause you did a core drilling orother research.

Design

Log house design should begin in

the woods. You need to know whatsort of trees are available. Youshould know the average mid-logdiameters, how long, how straight,how dry, how old, what species.

It is equally important to knowthe building site. When choosingthe best location for the house onyour property, make a drawingshowing the location of the mostbeautiful natural features on the

land. This may be an ancient groveof trees or an interesting rockformation or a meandering troutstream. Whatever it was that madeyou want to buy this land to buildyour home on should not be de-stroyed in the process of buildingthat home. Move back from thestream, avoid getting close to thegrove of trees, and dont bulldozethat fascinating rock outcropping.

The house must also work withthe slope, solar aspect, vegetation,and other natural and man-madefeatures of the landscape. Face thelong side of the house directly atthe midwinter sun for natural lightand passive solar heat. Dont blockthe winter sun with evergreentrees. Birch or aspen will shade the

house in summer and drop theirleaves in the fall, allowing the sunto penetrate deep into the house inthe winter.

South-facing clerestory ordormer windows are preferable toskylights because of potentialglaciering and because a verticalwindow will catch the low wintersun more directly. Take care toavoid overheating with too muchunshaded west-facing glass.

Design the home to fit yourneeds now and in the future. Thinkin terms of growing old along withyour new log home. Your childrenmay choose to live there with theirchildren. Some log homes inScandinavia have been lived incontinuously by succeeding genera-tions for over five hundred years.Design, construct, and maintain alog home so that it will last at leastas long as it took to grow the treesthat are used to build it.

clerestory

shed dormer

gable dormer

winter sun

summersun

Think in terms of

growing old with

your new log

home.


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N

W

E

S

Birch or aspen willshade the house in

summer and drop theirleaves in the fall,

allowing the sun topenetrate deep into

the house in the winter.


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slip joint for log settling

3/4-by-6-inch tongue and groove

perpendicular to purlin

continuous vapor retarder

rigid foam between

2-by-4 nailers

log truss

chimney flashing

tongue-and-groove

ceiling boards

ridgepol

e

purlin

platelog

purlin

ridge pole

king post

roof ventilation

air space2-by-4 nailer over

purlin

plate log

vapor retarder on warm side

chinking

pins (wooden dowel,

rebar, spikes, etc.)

window

spline

partition

wall

rimjoist

rimjoist

floorjoists

lateral groove

wainscot

steel plates for seismic anchor

foundation and footing

subflooring (plywood typical)

floor

closed cellsill seal

air/vapor seal

gable end

eavetie log

king post

truss

post

The parts of a log house


9/8210

Shrinkage

Designing for log construction isnot the same as designing for frameconstruction. You have to allow forsettlement of the horizontal walllogs and gable logs of between 1/2

and 3/4inch per round of logs, de-pending on species and water con-tent. A green 8-foot-tall log wallmay shrink about four to six inchesin height, while a 12-foot-high loggable wall may shrink six to eight

This ridge pole, which rests on ahorizontal log gable, shrank and settledmore than 6 inches and is now crushingthe Sheetrock.

inches or more. All partitions andwalls incorporating vertical postsand stairways must allow forsettlement, and log floor systemsmust account for five or six inchesof settlement.

All window and door framingand vertical support posts andinterior frame walls must allow thelogs to settle down without hangingup and causing gaps to occurbetween log courses. Air leakagethrough poorly fit logs is not onlyone of the greatest sources of heatloss, it is also the major moisturetransport mechanism in a leakyhouse.

Moisture carried by air leakingthrough cracks between the logs orholes in the ceiling vapor retarder

The gap left for settling here is covered with scribe-fit trim.

Unpainted Sheetrock exposed as logssettle. The space above the partition,

which was more than 6 inches whenbuilt, is now 1.5 inches after 12 yearsof settling.


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A slip joint for a partition wall that is parallel to the ridgepole

The dowel is only nailed or glued at the top, and slides down through snug- fitting holes in the plate andblocking as the building settles. A 2-by-6 with both sides beveled at ceiling slope and 1 1/2inches wider than

wall frame is nailed or bolted to the ceiling to attach wide crown molding.The crown molding is only nailedat the top and slides down over the Sheetrock.

blocking

for dowel

slopeofce

iling

wooden dowel

A 2-by-4 stud wall partition slip-joint tokeep walls straight and allow the ceilingto settle. A wooden dowel is used toalign the partition wall with the top

plate, which is attached only at the top.The dowel is run down through snug-fitting holes and braced with additionalblocking.

ceiling

crown molding

beveled 2-by-6nailed to the ceiling

top plate

dowel

blocking

A slip joint for a partition wall that is perpendicular to theridgepole

Sheetrock


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Two ways to attach frame partitions to logwalls and still allow for the settling of the logs

Before the partition walls are

built, the logs are slotted afew inches for the squareSheetrock edge to slide in asthe logs settle.

1

2

Option 1: A stud laid flat against thewall with bolt run through slots longenough to allow for settling. Thismethod uses less wood.

Option 2: Two studs, edge against thewall, spaced apart with small plywoodscraps and bolts through the slot to the

logs. This method can be faster tobuild.

1/2 " plywoodspacers


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will condense into liquid waterwhen it reaches a cool surface. Thiscould lead to rotting logs andglaciers forming on the roof.

In order for a log structure tomeet the airtightness requirementsof the energy standard, it should bebuilt to the highest possible stan-dards of craftsmanship as outlinedin the Log Building Standardsof theCanadian and American LogBuilders Association (Appendix B).

Frost buildup and mildew at a leakaround the ridgepole.

washer

lagbolts

steel plates

An adjustable vertical support post.

mildew

frost

A change in any

part of the sys-

tem will affect

the performance

of the rest of the

system.

The Building as a System

Log buildings must be designed towork as a system and must controlthe flow of heat, air, and moisture inand out of the structure. The build-ing system includes the foundation,floor, log walls, windows, doors,ceiling, heating appliance, ventila-tion system, energy-efficient light-ing, the occupants, and the outsideenvironment. A change in any partof the system will affect the perfor-mance of the rest of the system.

For example: you build a well-crafted home that is so air tight thatthe air inside becomes stale andunheathy, and the wood stovewont draw very well. You mustventilate the house, so you put in a

powerful exhaust fan. Then thewood stove belches smoke back intothe house. Finally, you cut anopening in the wall to provide airfor the wood stove. So now youhave a system and you are in controlof the fresh air in your house.


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If You Want toBorrow Money

All construction should complywith local building codes and theUniform Building Code, the Uni-form Mechanical Code, the Uni-form Plumbing Code, the NationalElectrical Code, and the State ofAlaska Building Energy EfficiencyStandards. If you wish to borrowmoney from the Alaska HousingFinance Corporation and takeadvantage of their many interestrate reduction programs, or if youwant to refinance or sell yourhome, most loan programs require

you to design and build to meetthese codes and standards.

Building your house with an eyetoward complying with the Ameri-cans with Disabilities Act makes thehouse easier for you and yourvisitors to live in as well as makingit easier to eventually sell. Younever know when you might be-come permanently or temporarilydisabled, and its a lot cheaper toincorporate handicap-accessiblefeatures now, when youre building,than to retrofit later. Features likelever handles on doors and faucetsmake life easier even if you're notdisabled.

Top Ten Building Science Rules

1. Heat flows from hot to cold.

2. Heat does not risewarm air rises.

3. Heat is transfered by conduction, convection, and radiation.

4. Heat flow through insulation is slowed by air or other gases.

5. Airtightness prevents major loss of heat.

6. Air flows from higher pressure to lower pressure.

7. Air leakage is the primary moisture transport mechanism.

8. Diffusion is a secondary moisture transport mechanism.

9. Dew point is the temperature at which airborne water vapor condenses intoliquid water. Water vapor is not a problemliquid water is.

10. The vapor retarder should be placed on the warm side of the thermal enve-lope.

Building your

house with an

eye toward com-

plying with the

Americans with

Disabilities Act

makes the house

easier for you

and your visitors

to live in, as well

as making it

easier to eventu-

ally sell.


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Statewide Regions

For the purpose of creatingstatewide building energyefficiency standards, Alaska isdivided into five geographic andclimatic areas (see map below) withminimum standards for eachregion.

This chapter explains the

different ways to meet these stan-dards. The standards themselvesare found in Appendix A.

The traditional sod homes ofthe north and west coasts wereconstructed of driftwood, whalebones, and sod. These structuresoften had a below-grade entrytunnel, with an animal skin door toregulate the flow of ventilation airthrough a hole in the roof. These

structures were often heated with aseal or whale oil lamp and bodyheat.

Chapter 3Meeting the State of Alaskas

Building Energy Efficiency StandardsThe Arctic Slope does not have

any suitable trees from which tobuild log homes. Therefore, thismanual will not include a discus-sion of building with logs in Region5, the North Slope.

Four Ways to ComplyWith the Building Energy

Efficiency StandardThere are four methods of compli-ance with the State of Alaska Build-ing Energy Efficiency Standard:1. The prescriptive method2. The performance method3. The building budget method4. The energy rating method

All of the methods requireminimum standards of balanced

GULF OF ALASKA

CHUCK

CHISE

A*

BEAUFORTSEA

BERING

SEA

NOME

BETHEL

RUS

SIA

UNITE

DSTA

TES

MCGRATH

JUNEAU

BARROW

FAIRBANKS

ANCHORAGE

Region 3

Region 2

Region 1

Region 5

Region 4KOTZEBUE

Statewide Regions


15/8216

mechanical ventilation. (See BEESVentilation Requirements in Ap-pendix A.)

1. Prescriptive Method

The prescriptive method requires

minimum R-values for the ceiling,floor, and walls including windowsand doors (Table 2). This methodrequires the least amount of calcu-lation. You just have to meet orexceed the R-value requirementsfor all of these building compo-nents, comply with all the state-wide mandatory measures outlinedin chapter two of BEES, and meetthe ventilation requirements.

However, meeting the R-valuerequirements for an above-groundwall will be difficult with smallerlogs.

2. Building BudgetMethod

The building budget method setslimits on the total amount of spaceheating energy used by a building.Your house is allowed to lose only acalculated amount of heat persquare foot per hour. This requires acomputer energy use analysis usingeither the HOT-2000 or AkWarmsoftware programs. These softwareprograms are available throughAHFC.

3. Performance Method

The performance method allows the

trade-off of insulation requirementsbetween elements of a particularthermal envelope assembly, such asincreasing wall insulation values to

Table 1

Prescriptive Standards

Thermal Envelope R-value Requirements

Above- Below- Slab FloorRegion Heating Ceiling Grade Floor Grade Base- On Window Door*

Fuel Wall Wall ment Grade

Region 1

Southeast All Fuels R-38 R-21 R-30 R-15 R-10 R-15 R-3 R-2.5, 7

Region 2G Natural

Southcentral Gas R-38 R-18 R-19 R-10 R-10 R-10 R-3 R-2.5, 7

Region 2A All

Southcentral, Fuels R-38 R-25 R-30 R-15 R-10 R-15 R-3 R-2.5, 7

Aleutian Other Than

Kodiak Natural Gas

Region 3

Interior & All Fuels R-38 R-25 R-38 R-19 R-10 R-15 R-3 R-7

Southwest

Region 4

Northwest All Fuels R-38 R-30 R-38 R-19 R-10 R-15 R-3 R-7

Region 5

Arctic Slope All Fuels R-52 R-35 R-43 N/A N/A N/A R-3 R-7

* Not more than one exterior door in a residential building in Region 1 or 2 may have an R-value less than 7but not less than 2.5.

2


16/8217

make up for north-facing windows.You are not allowed to trade offinsulation values with differentthermal envelope assemblies. Inother words, you could not use thiscompliance method to reach a heatloss target by increasing the R-value of the roof insulation to makeup for low wall or floor insulationvalues. Therefore you cannot usethe performance method to makeup for the lack of R-value in a logwall.

4. Energy Rated Method

The energy rated method requiresthat the building shall achieve at

least four-star plus (83 points) onan energy rating performed by atrained and certified energy rater.This is the method most often usedby builders to comply with BEES.An energy rater records the R-valuesof all the elements of the thermalenvelope and notes the efficiency ofthe heating appliances, lighting,solar aspect, and other energy useconsiderations.

The most crucial aspect of theenergy rating for the log builder isthe blower door test, which uses apowerful fan to depressurize your

Using a blower door to test the airtight-ness of a log home in Arctic Village.

photo

byPhilLoudon

house and accurately measure theair loss from leakage. This test alsohelps a builder find those leaks.Several tight log homes have quali-fied for a four-star plus energyrating, and a few log homes havemade a five-star rating, scoring 88points on an energy rating. A newlog home in Fairbanks was recentlyrated five-star plus.


17/8219

Chapter 4Building the Log House

In the Woods

Trees are a renewable resource iflogged on a sustainable timeschedule of a hundred or moreyears between harvests. The way toensure a perpetual source of houselogs is selective logging.

House logs are best cut inwinter, when the sap is down andthe logs can be skidded over the

snow with minimum damage to thelogs and the environment. Barkbeetles are dormant in winter, and along winter drying season may drythe logs enough to keep the beetlepopulation down in the spring.Bark beetles will not invade drylogs.

Choose trees that are of thelength and diameter that will suityour needs. Think in terms of

cutting a matched set of logs withthe same mid-point diameter.

Leave the remaining trees un-damaged by traveling lightly on theland as you skid the logs out of theforest. The trees left behind willbenefit from having more light andspace to grow in.

A modern equivalent to horse-logging is a four wheeler fitted withan arched log-carrying frameequipped with a 2,000-poundcapacity electric winch powered bythe 12-volt battery system of the off-road vehicle (see drawing below).

Saw safety: use hearingprotection and eyeprotection when usinga chain saw. Never cut

with the top part of thetip of the blade. If youdo, the saw could kickback into your face.

An arched log-carrying frame that is pulled bya four-wheeler style all-terrain vehicle.


18/8220

Whether you are clearing yourown land or logging a timber sale,keep waste to a minimum. Maxi-mize the use of local wood productswhenever possible. Birch makesgood cabinet building material andflooring or window and door trim.Aspen and poplar or spruce makegood paneling, wainscoting, andtrim. Douglas fir, hemlock, andwhite spruce can be made intoframing lumber or timbers for postand beam construction.

White spruce trees are likely tobe the logs of choice for building ininterior or southcentral Alaska.Large, straight aspen or whitepoplar can also be used. In southernAlaska, yellow cedar and westernred cedar, Sitka spruce, Douglas fir,and western hemlock all are excel-lent log building materials if theyare straight and of the size requiredfor your building. Alaska yellowcedar is very strong and verydurable and suitable for cabinetryand furniture, power poles andpilings, decking, bridges, andhousing.

Dont peel too far ahead of theactual placement of the logs on thewall, since the bark protects thewood from mechanical damage,mold, and mildew.

Weathering

Logs may have to be treated with adilute solution of mildewcide afterpeeling to keep them from turning

green or black with mold. Somebuilders prefer to use a solution ofborate crystals dissolved in waterand sprayed on the logs to retardmold growth. Borate is less toxic tothe environment and to the logworkers than some other chemicalsused to protect logs from mold.

Sawmill Island

(As told by Robert Charlie, director of the Cultural Heritageand Education Institute.)

Sawmill Island is located directly across from Old Minto, whichis about 30 miles downriver from Nenana. Old Minto was

originally settled in 1912 by a group of Athabascans from theMinto Flats area. Today, Old Minto is the site of a cultural

heritage camp. One of the reasons that Chief Charlie originally

settled in Old Minto in 1912 was the abundance of timber

found at Old Minto and across the river on Sawmill Island.Sawmill Island is about 1.7 miles long. The timber served many

purposes, but it was primarily used for fuel by the community

members and later for contracts with the United Statesgovernment.

In the early 1920s, Robert Charlies uncle, Arthur Wright, whowas one of the first Native ministers for the Episcopal Church

in Alaska, used timbers from Sawmill Island to build Old

Mintos first school. The two-story structure was about 60 by

80 feet. Arthur Wright had a small portable sawmill located onthe island. Also built of timbers from Sawmill Island was the

Episcopal Church that stills stands today. The Cultural Heritageand Education Institute is working to preserve it as a historical

site.

Years ago, there were four or five winter trails to the island

that led to dry timber areas. Everyone in the village used theisland to get wood. Also, you could walk into the woods in

the summer, and pick gallons of cranberries.

During World War II, the federal government was busy building

Galena Air Force Base. About that time, Robert Charlies dad

was the first contractor with the Alaska Railroad (federalgovernment) to sign for cord wood. The first year he signed

for 50 cords of wood, the second year for 100 cords of

wood, and the third year for 150 cords. Most of that woodcame from Sawmill Island.

Later on, Roberts dad signed a contract with the federalgovernment to produce 1,000 cords of wood. People from his

village produced the 1,000 cords of wood. Roberts brothers

and dad cut about 360 cords. People would stack the cords

along the river and the steamboats would use them to power

the boats up and down the Tanana and Yukon rivers. During

the war, the federal government leased steamers from Canada

and had another three steamers that traveled these rivers,hauling materials to the Galena base.

Today, Neil Charlies allotment is partly located on Sawmill

Island. Robert Charlie says that his family used to have their fish

camp on the island. He remembers as a child seeing old slabsof wood and sawdust where Wright had his portable sawmill.


19/8221

wind

Stop felling completelyin high winds.

Use the lean of the tree tostart the fall.

Check the landing area for hiddenstumps or rocks that can damage

your valuable tree. Dont damagethe other trees.

Plan ahead foryour escaperoute (watch thebutt: it kicks).

One-third of the waythrough the tree

First cut a wedge-shapedchunk about one third of the

way through the tree in the

direction you want it to fall.

plastic

fellingwedge Then make thesecond cut on theother side of thetree, slightly abovethe first cut. Use afelling wedge ifneeded to start thetree falling.

Leave wood in the middle for a

hingeso the tree falls in the rightdirection.

Safe tree felling


20/8222

After a couple of years lyingaround with the bark on, logs willstart to rot and may become barkbeetle habitat. At this point, it maybe best to peel the logs and treatthem with a water-repellent woodpreservative to keep them sounduntil you can begin to build.

Spring is the worst time to felland peel a log. However, if youmust use wet, green logs, placethem on the wall as soon as pos-sible so that they take a set in linewith the shape of the building.

If the logs begin to turn greenwith mold, wash them with asolution of household bleach anddetergent, rinse thoroughly, andallow to dry completely. Protectthem with a water-repellent woodpreservative and allow them toseason before applying the finalfinish.

The Foundation

As we noted earlier, the configura-tion of a foundation for a log houseis the same as a good foundation

for any structure of comparablesize and weight. The differencecomes in the weight of the walls,and the means of attaching the firstround of logs to the foundation.

There is an ongoing debate ofwhether to place the first logsdirectly on top of the treated foun-dation sill plate or on top of atimber of the same height as thefloor joists. If you use a timber for arim joist, it is a relatively easymatter to attach the first round oflogs, using whatever pinningsystem you use for the rest of thelog wall. Some log builders prefer tobuild on top of the plywoodsubfloor, which has been framed tothe outside of the sill plate. In eithercase, the logs or timbers must besecurely attached to the foundationwith long anchor bolts or withcoupling nuts connecting all-threadrods to the anchor bolts. Somebuilders extend 1/2-inch rebar 18inches to 2 feet out of the founda-tion, drill the log accordingly, andbend the rebar tightly against thefirst logs with a sledge hammer. Ifthe logs sit on top of a floor, addi-tional blocking should be installedwhere the joists are parallel to thelay of the logs.

Add blocking (crush blocks)under the wall where thelogs run parallel to the floor

joists.

rim joist

pressure-treated ornaturally decay-resistant

wood sill plate, withclosed-cell sill sealerunderneath

floor joistfiberglass

foaminsulation

untreated wood mustbe at least 6 inchesabove ground


21/8223

flashing

6-by-10 timber

closed cell

sill sealer

closed cell sill sealer and caulk

hardwood dowels,

steel pins, rebar or bolts

protection board

or coating required

damp proofing

exterior

foam insulation

R-value varies

with region

and design

seal all cracks, penetrations, and

joints with approved sealer

4-inch concrete slab

radon/moisture retarderrigid foam insulation

compacted earth

non-frost-susceptible materials

gravel base

heated basement

radon sub-slab suction system

2-inch ledger for floor joists to rest on

rigid foam caulked on four sides with Tremco

countersink

Sheetrock

vapor retarder

R-value varies with region

and design

treated lumber or naturally

decay-resistant wood sill plate


22/8224

NOME

ANCHORAGE

FAIRBANKS

BETHEL

2

3

4

2Possible Magnitude

max. damage (Richter) of largest

Zone to structures earthquake

0 none less than 3.0

1 minor 3.04.5

2 moderate 4.56.0

3 major greater than 6.0

potential damage is greater than

4 zone 3 due to geologic and tectonic

features

Source: Environmental Atlas of Alaska, 1978

Charles Hartman and Philip Johnson

3

Rebar set in the concrete and leftprotruding high enough to come

through the first round and then bentover parallel with the log. This methodwill also work with a standard rim joistand crush blocks (see illustration onpage 22).

Plan ahead and decideon the method ofanchoring before youpour concreteor install piers.

Options for attaching the half log to the foundation

Seismic zones in Alaska

A long J-bolt anchor lefthigh enough for a largetimber to be bolteddown and woodendowels or rebar used toanchor the logs to thistimber.

countersink 1"


23/8225

Most of the engineered ply-wood I-beam systems have compat-ible laminated rim joists, whichmay eliminate the need for extracrush blocking along the ends ofthe joists. Follow manufacturersdirections. In any case, build itstrong so that the connections ofthe logs to the foundation, theconnections between logs, and theconnection of the roof to the logsare all designed to meet the engi-neering requirements of yourspecific earthquake zone, windload, and snow load design levels(see seismic zones map, previouspage).

Permafrost Foundations

One way to support a log structureon permafrost is to build it onpilings that are drilled, driven, ordug to below the active seasonalfrost layer and deep enough toprovide lateral sway bracing. Itshould be drilled deep enough intothe permanently frozen ground tofreeze the piling in place. The floor

must be well insulated and situated

wood beam

3'-0"wedges

U-bolts

three layers of

pressure-treated

lumber

wood beam

plywood plate

8 inches

active freeze-thaw layer(at least 40 inches;may be much more)

12 inches dia.

timber piling

sand slurry

polyethylene orasphalt paperwrapped aroundpiling

Examples of foundationsfor permafrost


24/8226

about three feet above grade toallow outside air to flow under thehouse in winter to keep the groundfrozen and to shade the surface insummer from the heat of the sun.Avoid disturbing the organicground cover that insulates the soil.(See Building in the Northby Eb Ricefor an in-depth discussion. SeeAppendix D.)

Another permafrost foundationis post and pad, where a bed ofgravel is placed on the undisturbedvegetation mat and treated woodtimbers are embedded in the graveland tightly stacked in alternatinglayers to support either posts orbeams to support the building.Some builders are building a treatedtimber system of railroad ties andhorizontal beams to support a homeon a gravel pad.

A promising new-high techpermafrost foundation calledTriodetic has been used extensivelyin the Canadian north and has beenused in arctic Alaska in the last fewyears with apparent success. TheTriodetic foundation system incor-porates a series of interconnectedtriangles of steel tubes to form abridge over unstable soils.

The Triodetic brand space frame is one option for building onpermafrost.

A nice-looking post and pad foundation installed near Fairbanks.


25/8227

Log Working Tools

A log builders tool kit can range incost and complexity from an ax anda cross-cut saw to an array of chainsaws, electric planers, routers,grinders, and drills. The main tool

in a modern log workers kit is apowerful, lightweight chain sawwith a 16-to-20-inch bar. Rubberanti-vibration dampers shouldconnect the handlebar to the saw toprotect the operator from problemswith his or her hands.

Other essential tools include agood sharp ax; a draw knife; asharp pocket knife; a log scribefitted with level bubbles; pencils,

marking pens, and lumber crayons;a chalk-box string line; a two-footcarpenters level; heavy-dutyelectric drill and auger bits; chisels;wooden mallet; claw hammer; andsledge hammers. For moving logsyou will need Peaveys and a me-chanical winch or a block andtackle system. For big logs you willneed a crane or a high lift system ofsome sort. For sources of log work-ing tools, see Appendix D, page D-8.

cant hook

Peavey

Swede hook(log carrier)

chalk box/plumb bob

slickcurvedgouge

chisel

log dogs (24 to 36inches long, 4 to 6inches high)

log scribe

2-pound

sledge

drawknife

axe

chain saw guidescorp

gouge knifeor scorp

electric chain saw sharpener

adz


26/8228

Half Logs

The first round begins with a pairof half logs. These are usually runthe shortest length of the building.When supported at each end, eitheron the wall or on a pair of skids, a

log will usually come to rest withthe bow down and the straightedges to the sides. Roll the log backand forth with a Peavey to locatethe very straightest lie and hold itin place with a log dog or withwedges with the straight edges ofthe log to the sides (see illustration#1, next page).

Use a chalk line to snap a linedown the center of the mass of the

log. Use a level to mark verticallines on each end of the log at thecenterline just established (see #2,next page).

Then roll the log over until theend marks are horizontal. Dogsecurely and snap a line down thelength of the log on the other side.

If you have an attachment toturn your chain saw into a two-man saw, then sawing the half logsis relatively straightforward sinceeach of you have a line to guide thesaw. If you are cutting singlehandedly, you may want to placean observer on the far side to signalup or down.

If you cut the half log from avertical position, with the log lyingwith the centerline on top, it is bestto have only one sawyer cut theentire length of the log from oneend to the next without changingdirection. That way, if one personssense of vertical is a little bit out, atleast it will be consistent and wontcompound any error.

Once the log is sawn in half,secure both halves in a horizontalposition and brush the surfacestraight and smooth with the edgeof your chain saw. This is an ac-quired skill and will come with alittle practice.

Snap a center line on the bottomof both half logs and snap anotherparallel line near the outer edge justoutside the foundation (see #4, nextpage). Cut a 1/4-inch-deep kerf at theouter line with a circular saw tohold a metal drip edge flashing. Ifyou do not have metal flashingavailable, cut a 1/4-inch deep groovewith a chain saw to serve as a dripbreak and to prevent water fromflowing under the first round oflogs.

Transfer the center line to thetop of each half log, using a level toextend a line on each end of the log.The half logs are then placed on thefoundation with the center markslined up with the wall centerlinesmarked on the foundation or floor.Place any bow to the outside. Buttends should run the same directionso that when you reach the top ofthe wall, the top round will end upwith the butts facing the same wayto support a long roof overhang atthe gable ends if desired, and thetop round will be easier to finish inany case. Some builders choose toalternate the butt-tip lie of the halflogs and subsequent plate logs.

Use closed-cell sill seal or EPDM

gaskets to provide a weather-tightseal between the half logs and thefloor or foundation. Caulk the firstlogs to the floor with a bead ofsealant along each side of the sillseal.


27/8229

Cutting the half log

3

4

2

1wooden wedge tohold log in place

log dog

cutting the kerf for flashing

or cut saddle on topof support logs


28/8230

;y;y

;y

;

;

y

y

CL

CL

First round half logs are usually runthe shortest length of the building.

pair small ends inthe same direction

Line up centerlineof logs with layoutlines on floor.

first round half logs withflashing groove already cut

three-quarter logs

flashinggroove or kerf

flashing

sill sealer

sill sealer

sideA side

B

sideA

sideB

Line up the logs overthe foundation.

bead of sealant (caulk)


29/8231

Three-quarter Logs

The second logs to be placed areoften referred to as three-quarterlogs because about a quarter of thelog is cut off the bottom to restsquarely on the foundation or floor.

Slab off the bottom of the three-quarter logs to provide a flat widthof about six inches, using the sametechniques described for cutting thehalf log. The width of the flatbottom of the three-quarter logsmay vary from end to end in orderto leave enough wood over thenotches. Always consider theheight of the log to be crossed andthe diameter of the butt or tip that

will be crossing over the log youare working on.

Cut a 1/4-inch deep kerf forflashing parallel to the centerline ofthe log just outside the foundationor floor line. Place the two three-quarter logs on top of and at rightangles to the half logs, with thecenterlines lining up with thecenterlines marked on the floor orfoundation.

Check to be sure that the flatbottoms are exactly parallel to thefloor and shim them to level ifrequired so that when notched to fitover the half logs, they will lay flaton the floor, evenly compressingthe closed-cell seal sill gasketmaterial under the bottom round.

There are several ways to notchthis first round together. This and ahost of other notches are discussedin detail by B. Allan Mackie inBuilding With Logs and Notches ofAll Kinds (see bibliography inAppendix D for these and otherbooks). All notches should be self-draining and should restrict theflow of heat, air, and moisture inand out of the structure for the lifeof the building.

Compression-FitSaddle Notch

The current notch of choice byprofessional log builders is thecompression-fit saddle notch. Theshoulders of the log below aresaddle-scarfed off at an angle thatforms, in cross section, the shape ofa domed pyramid with the sidessloping toward the top, leavingabout a 3-inch domed top. The top

A good modern log home built with a compression-fit saddlenotch.

Prebuilding the log walls at a convenient place before reassem-bling at the final homesite. The logs are peeled just before use tokeep them in good shape.


30/8232

should be about the same width asthe lateral groove of the next log.

By cutting the scarfs (see page34) you remove the sapwood,which tends to shrink and com-press more than the heartwooddoes. You also create a betterlocking shape so that the top logfits over the log below like a hugepipe wrench, preventing it fromtwisting or turning. You have to cuta relief opening in the top of thenotch so that the sides of the notchcan bear the weight of the logs asthey shrink and settle.

The compression-fit notchcomes to us from Scandinavia viaCanada thanks to the reinventionof an ancient Norwegian logbuilding technique by DelRadomske, a Canadian log homebuilder, inventor, teacher, andauthor. Radomske noticed that hisonce-perfectly fit full-scribed roundnotches were opening up after afew years of shrinking and settling.After perfecting the saddle notch,he observed that if there should be75 percent of the weight of a logresting on the notch and the re-maining 25 percent of the weighton the long or lateral groove, then

it would make sense to overscribethe lateral groove so that as the logssettled and shrunk, the lateralgroove would not hang up and holdthe notch open. He experimentedwith first a 1/8-inch overscribe, then1/4-inch, and evolved into an aver-age of 3/8-inch larger scribe settingfor the lateral groove than for thenotch. Over-scribing works bestwhen combined with a saddlenotch. The compression-fit notch,sometimes called shrink-to-fit, isdesigned to get tighter as the logssettle and shrink. Radomske is stillexperimenting with this shrink-to-fit system, as are numerous otherlog builders who search for perfec-tion.

Round Notch

The round notch full-scribe tech-nique typically uses identical scribesettings for both the long grooveand the round notches. It wouldprobably be better to overscribe around notch building, but the logshould bear on the top of the notch

and not on the sides. The roundnotch will not keep the log belowfrom twisting. To tie the logs to-gether, drive hardwood pegs,dowels, through-bolts, or lag bolts,or pin them with rebar into pre-drilled holes through each round oflogs to the rounds below. Keep trackof the pins with marks on the logsso that you dont hit them whencutting out a window or spline.

Log Scriber

A modern log scriber consists of a10 or 12-inch divider fitted with apencil holder and adjustable levelbubbles. The principle of scribing isbased on parallel lines. The bottomleg of the scriber rides along the

A compression fitsaddle notch


31/8233

Using a layout board to mark the log for a scarf. See drawing #3,page 37.

Use a benchmark to set the levelbubbles for consistency.

lower log and the upper leg tracesits shape on the upper log. Thelevel bubbles are adjusted to main-tain horizontal and vertical controlof the dividers so that the exactshape of the lower log, includingbumps or depressions, is trans-ferred to the upper log. Many logbuilders use indelible pencils, andsome spray the logs with water orwindow washing solution from amist bottle to darken the line. Somebuilders adapt the pencil holder toaccept Sharpie-style felt-tip pins.This type of marker is especiallyuseful if you are scribing icy logs.

The First Scribe

The first scribing you will do is tofit the three-quarter logs to the halflogs. If you choose to use thesaddle-notch technique, you mayfirst cut scarfs on the shoulders ofthe half log. Some log buildersround notch the half and three-quarter logs. The shape of the scarfis often marked on the log, using atemplate to lay out scarf dimen-

sions to ensure consistency ofappearance.

The scarf cut is made with achain saw, using a sweeping mo-tion somewhat similar to using aparing knife to remove a smallbruise on an apple. The slopedplane of the scarf must be consis-tent to provide a uniform bearingsurface for the sides of the notch inthe log above. Sand or plane the

face of the scarf smooth.For the first round, the notches

should be under-scribed about ahalf inch so that with shrinkageand settlement the flat bottom ofthe three-quarter log will not hangup on the floor and cause thenotches to open. This first roundwill require a wide scribe setting,


32/8234

cutting the scarf

brushing with the chainsaw to smooth thescarf

and considerable care must be takento ensure that the level bubbles areset exactly so that the points of thescribe are perpendicular to the floor.This setting can be verified bychecking against a plumb linemarked on a perfectly verticalsurface previously established nearthe building site.

Scribing the Notch

The log to be notched is placed sothat the center line of its mass isexactly over the wall center linemarked on the subfloor or founda-tion, with the straightest sidesparallel to the floor. With the

straightest sides top and bottomand any bow to the outside of thebuilding, dog the log firmly in placeso that it will not budge with peoplesitting or walking on it.

With the exception of the firstround, which is flattened on the


33/8235

Scarf is sanded smooth, ready for final scribing. Notestress relief kerf on top of logs to promote controlled

checking.

Scribing for the groove

Hold the scribe gently with both hands,keeping the level bubbles between thelines.

bottom and therefore has a predict-able depth of notch, all other logsmust be rough notched or firstnotched to drop the new log towithin 1 1/2or 2 inches of the logbelow. This is easily done by open-ing the scribe to the space betweenthe logs just inside the notch ateach end. Mark this setting on the

top of the log and reduce the scribesetting by the distance you wish touse for your final scribe, say 2inches or three fingers width. Scribethe first notch with this new setting.

Hold the scribe gently with bothhands, and keeping the levelbubbles between the lines, scribe


34/8236

from the bottom up and the topdown on both sides of the lowerlog. Move to the other side of thenew log and scribe with the samesetting.

Move to the other end, open thescribe to the space between the logsand close the dividers down by thesame amount as the other firstnotch. Repeat the same procedurefor the other notch.

When you cut the roughnotches and roll the log back inplace, the log should be parallel toand 1 1/2to 2 inches above thelower log. Place the center of thelog exactly over the center of thewall below. Mark on top of thelower log with an indelible penciland a plumbed 2-foot level theexact location where the new logcrosses the lower log for futurereference.

Final Scribing

Stand back and evaluate the gen-eral lay of the log to be finalscribed. Note the largest gap and

shim the log if necessary to main-tain a consistent lateral notch widthof about three or four inches.

Set the scribers to the largestgap between the two logs, thenopen them up about 1/8inch andfinal scribe the two notches at thissetting.Remember, you will open thefinal scribed setting at least 3/8inch toover-scribe the lateral notch.

Overscribe the log end exten-

sions another 1/4inch to preventthem from hanging up, since theinterior of the log walls are gener-ally heated and will dry out morerapidly than the unheated log ends.

Back on the Ground

Once the log being worked on hasbeen scribed all the way along bothsides, up and over the logs at eachintersecting wall, and around bothends with a continuous line outlin-

ing the shape of the logs below, thenthe log dogs can be removed andthe log boomed down off the walland placed on log cribbing of acomfortable height to do all thechain saw work with both feet onthe ground.

We have found it faster andsafer to do most of the chain sawingstanding on the ground. If youdont have a crane to easily move

the logs, which is often the case forowner builders, you can do all thechain saw work up on the wall. Thisis dangerous work, on or off theground. Totally concentrate on thetask at hand, yet be aware of what isgoing on around you. Practicesafety at all times. Always wear eyeand hearing protection.

Do not get between a movinglog and a hard place. When undo-ing a log dog, have someone holdthe opposite end of the log with aPeavey with both of you standing tothe inside of the house and no onebelow you on the ground. Some-times a very crooked log can rollwith a lot of force and throw a logworker off the wall. Work in pairsand look after each other.

Cutting the Notch

If you are using a chain saw to cutthe notch and you are working withdry logs, it is a good idea to scorealong the scribe line with a sharpknife to prevent splinters fromextending beyond the scribe line.You could also use a sharp ax heldin one hand and a mallet to tap the


35/8237

5

1

3

2

4

6

A rough or first scribeRemove the wood in pieces and roll the log over.

Use a layout board to keep all the scarfs thesame.

The final scribe

Most of the wood is cut with a chainsaw, but cutthe last quarter inch with hand tools.

The notch should be smooth and slightlycupped to accommodate insulation and preventhanging up on the lower log.


36/8238

A

A

B

B

C

C

overscribe about 3/8-inch

overscribe 5/8-inch

5/8inch

The final scribe is visible on this log on the skids, ready for cutting.

head of the ax as if it were a largechisel to score the line.

Cut from one side of the log at atime so that you can see when youare getting close to the scribe line.Leave about a quarter of an inch ofwood between your saw and theline so that you dont turn anexpensive log into firewood bycutting beyond the scribe line. Cutthe remaining wood with a sharpaxe, chisel, or a sharp pocket knife.

For a small notch you may onlyneed to cut one vertical slice downthe center of the notch and oneangled cut along each side of thenotch.

Repeat the three cuts from theother side of the notch, and knockout the chunks of wood with theback of your ax or with a hammer.A larger notch may require a fewmore slices. With practice, anexperienced log worker can removemost of the wood within the scribeline in only a few large chunks.

Brush the remaining wood to beremoved from the notch with thebottom quarter of the nose of thesaw bar. Clean up the sides and thebottom by sweeping sideways backand forth with the bottom sector ofthe tip of the bar. Work from the topdown and from the center of the logto just short of the scribe line.

When youre done, the notchshould be smooth and slightlycupped to accommodate insulationand prevent hanging up on the

lower log. The sides of a compres-sion-fit notch must have strongedges to carry the weight of the logwhen the lateral notch is over-scribed (see Appendix B, page B-13,Log Building Standards).


37/8239

Site-made log holders keep logs aligned at a precut door orwindow during scribing.

A lock notch is used when a log tip is too small to be notchedwithout weakening it considerably. A lock notch can also be usedon the plate log at the top of a wall for added strength to keepthe walls from splaying outward.

bottom log

top log(upside down)

Cutting the LateralGroove

The long Vgroove is no longerin favor since it removes morewood than necessary and in somecases weakens the logs to the pointwhere they slump on the wall andopen up the notches, which are nolonger carrying the weight. A moreperfect groove is the continuouscope, which is tedious with a chainsaw but can be done with a gouge-type adz or with a specialized toolcalled the Mackie gouge knife, alsoknown as a scorp.

TheWcut groove is mostfrequently used now by log build-ing professionals. This cut removesmuch less wood than the Vgroove.Instead of making two deep cuts tocreate a V, you make four shallowcuts to form a W(see next page). Anarrow groove is tighter andstronger and faster to cut than awide groove.

Begin by cutting just inside thescribe line with the saw aimed just

above the center or radius point ofthe log. Make the first cut about aninch or two inches deep, dependingon the size of the log and the shapeof the log below.

The second cut is a repeat of thefirst cut from the other side of thegroove. The third cut is a linestarting at the top of the first cutand connecting at the bottom of thesecond cut. The fourth cut removes

the wood remaining near the firstcut, and a Wwill be formed incross-section.

You may have to remove someof the center portion of the Wif atrial fit with a short piece of logsimilar to the log below hangs upand will prevent the log beingworked on from settling properly. Ifnecessary, the center of the Wis

Plumb centerline markedon log ends

with level


38/8240

A W-groove in a log. Note shims tokeep the clearance for the overscribe.

continuous cope groove

1 234

Wgroove

Mackie gouge knife

traditional scorp

A sequence for cutting the Wgroove

Cutting the groove with a chainsaw.


39/8241

slip joint for log settling

3/4-by-6-inch tongue and groove

perpendicular to purlin. Caulk

between boards at the plate log.

continuous vapor retarder

rigid foam between 2-by-4 nailers

chinking on exterior for

high wind areas

sealant or gasket

insulate

plate log

purlin

half log floor

closed-cellsill seal

gasket or sealant

vapor retarder on warm sideTyvek on

cold side

easily removed with a long-handledcurved gouge or with a scorp asdescribed earlier.

The Log Walls

Carefully align the center of

mass of succeeding logs as they arepositioned for scribing. Since youare working with a natural mate-rial, some of the logs will becurved. The overall objective is tohave the average center of all thelogs bear down on the center line ofthe wall, which in turn bears on thecenterline of the foundation.

Considerable time should betaken rolling and sliding the log

with a Peavey to be sure the log iswell centered and the straightestsides are top and bottom with anycurve to the outside of the building.Station a log worker at each end ofthe log to be aligned with Peaveysin hand. Each person should eye-ball the log and make small adjust-ments until both ends are wellcentered. Stand back from the wallseveral feet and hang a plumb bob

as a sight line to examine the lay ofthe log. Do this from each end tosatisfy yourself that the wall isgoing up straight and plumb. Dogthe log securely and scribe andnotch as described above.

As the walls get higher, youneed to keep a check on the heightof all the walls and keep the even-numbered rounds about the sameheight. Carefully select logs that are

of the correct diameter to maintainequal log wall heights. Strive at alltimes to cut about halfway throughthe log with the corner notches.This is of course the ideal and canonly happen if the logs were turnedon a lathe to exactly the samediameter.

If a small tip must notch over alarge butt, a lock notch should beused to leave enough wood to avoidbreaking the tip (see illustration,page 39). See Log Building Construc-tion Guideby Rob Chambers for adetailed discussion of log selection(see Appendix D, References andBibliography).


40/8242

Sealing the vapor barrier around a log ridge pole.

Both fiberglass and backer rod installed on a log.

Airtight Log Walls

The log walls must be airtight toresist the flows of heat, air, andmoisture. This can be accomplishedwith the use of tar-saturated foamstrips such as EM Seal, EPDM

gaskets, or backer rod and flexiblechinking materials such asPermachink or equivalent, andtight-fitting log work. Seal the

cracks between logs on or near theinside surface to prevent moisture-laden air from reaching the dewpoint and condensing between logs,causing accelerated self-destruction.Properly fitted, full-scribe logs willnot require any visible chinkingsuch as was used in the old days tokeep out the weather and keep thecat inside. In high wind and rainenvironments you should air-sealboth inside and outside the logs.

Finishing the Logs

On the inside, two coats of log oil orclear acrylic latex or polyurethanevarnish should be enough of a

vapor retarder to slow the flow ofhousehold water vapor through thelogs. You will want to treat theoutside of the logs with a UV-inhibiting water repellent preserva-tive log oil or stain. Clear exteriorfinishes do not last as long orprotect the logs as well as pig-mented finishes. There are manyproducts on the market designed to

Logs ready to be lifted into place.


41/8243

airborne fiberglass

particles

air leak

indoorsoutdoors

indoorsoutdoors

poor seal

better seal

backer rod

or gasket

Fiberglass sealing of log walls: good and bad

caulking

chinking

backer rodor gasket

fair seal

outdoors indoors

outdoors indoors

best seal

both sides

finish logs, so do your homeworkto see what is recommended in theliterature and by the variousvendors or in the trade journals.

Chinking and Sealing

Fiberglass chinking or fiberglasssill seal alone will not createenough of an air seal to pass ablower door test. Unless the logwork is very tight and will remainairtight over time, it is not likely topass the airtightness requirementsof BEES.

A closeup of the log in place with fiberglass and gaskets.

Fiberglass chink-

ing or fiberglass

sill seal alone will

not create

enough of an air

seal.

Dualfoambacker rod

Dualfoambacker rod

fiberglass

kerf


42/8244

seal all panel joints

with subfloor adhesive

Chinking withtrapezoidal ortriangular backer

rod (could be doneon inside or bothsides).

outdoors

indoors

Glue joints between pieces of plywood and glue the plywood tothe joists. Ideally, use 3/4 " tongue and groove exterior gradeplywood. Glue, nail, and screw for a squeak-free floor system.

There are several log chinkingmaterials available to make a loghouse tight.

The log building details pre-sented in this book describe how toconstruct scribe-fit chinkless loghomes. However, some people likethe looks of chinking, and manyolder log homes may be in need ofchinking to reduce infiltrationbetween the logs.

Modern chinking systemsrequire the use of triangular ortrapezoidal-shaped backer rod toform an even, flat surface uponwhich to spread the chinkingmaterial. Use a flexible chinkingmaterial such as Perma-Chink orWeatherall over the backer rod for adurable seal between the logs.

Old-time chinking materialssuch as sphagnum moss or oakumare rarely used in todays loghomes. Clean sphagnum moss is agood alternative insulation for logbuilding in the bush but may not bein the AkWarm computer files.

Short Log Construction

If you do not have any liftingequipment, you can build a goodlog house using logs short enoughto be handled by a couple of people.A traditional method of stacking upshort logs to frame a wall is knownby its French name as pice-sur-pice, or piece-on-piece in English.This is a variation of squared postand beam construction where ahorizontal infill of round logs isfitted between vertical round logposts. The vertical posts are flat-tened on two sides and grooved toaccept a tenon fashioned on each endof the log infill pieces.


43/8245

Piece-sur-piece, orpiece on piece

This large building, rebuilt at the site of old Fort Edmonton,Canada, was built piece-sur-piece.

PhotobyPeggySwartz

An alternative to mortise andtenon joinery is to groove both thepost and the infill log ends toreceive a 2-by-4 spline to join them.This method of construction canuse a wall jig to ensure consistency,allowing for all of the wall compo-nents to be prefabricated off siteeven before the foundation iscompleted. Combining post andbeam and square timber framingtechniques with round logs squaredoff only where two or more beamsconnect can allow you to fabricateprecisely engineered structuraltimber frames or trusses in theshop.

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2-by

-12

foilfo

amore

quiva

lent

2-by

-12

caulk 2-by-12s to lowerlog to prevent waterfrom entering lower

channel

fiberglass

4" wideminimumscribe

plate log header(stationary)

fiberglassfiberglass

fiberglassinfill log(beforesettling)

infill log(settled)

2-by

-12

foilfoam

ore

quiva

lent

2-by

-12

Piece-sur-piece top log settling detail


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The portable hydraulic pump for drivingthe tools.

A hydraulic drill being demonstrated ata log building conference. Note theone-handed operation.

No exhaust fumes is one benefit fromusing hydraulic chain saws indoorsduring winter construction.

Making It Easier

Most timber framing tools and logworking tools can be poweredelectrically or even hydraulically.Cutting out frames and trussesinside in the winter can greatly

extend your building season andgive you a jump on the springbuilding season. You can have thehouse structure ready to install onthe foundation as soon as the flooris completed. However, gasoline-powered chainsaws should not beused when working inside a con-fined area because deadly exhaustfumes could build up inside thebuilding. Hydraulic or electric tools

are safer inside.


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Plate logs, purlins, and ridgepoles are higher stress areas, and the biggest andbest logs should be saved for them.

purlin

ridge pole

plate log

Choose the best logs for critical places such as plate logs, purlins, and ridgepoles.

The Plate Log

The plate log, sometimes called thecap log, is the top wall log uponwhich the roof system rests. Theplate logs and the purlins andridgepole are usually picked out

and set aside at the beginning ofthe job. They are straight and havestraight grain and are usually thebiggest and best, strongest andlongest logs since they usuallyextend five or six feet beyond thegable ends. The plate logs should

be chosen from this select group ofthe finest logs to end up level andthe same height from the floor in allfour corners. The plate logs mayhave to be fitted with lockingnotches to resist outward thrustfrom the roof components. Theplate logs could also be through-bolted at the windows and doorheaders and pegged or pinned onclose centers where there are nowindows.


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More Than Just Logs

Traditional Athabascans used the spruce tree in many ways.One important way was for medicinal purposes. Several parts of

the tree, including the top, the inner bark, needles, and the

sap, were used to treat heart problems, kidney trouble, ulcers,stomach sicknesses, weak blood, colds, sore throat, sores,

burns, and tuberculosis. Shamans used the top of the spruce toget rid of bad spirits. Dust from the spruce cone was prescribed

to dry up runny ears, and the pitch was used as an antiseptic

and to stop bleeding. People used the inner bark for bandages.

Spruce trees provided shelter long before Europeans used

them for log cabins. Athabascans used the outer bark for

roofing and flooring, the boughs for insulation, and of courselogs for building walls and roofs. Spruce logs are also used to

build weirs, fish traps, fish racks, canoes, rafts, and other things.

People still use the outer bark of the spruce tree on fish cutting

tables to keep the fish from slipping off. They also use it as a

dye. Boughs could be made into makeshift snowshoes or serve

as mattresses for people and dogs.

Dead spruce wood was useful for smoke for tanning hides andkeeping away mosquitoes, and made dye for moosehide. Of

course, spruce is a good firewood. Also, the wood could becarved to make utensils, tools, toys, fish traps, and weapons.

The roots became lashing for fish traps and snares and were

woven into baskets and fishnets.

Spruce pitch is a useful glue, antiseptic, chewing gum, water-

proofing, and hair dressing.

The information above comes from Eliza Jones and Denaina Ketuna: Tanaina

Plantlore, compiled by Priscilla Kari, and Upper Tanana Ethnobotanyby PriscillaRussell Kari.

Windows and Doors

Typically, heat loss through wallsaccounts for only about 20 percentof the overall energy use of a build-ing. Air leakage typically accountsfor 30 to 35 percent of heat loss.

Windows and doors need to beinstalled with airtight connectionsto the logs with a spline systemnotched into the ends of the logs,which allows the logs to settlewithout increasing air leakage.

Choose windows and doorscarefully for your new log home. Inorder to score well on an energyrating, you must install windowsand doors with high R-values. The

most energy-efficient windows havesome sort of low emissivity (low-E)coating on multiple panes. Thepanes should be separated withnonconductive spacers. The spacebetween the panes may be filledwith an inert gas such as argon orkrypton to reduce convectioncurrents between the panes andincrease the insulation value of thewindow. This energy-efficientglazing system should be fitted intoan airtight insulated frame. Win-dows should have an R-value of atleast R-3, but R-4 or higher wouldfurther reduce heat loss and im-prove your energy rating.

Doors must be R-7 or better.Handmade doors are often craftedto complement a log home and canbe built with a core of very highR-value rigid foam.

Caution! Door and windowcutouts in a log wall are probablythe most dangerous of all chain sawoperations in a log house. Since thetop of the window or door cutout isover the sawyers head, the likeli-hood of a kickback and seriousinjury to the head and face is veryhigh. If you must cut out window


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or door headers over your head,wear a hard hat and hang on tightto the chain saw.

The safest way to cut out thetop of a door or window opening iswhile it is still on the skids where itwas placed for notching. Measurethe exact location for the windowon the bottom side of the headerlog. This will be at the windowheight plus the rough frame dimen-sions plus the anticipated settle-ment space. This will usually befrom 7 to 10 inches greater than theheight of the factory-built windowframe.

Straight, accurate side cuts canbe made using a chain saw lumbermill attached to vertical 2-by-4s or2-by-6s. If you have more than onewindow of the same size, a jigmade of 2-by material can befabricated and moved from win-dow to window. In any case, thevertical legs of the jig should reston the floor, and it should beaccurately plumbed and tempo-rarily nailed to the log wall to keepit from moving during the cuttingoperation.

Cutting the Splines

Windows and doors should beattached to the log walls using avertical 2-by wood spline notchedinto the log ends on each side of theopening. If a log wall with a dooror large window must hold up ahuge snow load, it would be wise

to use 1/4"x1"x2" steel C-channel forspline material in addition to thewood spline.

These spline notches are oftencut with a chain saw using a tech-nique similar to cutting the longW-notch. Be especially careful asyou approach the top of the win-dow. Chances are that you will hit

the header with the top of the sawbar, resulting in a dangerous kick-back situation. Use a very sharpsaw chain at high RPM to minimizekickback and hold on tight to thechainsaw. A much safer method ofcutting these spline notches is to usea heavy-duty router to cut a splinegroove in the log ends. Nail avertical 1x4 to the log ends to guidethe router.

Door and window installationin a log structure requires uniquedetails to maintain an airtight fit asthe logs shrink and settle. The 4-to-6-inch settlement space over doorsand windows must be insulatedand fitted with an airtight vaporretarder that will remain effectiveover time.

Placement and Planning

Windows and doors in a log homeshould be located with consider-ation for solar aspect, prevailingwinter winds, roof avalanchepotential, and the structural ele-ments of log construction. Face the

majority of windows south fornatural light and passive solar heat.

Open doors in so that you canget out if snow drifts pile up out-side the door. Better yet, orient thehouse so that prevailing winds keepyour front porch clear of snow. Donot put yourself and others inharms way by placing an entrydoor under the eaves of an ava-lanche-prone roof. Metal roofs are

notorious for dumping lots of snowall at once. Locate entry doors in thegable end of the house or under aprotective roof.

Air leakage typi-

cally accounts for

30 to 35 percent

of heat loss.


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Cutting out a window using a jig and

guide blocks bolted on each side tothe chain saw bar at both the tip andback near the motor. The bar must bemodified for this.

You should precut window anddoor headers in the logs while they

are still on the ground and upsidedown for notching.

guide blocks


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Cutting out a window using a chain sawmill or guide that is clamped to the barof the chain saw and follows a board,keeping the cut straight and plumb.

Mark the location of any metalspikes or pins so you can avoidhitting them when cutting out the

windows and doors.


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Window spline

Cutting a slot forthe spline

But much preferred is a wooden splinebecause it wont attract water conden-sation and the damage that comes withit.

If the wall is considerably weakened bythe window or door openings, you

may have to use a steel Cchannel forreinforcing the spline.

insulate with sillsealer

insulate with sillsealer

1

2

3

4


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A cold roof is kept cold by air movingabove the insulation and just under theroofing. This prevents ice damming andalso picks up moisture from the insula-tion and carries it out through the ridge

vent.

The Roof

Once you have built an airtight logwall, you must then follow up withan energy-efficient roof, air sealedwith continuous sheets of 6-milpolyethylene with all penetrations

taped or caulked and the ceilingtightly sealed to the log work.There are many ways to put a roofon your log creation to shelter itfrom the elements. The classic loghouse had a low-pitched roof withgenerous eave and gable end

overhangs. The gables were madeof logs, which supported purlinsand a ridgepole and log rafters or aceiling completely framed withevenly sized poles lying side byside. A modern equivalent uses thesame log gables and purlins andridgepole techniques but replacesthe poles with tongue-and-groovespruce or pine paneling, topped offwith an insulated rafter-framedroof.

cap shingle

continuous ridge vent

over roofing

eave vent

maintain minimum air

space required by

vent manufacturer

air space

foam

insulation

vapor

barrier


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caulking

caulk here in the groove where itpasses over the plate log.

plate log

vapor

barrier foaminsulation

eave vent

tongue andgroove ceilingboards

plate log

roof framing

vaporbarrier

tongue andgroove ceilingboards

Sealing the Ceiling

Any style of roof should have anairtight vapor retarder, and the jointbetween the plate log and theceiling should be caulked. Eachtongue and groove ceiling board

should be caulked in the groovewhere it passes over the plate log.The roof rafters should be deepenough to reach the insulationlevels required by BEES. There aremany different ways to build logtrusses or post and purlin or otherlog roof systems that are beyond thescope of this book. The bibliographyhas many good books on log build-ing and roof framing (Appendix D).

Hot Roof or Cold Roof?

The designer must decide whetherto build a hot (unventilated) or acold (ventilated) roof. This decisionis usually based on the likelihood ofsnow building up on the roofduring the course of the winter. Ifsnow will accumulate, then a coldroof is in order.

Snow buildup insulates the roof,causing snow near the roof surfaceto melt from the heat of the build-ing. This melted snow runs downthe roof and refreezes at the edge,forming ice dams. These damscause water to back up underneaththe shingles or metal roofing.

Liquid water in the roof cavityis a problem. The solution to thisproblem is to provide ventilation in

the attic, so heat from the buildingdoes not melt the snow. Provide aminimum of 2-inch continuous airspace over the insulation andcontinuous screened eave and ridgevents.

If the building is on a site ex-posed to high winds and no snow islikely to accumulate on the roof, an

solidblock-

ing

continuous bead ofcaulk on top ofplate log

airspace


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A hot roof must be tightly sealed.

The Roadhouse, 1926

The Alaskan roadhouse is a unique institution, and turns ableak, formidable country into one of hospitality. Nestled in a

clearing in the spired spruce forest, built entirely of rough logs

neatly notched together at the ends, the road house presents acozy and picturesque appearance. The building is divided into a

kitchen and a bunk room by means of a frail partition. In thecenter of the bunk room is a huge cast-iron stove capable of

taking a four-foot green log, which burns all night. Above the

stove is suspended a large rack on which the weary traveler

hangs his damp shoes and clothes, that he may put on dryapparel in the morning. Everything is very comfortable and cozy.

In one corner is a small space partitioned off for an occasional

woman traveler. The beds are two-storied bunks made of stripsof raw moose or caribou hide, called babish,laced across the

bottom. The bed is entirely without linen, but the blanket and

quilts are ample. The floor is spread with shavings, and Cleanli-ness varies according to the owner, but as a rule, each takes

pride in his place and keeps it fairly neat.

fromAlaska Bird Trai lsby Herbert Brandt

Hot roof withno vents ateaves, gables,

or ridge

continuous6-mil. poly

vapor retarder

caulking

airtight hot roof may be desirable.A number of snow-resistant venti-lated roof designs have been ex-perimented with over the yearswith varying degrees of success.Whatever design you choose, keepin mind that an attic full of snowwill not last long. A hot roof mustbe tightly sealed.

All roofs must be designed toaccommodate snow loads and besecurely anchored to resist windand seismic loads.

continuous vapor retardersealed at all penetrations

solid blocking facia

subfacia

rigid foam


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Chapter 5Mechanical Systems

penetrations through the ceilingand roof. All chimneys and plumb-ing vents that pass through the roofsystem must be designed to accom-modate settlement. Flashing andcounter flashing and step flashingaround chimneys should be extratall. Two tight-fitting rubber flash-ings or EPDM flashings should beinstalled over every plumbing vent.The first rubber flashing should be

sealed to the polyethylene vaporretarder where the pipe passesthrough the ceiling, and the secondflashing should be sealed to theroofing material.

Do not allow any connectionbetween a masonry fireplace andlogs. Take care when designing thelayout of the roof system to avoidhitting the ridgepole or purlins andfloor support beams with the

chimney. Ideally, chimney runs arestraight and short.

at leastthree timesdiameter ofsingle wallpipe

plumbing vent

rubber flashing sealedto roof

rubber flashing sealed tovapor retarder

insulatedchimney

caulk

caulk

caulkSee page 82 and Appen-dix B, page B-28 for morechimney details.

Mechanical, electrical, andplumbing systems mustcomply with all applicable nationaland local codes and regulations.Use low-flow shower and sinkfaucets and water-conservingtoilets and install energy-efficientlighting and heating and balancedheat recovery ventilation. In mostof Alaska you have to contend withbelow-freezing weather. Keep wet

pipes out of the outside walls. Allwater entering and leaving thebuilding must be kept from freez-ing and have a safe method ofthawing if it does freeze.

Chimneys and Vents

Any properly sized conventionalheating system will heat a loghome. However, a few precautions

must be taken to maintain anairtight and watertight seal around

drip adapter


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Combustion Air

Fireplaces and wood stoves shouldhave outside combustion air ducteddirectly to the fire box. Furnacesand boilers must be provided withcombustion air per code and

manufacturers instructions. Keepin mind that in an airtight structure,you have to provide combustion airequal to the amount of air passingthrough the heating system and outthe chimney. Combustion air shouldnot be confused with make-up air.Combustion air is designed tosupply only the air required by thefurnace or stove. It should notprovide make-up air for exhaust-

only ventilation systems such asbath fans or a range hood or aclothes dryer. These exhaust appli-ances require their own source of airindependent of the heating equip-ment. Dont let your wood stove orfireplace become the source ofmake-up air for exhaust appliances.This may result in backdrafting theproducts of combustion into the

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crawlspace

opencrawlspace

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Direct to stove with sealedconnection (many new stovesare built to accept this way ofproviding combustion air).

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An option for providing combustionair when the crawlspace or basement

is heated. A cold airp-trap

in pipe

stops cold air from siphoning intohouse when it is not needed.

vent in floor

Maintain a minimum 2 inchesclearance between an insulatedchimney and combustible materi-als. Single-wall chimneys should beat least three times their diameteraway from unprotected combus-tible materials. Be aware of thepossibility of snow sliding on ametal roof and taking the chimneywith it or bending it flat against theroof. This could result in a buildupof deadly gases inside the home.Place the chimney near the peak ofthe roof or protect it with snowstops.


56

Documents

Alaska Log Building Constrution Guide.pdf