STAIR DESIGN 9.03

The dimensions of risers and treads in a stairway should be proportioned to accommodate our body movement. Their pitch, if steep, can make ascent physically tiring as well as psychologically forbidding, and can make descent precarious. If the pitch of a stairway is shallow, its treads should be deep enough to fit our stride.

Building codes regulate the minimum and maximum dimensions of risers and treads; see 9.04–9.05. For comfort, the riser and tread dimensions can be proportioned according to either of the following formulas:• Tread(inches)+2xriser(inches)=24to25• Riser(inches)xtread(inches)=72to75

Exterior stairs are generally not as steep as interior stairs, especially where dangerous conditions such as snow and ice exist. The proportioning formula can therefore be adjusted to yield a sum of26.

For safety, all risers in a flight of stairs should be the same rise and all treads should have the same run. Building codes limit the allowable variation in riser height or tread run to 3/8"(9.5mm).Consult the building code to verify the dimensional guidelines outlined on this and the following page.

• Theactualriserandtreaddimensionsforasetofstairsaredetermined by dividing the total rise or floor-to-floor height by the desired riser height. The result is rounded off to arrive at a whole number of risers. The total rise is then redivided by this whole number to arrive at the actual riser height.

• Thisriserheightmustbecheckedagainstthemaximumriserheight allowed by the building code. If necessary, the number of risers can be increased by one and the actual riser height recalculated.

• Oncetheactualriserheightisfixed,thetreadruncanbedetermined by using the riser:tread proportioning formula.

• Sinceinanyflightofstairs,thereisalwaysonelesstreadthanthe number of risers, the total number of treads and the total run can be easily determined.

Ladders• R=12"(395)o.c.typical

Step Ladders• 12-3/4"(325)riser; 3"(75)tread

• Forprivatestairsonly:• 7-3/4"(195)maximumriser; 10"(255)minimumtread

• 7"(180)maximumriser; 11"(280)minimumtread

• 4"(100)minimumriser

• 1:8maximum

• 1:12maximumwhenpartofanaccessibleroute or an emergency egress system

• Maximumriserheight;minimumtreaddepth for accessible stairs and emergency egress

Stairs

Ramps

Riser and Tread Dimensions Riser Tread inches (mm) inches (mm)

5(125) 15(380) 5-1/4 (135) 14-1/2(370) 5-1/2(140) 14(355) 5-3/4(145) 13-1/2(340) 6(150) 13(330) 6-1/4(160) 12-1/2(320) 6-1/2(165) 12(305) 6-3/4(170) 11-1/2(290) 7(180) 11(280) 7-1/4(185) 10-1/2(265) 7-1/2(190) 10(255)

9.04 STAIR REQUIREMENTS

Stairway design is strictly regulated by the building code, especially when a stairway is an essential part of an emergency egress system. Because an accessible stairway should also serve as a means of egress during an emergency, the ADA accessibility requirements illustrated on the next page are similar to those of an emergency egress stairway.

Stairway Width• Theoccupantload,whichisbasedontheusegroupandthefloor

area served, determines the required width of an exit stairway. Consult the building code for details.

• 44"(1120)minimumwidth;36"(915)minimumforstairwaysserving an occupant load of 49 or less.

• Handrailsmayprojectamaximumof4-1/2"(115)intotherequired width; stringers and trim may project a maximum of1-1/2"(38).

Landings• Landingsshouldbeasleastaswideasthestairwaytheyserve

and have a minimum length equal to the stair width, measured in thedirectionoftravel.Landingsservingstraight-runstairsneednotbelongerthan48"(1220).

• Doorshouldswinginthedirectionofegress.Doorswingmustnotreduce the landing to less than one-half of its required width.

• Whenfullyopen,thedoormustnotintrudeintorequiredwidthbymorethan7"(180).

Handrails• Handrailsarerequiredonbothsidesofthestair.Thebuilding

code allows exceptions for stairs in individual dwelling units.

• 34"to38"(865to965)heightabovetheleadingedgeofthestair treads or nosings.

• Handrailsshouldbecontinuouswithoutinterruptionbyanewelpost or other obstruction.

• Handrailsshouldextendatleast12"(305)horizontallybeyondthe top riser of a stair flight and extend at the slope of the stair run for a horizontal distance of at least one tread depth beyond the last riser nosing of the flight. The ends should return smoothly to a wall or walking surface, or continue to the handrail of an adjacent stair flight.

• Seethenextpagefordetailedhandrailrequirements.

Treads, Risers, and Nosings• Aminimumofthreerisersperflightisrecommendedtoprevent

tripping and may be required by the building code.• Seethenextpagefordetailedtread,riser,andnosing

requirements.• See9.03fortreadandriserproportions.

•12'-0"(3660)maximumrisebetweenlandings

•6'-8"(2030)minimumoverheadclearance

Guardrails• Guardrailsarerequiredtoprotecttheopenor

glazed sides of stairways, ramps, porches, and unenclosed floor and roof openings.

• Guardrailsshouldbeatleast42"(1070)high;guardrailsindwellingsmaybe36"(915)high.

• Guardrailsprotectingtheopenorglazedsideofastairwaymay have the same height as the stair handrails.

• A4"(100)spheremustnotbeabletopassthroughanyopeningintherailingfromthefloorupto34"(865);from34"to42"(865to1070),thepatternmayallowasphereupto8"(205)indiametertopass.

• Guardrailsshouldbeabletowithstandaconcentratedloadapplied nonconcurrently to their top rails in both vertical and horizontal directions. Consult the building code for detailed requirements.

STAIR REQUIREMENTS 9.05

Handrails• Handrailsshouldbefreeofsharporabrasive

elements and have a circular cross section with anoutsidediameterof1-1/4"(32)minimumand2"(51)maximum;othershapesareallowable if they provide equivalent graspability and have a maximum cross-sectional dimension of2-1/4"(57).

• 1-1/2"(38)minimumclearancebetweenhandrail and wall

Nosings• 1-1/2"(38)maximumprotrusion• 1/2"(13)maximumradius• Risersshouldbeslopedortheundersidesofthenosingsshouldhavea60°angleminimumfrom the horizontal.

• 36"(915)minimumclearwidthbetweencurbsor guardrails

• Rampsurfaceshouldbestable,firm,andslip-resistant.

• Curbs,guardrails,orwallsarerequiredtoprevent people from slipping off of the ramp; 4"(100)minimumcurborbarrierheight.

Landings• Rampsshouldhavelevellandingsateachendwitha60"(1525)minimumlength.

• Landingshouldbeaswideasthewidestrampleading to it.

• 60"x60"(1525x1525)minimumlandingwhere ramp changes direction

Handrails• Rampshavingarisegreaterthan6"(150orarungreaterthan72"(1830)shouldhavehandrails along both sides.

• Handrailrequirementsarethesameasforstairways.

• Extendhandrailsatleast12"(305)horizontally beyond the top and bottom of ramp runs.

ADA Accessibility GuidelinesAccessible stairs should also serve as a means of egress during an emergency, or lead to an accessible area of refuge where people who are unable to use stairs may remain temporarily in safety to await assistance during an emergency evacuation.

Risers and Treads• Treaddepth:11"(280)minimum• Riserheight:4"(100)minimum;7"(180)maximum• Uniformriserandtreaddimensionsarerequired.• Openrisersarenotpermitted.

RampsRampsprovidesmoothtransitionsbetweenthefloorlevels of a building. To have comfortable low slopes, they require relatively long runs. They are typically used to accommodate a change in level along an accessible route or to provide access for wheeled equipment. Short, straight ramps act as beams and may be constructed as wood,steel,orconcretefloorsystems.Longorcurvilinearramps are usually of steel or reinforced concrete.

• 1:12maximumslope• 30"(760)maximumrise

between landings

• 30°maximum

9.06 STAIR PLANS

Straight-Run Stair• Astraight-runstairextendsfromonelevelto

another without turns or winders.• Buildingcodesgenerallylimittheverticalrisebetweenlandingsto12'(3660).

• Astairwaymaybeapproachedordepartedeitheraxially or perpendicular to the stair run.

Quarter-Turn Stair• Aquarter-turnorL-shapedstairmakesa

right-angled turn in the path of travel.• Thetwoflightsconnectedbyaninterveninglanding

may be equal or unequal, depending on the desired proportion of the stairway opening.

• Landingsthatarebelownormaleyelevelandprovidea place to rest or pause are inviting.

Half-Turn Stair• Ahalf-turnstairturns180°orthroughtwo

right angles at an intervening landing.• Ahalf-returnstairismorecompactthana

single straight-run stair.• Thetwoflightsconnectedbythelanding

may be equal or unequal, depending on the desired proportion of the stairway opening.

STAIR PLANS 9.07

Winding Stair• Awindingstairisanystairwayconstructed

with winders, as a circular or spiral stair. Quarter-turn and half-turn stairs may also use winders rather than a landing to conserve space when changing direction.

• Winderscanbehazardoussincetheyofferlittle foothold at their interior corners. Building codes generally restrict the use of winders to private stairs within individual dwelling units.

Circular Stair• Acircularstair,asitsnameimplies,hasa

circular plan configuration. Even though a circular stair is constructed with winders, the building code may allow its use as part of the means of egress from a building if its inner radius is at least twice the actual width of the stairway.

Spiral Stair• Aspiralstairconsistsofwedge-shaped

treads winding around and supported by a central post.

• Spiralstairsoccupyaminimumamountof floor space, but building codes permit their use only as private stairs in individual dwelling units.

• See9.12fortypicaldimensions.

• Windersmusthavetherequired tread dimension at a point 12"(305)infromthenarrow end of the treads.

• 6"(150)minimumatthenarrow end of the treads

• 10"(255)minimumatthenarrow end of the treads

• Theinsideradiusshould be at least twice the actual width of the stair.

• 7-1/2"(190)minimumtread dimension at a point 12"(305)infromthenarrow end of the treads.

• 9-1/2"(240)maximum riser height

• 6'-6"(1980)minimumheadroom clearance

9.08 WOOD STAIRS

A wood stair is constructed of the following elements:

• Carriagesorroughstringersaretheprincipalinclinedbeams supporting the treads and risers of a flight of stairs. The number and spacing of carriages required for a stairway depend on the spanning capability of the tread material.

• Stringersaretheslopingfinishmembersrunningalongsidea staircase, against which the risers and treads terminate.

• Treadsarethefootwaysthatspanthedistancebetweenthe supporting carriages.

• Risersaretheverticalboardsthatcloseoffthestairspaceand help make the construction rigid; some stairs have no risers.

CSI MasterFormat™ 06 43 00: Wood Stairs and Railings

• Soffit,ifdesired• Fireblocking

• Carriage• Spacer

Closed-Riser Stair with Full Stringer

• Carriagesmaybeattachedtotheir supporting beam, header, or wall framing with metal hangers or a ledger.

• Kickplateanchorsandabsorbsthe thrust of an inclined stair carriage.

• Finishwoodflooringoverplywoodtreads and risers

• Fullstringer

• Rise• Run• See9.03–9.05forriser,tread,

and nosing requirements.

• Chamferedgesofplywoodtreads for carpeting.

• See9.04–9.05forhandrail requirements.

• Metalhandrailbracket

• Wallframing• Wallfinish

• Fullstringers

• Carriages• Spacers

• Blockingasrequiredforwall finish

WOOD STAIRS 9.09

• Facestringerreceivesriser at a mitered joint.

• Facestringeristheouterstringer of a staircase; it may be housed to form a curb or be open with its upper edge cut to the profile of the treads and risers.

• Balusters• Fillerbetweenbalusters• Shoerail

• Housedstringer• Tread

• Wedge• Blocking• Carriage• Wallfinish

Housed Stringer @ Rail

• Handrail;see9.04–9.05 for requirements.

• Fillerbetweenbalusters

• Balustersdovetailedintotreads

• Housedwallstringer• Tread• Treadreturn

• Wedge• Carriages• Blocking

• Facestringer• Wallfinish Open Stringer @ RailClosed-Riser Stair with Housed Stringer

Open-Riser Stair

• Housedstringerisroutedtoreceivetheendsoftreads and risers in a series of housings; wedges are used to assure a tight fit.

• Balusterslag-boltedtocarriage

• Treadsmaybesupportedeitherbysteel angles let into the treads or by letting the planks into the carriage 1/2"(13)minimum.

• Aboxstairhasahousedstringonboth sides so that it may be more or less completely finished before being set in its final location.

• 2xor3xcarriage• 2xor3xplanktreads

• 1"to1-1/2"(25to38)overlap• Checkbuildingcodeformaximum

size of opening allowed.• Steelanglelag-boltedtocarriage

and floor structure

• Open-riserstairsdonotcomplywithADA accessibility guidelines.

• Woodriser• Woodtread

9.10 CONCRETE STAIRS

A concrete stair is designed as an inclined, one-way reinforced slab with steps formed on its upper surface. If the stair is constructed after the floor beam or wall supports, it acts as a simple beam. If it is cast with the beam or slab supports, it is designed as a continuous beam. Concrete stairs require careful analysis of load, span, and support conditions; consult a structural engineer for final design requirements.

• 1-1/2"(38)minimum@concretewalls;4"(100)minimum@masonrywalls

• Stairslabthickness;ruleofthumb:span/26• Spanisequaltothehorizontaldistancebetween

the slab supports.

• Postsupportsforhandrail• Escutcheon• Cast-in-placesleeve

• Postsorbalusters• Bracketanchoredtoconcrete

• Handrailsupportsmaybeanchoredtothetop of the stair slab or low wall, or to the edge of the stair slab.

• Castmetalnosingw/abrasivefinish

• Metal,rubber,orvinyltreadw/groovedsurface

• Stonetreadw/abrasivestrips

* Stairs require slip-resistant nosings and treads.

CSI MasterFormat 03 30 00: Cast-in-place ConcreteCSI MasterFormat 03 11 23: Permanent Stair Forming

• Edgeofstairslabmaybeturned up to form a curb or solid railing.

• See9.04–9.05forhandrail and guardrail requirements.

• Shearkey• Steeldowels

• 1-1/2"(38)maximumnosing• 1/2"(13)maximumradius• 60°minimum

• Ruleofthumbforslabthickness:span/26

• Horizontalbarsextendintosidewall• Steelreinforcementasrequired

• Beamsupport

Longitudinal Section

• Nosingbars

• 1/2"(13)radiusmaximum• 3/4"(19)radiustypical

• See9.03–9.05forriser, tread, and nosing requirements.

STEEL STAIRS 9.11

Steel stairs are analogous in form to wood stairs.

• Steelchannelsectionsserveascarriagesandstringers.• Stairtreadsspanthedistancebetweenthestringers.• Treadsmayconsistofprecastconcrete,concrete-filledsteel

pans, bar grating, or flat plates with a textured top surface.

• Pre-engineeredandprefabricatedsteelstairsareavailable.

CSI MasterFormat 05 51 00: Metal Stairs

• Steelbeamsupport

• Steelchannelstringer• Concrete-filledsteelpantreads• Steelpanlandingwithconcrete

fill• Steeltubeorchannelsupport

• Steelpantreadsw/2"(51)minimum concrete fill

• Formofpanvaries;consultmanufacturer.

• 1-1/4"x1-1/4" x 1/8" (32x32x3)anglesupports

• Steelchannelstringer; 10"(255)minimum

• Gypsumboardormetallathand plaster soffit supported on furring channels

Closed Risers

• Steelpansw/concretefillweldedto channel stringer

• Flatplatetreadswith textured top surfaces

• Checkbuildingcodeformaximumsize of opening allowed.

• Open-riserstairsdonotcomplywith ADA accessibility guidelines.

Open Risers

• Shop-fabricatedhandrailofmetalpipe;1-1/4"(32)ø

• See9.04–9.05forbuildingcoderequirements and ADA accessibility guidelines for handrails and guardrails.

• Fieldweld

• Clipanglew/anchorboltssecures each stringer to the floor structure.

• Bargratingtreads• Nosingmayconsistofacheckeredplate,

closely spaced bars, or an angle with an abrasive strip.

• Woodandprecastconcretetreads are also available.

• Steelchannelmayrestona bearing plate on masonry, or be hung on threaded rods from the floor structure above.

9.12 SPIRAL STAIRS

CSI MasterFormat 05 71 13: Fabricated Metal Spiral Stairs

• 26"(660)minimumclearwidth• Largerdiametersaresaferand

easier to climb and descend.• 90°landingplatformmaybe

a square, rectangle, or quarter circle.

• Therequiredheadroomshould be achieved within 3/4 of a circle.

• Thecenterpolemayterminate at a rail or continue up to ceiling structure.

• 42"(1065)

• Floorlevel

• 9-1/2"(240)maximum riser height

• Riserheightdependsontreadangle and floor-to-floor height.

• 6'-6"(1980)minimum headroom clearance

• Woodormetalpipehandrail• Balusters

• Baseplatemaybearonfinishflooror on floor structure below.

• Floor-to-floorheight

• Variousconnectionsareavailableto anchor the platform to the floor structure.

• Rectangularlandingplatform is secured to upper floor along one edge.

• StairrisestoanL-shapedopening and is secured directly to the upper floor structure; no platform is supplied.

• Squareplatformisfastened to the upper floor on two adjacent sides.

• Quartercircularplatform is installed in a circular floor opening.

Stair Connections

• 221/2°,27°,30°• 7-1/2"(190)minimumatapoint12"(305)infromthenarrowend of the treads.

• Steeloraluminumtreadsmaybea checkered or abrasive-coated plate, bar grating, or a concrete- or terrazzo-filled pan.

• Woodtreadsrequireasteelsubstructure. The treads may be a hardwood or of plywood for a carpeted finish.Plan and Elevation Stair Treads

Representative Sizes and Dimensions of Spiral Stairs* Tread Angle No. of Treads Riser Height Headroom in 360°

221/2° 16 7"(180) 7'-0"(2135) 27° 13 7-1/2"to8"(190to205) 6'-9"(2055) 30° 12 8-1/2" to 9-1/2"(215to240) 6'-9"(2055)

*Consult manufacturer’s literature to verify these dimensional guidelines.

Stair Well Landing Width Center Pole/ Diameter Opening Size Pole to Rail Base Plate Diameter

60"(1525) 64"(1625) 32"(815) 26"(660) 4"/12"(100/305)64"(1625) 68"(1725) 34"(865) 28"(710) 4"/12"(100/305)72"(1830) 76"(1930) 38"(965) 32"(815) 4"/12"(100/305)76"(1930) 80"(2030) 40"(1015) 34"(865) 4"/12"(100/305)88"(2235) 92"(2335) 46"(1170) 40"(1015) 6"/12"(150/305)96"(2440) 100"(2540) 50"(1270) 44"(1115) 6"/12"(150/305)

LADDERS 9.13

Laddersareusedprimarilyinindustrialconstruction and in utility and service areas. They may also be used in private residential construction where space is extremely tight and traffic is minimal.

The drawings on this page illustrate ladders built with metal components. The ladder forms may be translated into wood construction.

Safety considerations include:• Properriserheight• Adequatetoespace• Adequatesupportforstringsandrailings• Slip-resistanttreads

• Steelchannelstringer• Checkeredsteelplate

or bar grating• Anglebrackets

• Aplatformisrequiredtoclear top of parapet.

• Bargrating or 3/4"(19)roundbars @3'-0"(915)o.c.

CSI MasterFormat 05 51 33: Metal Ladders

• Itismoreconvenienttoaccessladder from the side rather than through the hand bars.

• 2'-0"(610) minimum width

• Supportangles@10'-0"(3050)o.c.maximum

• 1'-6"(455)minimum

• Rungsmaybe3/4"(19)roundbarsor1"(25)øpipes.

• Stringersmaybechannels,angles, or flat bars.

• Anglebracketsboltedtofloorstructure

• 3'-0"(915)highhand bars

• 12"to13-1/2" o.c. (305to345)

• 7"(180)minimum

• 12"(305)+/– to first rung

Vertical Ladders

Ship’s Ladder

• 1-1/4"(32)øpiperailing; secure to wall structure or return to stringer at top.

• 6"(150)todoorway

• 3"to6"(75to150)

• 10-1/2"to12" (265to305) rise

• 60°to75°

9.14 ELEVATORS

Elevators travel vertically to carry passengers, equipment, and freight from one level of a building to another. The two most common types are electric elevators and hydraulic elevators.

Electric ElevatorsElectric elevators consist of a car that is mounted on guide rails, supported by hoisting cables, and driven by electrichoistingmachineryinapenthouse.Gearedtractionelevatorsarecapableofspeedsupto350fpm(1.75m/s)andaresuitableformedium-risebuildings.Gearlesstractionelevatorsareavailablewithspeedsupto1200fpm(6m/s)andtypicallyservehigh-risebuildings.

• 16'-0"to20'-0"(4875to6095)

• Topfloor

• Hoistingcableisoneofthewirecablesorropesusedforraising and lowering an elevator car.

• Hoistwayistheverticalenclosedspaceforthetravelofone or more elevators.

• Travelingcableisoneoftheelectriccablesconnectinganelevator car to a fixed electrical outlet in the hoistway.

• Guiderailsaretheverticalsteeltrackscontrollingthetravel of an elevator car or counterweight; they are secured to each floor with support brackets.

• Counterweightsarerectangularcast-ironblocksmounted in a steel frame to counterbalance the load placed on the hoisting machine by an elevator car.

• Alimitswitchautomaticallycutsoffcurrenttoanelectric motor when an elevator car has passed a given point.

• Riseortravelistheverticaldistancetraversedbyanelevator car from the lowest to the highest landings of the hoistway.

• Bottomfloor

• 5'-0"to11'-6"(1525to3505)

CSI MasterFormat 14 20 00: Elevators

• Apenthousehousesthehoistingmachinery on the roof of a building.

• Acontrolpanelcontainsswitches,buttons, and other equipment for regulating the hoisting machinery.

• Thehoistingmachineryforraisingand lowering an elevator car consists of a motor-generator set, traction machine, speed governor, brake, driving sheave, and gears, if used.

• Heavysteelmachinebeamssupportthe hoisting machinery for an elevator.

• Drivingsheaveisthehoistingpulley.• Idlesheavetightensandguidesthe

hoisting cables of the elevator system.

• Landingistheportionofaflooradjacent to an elevator hoistway, used for the receiving and discharge of passengers or freight.

• Elevatorcarsafetyisamechanicaldevice for slowing down and stopping an elevator car in the event of excessive speed or free fall, actuated by a governor and clamping the guide rails by a wedging action.

• Hoistwaydoorbetweenahoistwayandan elevator landing is normally closed except when an elevator car is stopped atthelanding;7'-0"and8'-0"(2135and2440)heightsaretypical.

• Bufferisthepistonorspringdevice that absorbs the impact of a descending elevator car or counterweight at the extreme lower limit of travel.

• Elevatorpitistheportionoftheshaft that extends from the level of the lowest landing to the floor of the hoistway.

ELEVATORS 9.15

Hydraulic ElevatorsHydraulicelevatorsconsistofacarsupportedbya piston that is moved by or moves against a fluid under pressure. A penthouse is not required, but the hydraulic elevator’s lower speed and piston length limit its use to buildings up to six stories in height.

• Guiderail

• Hoistwayoffire-resistiveconstructionmustextend to the underside of a fire-resistive roof, or atleast3'(915)aboveanon-fire-resistiveroof.

• Hydraulicpiston

• Machineroomhousesthehoistingmachinery,control equipment, and sheaves for raising and lowering an elevator car; a location at or near the bottom landing is preferred.

• Elevatorpit

• Pistoncylinderwell; depth equals rise or travel+4'to7'(1220to2135)

• Thesedimensionalguidelinesareforpreliminaryplanning only. Consult the elevator manufacturer for specific sizes, capacities, and dimensional and structural support requirements.

• 3"to1'-6"(75to455) depending on elevator operation

• 5"(125)

• 8"(205)

• Allow4"(100)forbeamto supportguiderails@eachfloor

• 3'-0",3'-6",4'-0" (915,1065,1220)

Elevator Car Dimensions

• Varieswithcarheightandspeed; allow12'to16'(3660to4875)

• Topfloor

• Verticaltravel:70'-0" (21m)maximum

• Bottomfloor

• Variesfrom4'to6' (1525to1830)

Rated Load Elevator Car DimensionsLb. (kg) A B

2000(907) 6'-0"(1830) 5'-0"(1525)2500(1135) 7'-0"(2135) 5'-0"(1525)3000(1360) 7'-0"(2135) 5'-6"(1675)3500(1588) 7'-0"(2135) 6'-2"(1880)4000(1815) 5'-8"(1725) 8'-9"(2665)

Limited Use/Limited Access ElevatorsLimitedUse/LimitedAccess(LU/LA)elevatorsaresmallhydraulicelevators designed for installation in new or existing low-rise structures.LU/LAelevatorsarelimitedto25'(7620)oftravelataspeedof30fpm(0.55km/h),aloadcapacityof1400lb.(635kg),andacabfloorareaof18sf(1.67m2).Theycanoperateonsingle-phase power and require less pit depth and overhead space than do regular commercial elevators.

9.16 ELEVATORS

Elevator LayoutThe type, size, number, speed, and arrangement of elevators are determined by:• Typeofoccupancy• Amountandtempooftraffictobecarried• Totalverticaldistanceoftravel• Round-triptimeandspeeddesired

• Banksorrowsofelevatorsinahigh-risebuildingarecontrolledbya common operating system and respond to a single call button.

• Elevatorsshouldbecentrallylocatednearthemainentrancetoabuilding and be easily accessible on all floors, but also be placed off of the main circulation path.

• Twoormorehoistwaysarerequiredforfourormoreelevators.

• Consultelevatormanufacturerforrecommendedtype,size,layout, controls, and installation requirements and details.

• Consultthebuildingcodeforstructuralrequirementsandshaftway requirements for fire separation, ventilation, and soundproofing.

ADA Accessibility Guidelines• Visibleandaudiblecallsignalsorlanternsshouldbecenteredatleast72"(1830)abovethefloorateachhoistwayentranceandbe visible from the adjacent floor area.

• RaisedcharactersandBraillefloordesignationsshouldbeprovided on both jambs of elevator hoistway entrances and be centeredat60"(1525)abovethefloor.

• Callbuttonsforrequestinganelevatorshouldbecentered42"(1065)abovethefloorineachelevatorlobby.

• Elevatordoorsshouldbeprovidedwithanautomaticreopeningdevice if the door becomes obstructed by an object or person.

• Elevatorcarsshouldbesizedtoallowwheelchairuserstoenterthe car, maneuver within reach of controls, and exit from the car.

• Controlbuttonsshouldbe3/4"(19)intheminimumdimension,be arranged with numbers in ascending order, with columns of numbers reading from left to right.

• Floorbuttonsshouldbelocatedatleast35"(890)abovethefloorandbenohigherthan48"(1220)forfrontapproachand54"(1370)forparallelapproach.

• RaisedandBrailledesignationsshouldbeplacedimmediatelytothe left of the button to which the designations apply.

• Audibleandvisiblecarpositionindicatorsshouldbeprovidedineach elevator car.

• 1.5xcardepthor 10'(3050)minimum

• 1.75xcardepth

• 2xcardepthor 12'(3655)minimum

• Eightcarsper row maximum

• 68"(1725)minimumwidth for cars with side opening doors; 80"(2030)minimumforcars with center opening doors

• 51"(1295)minimumclear car depth

• 36"(915)minimumcleardoorway opening

ESCALATORS 9.17

Escalators are power-driven stairways consisting of steps attached to a continuously circulating belt. They can move a large number of people efficiently and comfortably between a limited number of floors; six floors are a practical limit. Because escalators move at a constant speed, there is practically no waiting period, but there should be adequate queuing space at each loading and discharge point. Escalators may not be used as required fire exits.

• 2"(51)

• Escalatorsrequiresupportsat both ends; intermediate supports may be required whentheriseexceeds18'(5485).

• Thesedimensionalguidelines are for preliminary planning only. Consult the escalator manufacturer for specific sizes, capacities, and dimensional and structural support requirements.

CSI MasterFormat 14 30 00: Escalators and Moving Walks

• 7'-6"(2285) • 1.732xrise • 8'-0"(2440)

• 7'-6"(2285) minimum headroom

• Rise

• 3'-2"(965)• 2'-8"(815)

• Atrusssupportstheescalator and provides space for the necessary mechanical equipment.

• Movingsidewalksarepower-driven,continuouslymovingsurfaces, similar to a conveyor belt, used for carrying pedestrians horizontally or along low inclines.

• 2"(51)fromtruss to edge of beam

• Nominalwidths: 32",40",48" (815,1015,1220)

• Stepwidths: 24",32",40" (610,815,1015)

• 3'-0"(915)

• 3'-8"(1120)

• Deckwidths: 4'-0",4'-8",5'-4" (1220,1420,1625)

• Nominalwidths: 32",40",48" (815,1015,1220)

• Widthsofwalk: 24",32",40" (610,815,1015)

• Deckwidths: 4'-4",4'-8",5'-4" (1320,1420,1625)

• 3'-0"(915)

• Intermediatesupportsasrequired by span

• Depthofsupportingtruss:3'-6"(1065)