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1WoodMatlsConstruction2.pptx

CMST 102

Dr. Charner Rodgers

WOOD MATERIALS & CONSTRUCTION

Lumber

Wood construction is common for many houses throughout the world and considered to the most cost-effective and best approach for housing. Wood frame is used for approximately 90% of the houses constructed in the US.

Industry

Commodity

$270 billion/year

Consumption +50% by 2050

Timber to lumber

Manufacturing

Felling

Debarking/bucking

Headrig

Bandsawing

Resaw

Seasoning

Planing

Stamping/banding

Characteristics

Nominal 2x4

Actual 1.5x3.5

Board foot

Grading

Factors

Dimension lumber categories

Stamps

Treated

Prevent destruction

Increase service life

Preservatives

Fire retardants

Heat treated

Pressure treated

Wood Products

MANUFACTURED WOOD PRODUCTS

Glulam

Terminology

(handout)

Fiber reinforced glulam beams

Pedestrian bridge-Norway

Todaiji temple-largest wood structure

Conceptual model

Glulam

Manufacture

Engineered Beams (composite) http://www3.telus.net/selkirk99/selkirk/Beams/beams.html

LVL beam used as kitchen counter

PSL Beam

LVL beams meet to form medallion

Joists

Save time

No special tools

Less wasteful

No warp, twist or shrink

Quick installation

Knock-out holes

Trusses and panels

Plywood and OSB

Layers of veneer with grain alternating

Glue between layers

Heated and pressed

strong in all directions

Wood Frame Construction

WOOD FRAME CONSTRUCTION

System of construction using many small and closely spaced members that can be assembled by nailing. It is the standard for U.S. suburban housing. The balloon-frame house with wood cladding, invented in Chicago in the 1840s, aided the rapid settlement of the western U.S. In North America, with its abundant softwood forests, the framed building enjoyed an extensive revival after World War II in the form of platform frames.

In platform framing, each floor is framed separately, as contrasted with balloon framing, in which the studs extend the full height of the building. Freed from the heavy timbers of the post and beam system, platform framing offers ease of construction. Carpenters first fabricate a floor, which consists of wood joists and subflooring. The floor often serves as a working platform on which the stud wall frames are fabricated in sections and then lifted into place. On top of this is placed a second floor or the roof.

The roof is formed of rafters or wood trusses. Framed structures traditionally were constructed individually at each house site; today many of the framing elements are mass-produced elsewhere and assembled on-site.

The parts and pieces…

Platform Framing

Platform Framing details

Configuration & Spacing

Studs

Load bearing walls (supporting one/multiple floors)

Nonload bearing walls

Joists

Rafters

Terms

Joist: horizontal or sloped framing member

Rafter: sloping framing member for the roof

ceiling joist

floor joist

stud

rafter

Stud: vertical framing member

“Stick built”– one piece at a time

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Wall Framing

Wood Stud Walls

2 x 4’s or 2 x 6’s

16” or 24” o.c.

Insulation

vapor barriers

Interior finish (gypsum)

Header

Sill

Cripple/Jacks

sill

header

cripple/jacks

sill cripple/jacks

stud

jack stud

bottom plate

top plate

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Plates - Horizontal members at top & bottom of studs

@ Sill

@ Wall

@ Foundation

stud

bottom plate

top plate

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Blocking

Solid piece of isolated wood (stud) placed between framing members (walls, floors, roofs).

Usually for support or attachment of something else.

blocking

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Floor Framing

Wood Joist System

Relatively small joist members (2x6, 2x8, 2 x10)

closely spread

(12”, 16”, 24” o.c)

Short spans for subflooring, underlayment and gyp-board ceilings

Bridging

Material between framing members (continuous) to evenly distribute loads

Keeps framing members from twisting

Solid blocking

Diagonal bridging

blocking

bridging

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Floor Framing

Example: joist size, orientation and

spacing for the following plan

Sample Floor Joist Span Table

Sample Floor Joist Table

Douglas Fir-Larch (lumber species)

No. 1 and No. 2 (lumber grade)

All joists are bridged

12’-0”

13’-0”

Floor Systems - Floor Projections

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Floor Systems - Floor Openings

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Floor Systems - Partition Connections

Partition parallel to joists

Partition perpendicular to joists

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Partition perpendicular to joists

Partition parallel to joists

Floor Systems - Partition Connections

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Roofs

Types and slopes

Roofs

Rafter Example:

Wood Roof Framing Table for Maximum Roof Rafter Spans

Sheathing

- material covering the framing members (roof, floor & walls)

Plywood (typically 4’ x 8’ modular sheets) roll sliced lumber

OSB (oriented strand board) reconstituted (recycled) wood

Boards (cut lumber)