Wood Construction

CTC-375

Wood

• Lumber– Any wood cut into a size and shape used as a

building material– Timber – lumber with smallest dimension >5”– Board - <2” thick, at least 2” wide– Dimension - >2” thick, <5” thick, 2+” wide– Beam & stringer - >5” thick, 8”+ wide– Post & Beam – lumber approximately square

• 5+” thick and wide

• Rough sawn lumber– Sawn on all four sides to a nominal thickness and

width

• Dressed lumber– Sanded on 1 -4 sides– Called by nominal size– Sanding takes ¼” off per side

• Available in sizes from 8 – 16 feet– Studs also available at 92” – gives 8’ ceiling height

• Types of wood construction– Post & Beam

• Wooden frame provides structural support• No interior bearing walls• Posts must be attached to foundation

– Balloon Framing F 13-4• Exterior walls are continuous from foundation to roof• Floors are attached to the walls• Revived in 1980’s as solar power gained popularity• Need to place fire breaks in the walls

– Platform Framing F 13-3• Walls rest on floors• Floor is built to edge of foundation then sheathed • Wall is built on top of floor• Walls have single bottom plate and double top

plate for strength• Fire blocks at every floor

• Panels or module construction– Structural Insulated Panels (SIP)

• Can be walls or roof systems

– Conventional floor system but walls are constructed off site in 4x8 panels and hauled to site

– Allows for windows, doors to be installed at same time as walls

– Must have a flat surface

Construction

• Hurricane clips for roof

• Anchor bolts and tie downs for foundation-frame connections

• Blocking– Where do you place blocking?

• Joist Bridging– Makes floor into a system

Floor Systems

– Conventional 2x construction• Box beam surrounds joists• Girders are built up from 2x stock• Joists are 2x stock 16” o.c.• ¾” sheathing is glued and screwed onto joists

– Can use 5/8” sheathing but total floor must = 1.25”

– Engineered Lumber• I-joists – 2x3 top & bottoms with OSB web

– Long and strong – Can span 40 – 60 feet – eliminates interior bearing walls

• Floor Trusses– Usually used in commercial buildings

• Provide long spans

• Holes in Joists – Holes only in center of joist (neutral axis) and

only within 1/3 of span of end– Diameter not more than 1/3 of height or be

closer than 2” from an edge

Roof Trusses

• Components– F 13-12– Truss types F 13-13– Erection F 13-14– Bracing F 13-15

Timber Construction

• F 13-24– Post and beam on a larger scale– Connections F 13-25