Transcript Chapter 28

Chapter 28
Structural Components of Framed
Construction
Introduction
• All phases of drafting have their own
terminology
– Terms for basic structural components of
residential construction refer to the:
• Floor
• Wall
• Roof components
Floor Construction
• Conventional floor framing
– Involves the use of members 2" wide placed
one at a time in a repetitive manner
– Mudsill, or base plate rests on masonry
foundation and provides a base for all framing
– Girder (i.e., beam) support floor joists
– Laminated girders are used in areas a large
open space is desirable (e.g., basements)
Floor Construction (cont’d.)
• Conventional floor framing (cont’d.)
– Engineered wood girders and beams are
common in residential construction
• Laminated veneer lumber (LVL) offers superior
performance and durability
– Steel girders are used where foundation
supports must be kept to a minimum
– Posts are used to support the girders
• Wooden posts or steel columns
Floor Construction (cont’d.)
• Conventional floor framing (cont’d.)
– Floor joists are repetitive structural members
used to support the subfloor (i.e., rough floor)
• A cantilever is a joist that extends past its support
– I-joists are a high-strength, lightweight, costefficient alternative to sawn lumber
• Form a uniform size
• Have no crown
• Do not shrink
Floor Construction (cont’d.)
• Conventional floor framing (cont’d.)
– Open-web floor trusses are a common
alternative to using sawn lumber for floor joists
– Steel joists are used to support the floor
• A 6" x 6" x 54 mil L-clip angle is bolted to foundation
to support the track that will support the floor joist
– Floor bracing keeps joists from rolling over on
its side (e.g., rim joist or blocking)
– Floor sheathing forms the subfloor
Floor Construction (cont’d.)
• Conventional floor framing (cont’d.)
– Floor underlayment provides a smooth impactresistant surface
– Common engineered stamp markings
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Grade designations
Span rating
Bond classifications
Thickness
Group number
Floor Construction (cont’d.)
• Post and beam construction
– Mudsill is installed as with platform
construction
– Girders are placed supporting floor decking
• Post support girders
– Decking material laid over girders forming the
subfloor
• Usually finished similarly to conventional decking
with a hardboard overlay
Framed Wall Construction
• Bearing walls
– Support itself and the roof weight or floors
constructed above
– Requires support under at the foundation or
lower floor level (e.g., girder or bearing wall)
• Nonbearing walls (i.e., partitions)
– Serve no structural purpose
– Used to divide rooms
Framed Wall Construction (cont’d.)
• Wall construction
– Made of wood or engineered lumber
– Sole or bottom plate helps disperse loads from
wall studs to floor system
• Hold studs in position
– Studs are vertical framing members
• Transfer loads from top of the wall to floor system
Framed Wall Construction (cont’d.)
• Wall construction (cont’d.)
– Wall sheathing insulates against weather and
provides backing for exterior siding
• When used on exterior walls it provides double-wall
construction
• In single-wall construction, wall sheathing is not
used, and siding is attached over a vapor barrier
– Structural wall sheathing (e.g., plywood) is
used to resist a wall’s twisting or racking
Framed Wall Construction (cont’d.)
• Wall construction (cont’d.)
– Let-in braces are an alternative to using
engineered materials for shear panels
– Blocking helps provide stiffness
• No longer required unless a wall exceeds 10′ high
Framed Wall Construction (cont’d.)
• Wall construction (cont’d.)
– Framing members for wall openings
Framed Wall Construction (cont’d.)
• Wall construction (cont’d.)
– Modular wall framing
• Components are shipped in containers
• Exterior wall protection
– Prior to installing siding, the home is covered
with a weather-resistant exterior wall envelope
• Water barriers
• Moisture and air barriers
• Exterior caulking
Framed Wall Construction (cont’d.)
• Interior wall protection
– Vapor barrier
• Membrane placed on warm side of walls and
ceilings between drywall and insulation
– Interior caulking
• Specified to reduce air infiltration
– Interior finish
• Gypsum board, green board, or sound-deadening
board
Roof Construction
• Common roof terms:
– Eave
– Cornice
– Eave or bird blocking
– Fascia
– Ridge
– Sheathing
– Finishing roofing
– Flashing
– Roof pitch
dimensions
Roof Construction (cont’d.)
• Conventionally framed roofs
– Involve the use of wood members placed in
repetitive fashion
– Stick framing involves the use of members
(e.g., ridge board, rafter, and ceiling joists)
Roof Construction (cont’d.)
• Truss roof construction
– A truss is used to span
large distances without
intermediate supports
• Prefabricated or job built
Roof Construction (cont’d.)
• Truss roof construction (cont’d.)
– Truss gains its strength from triangles formed
throughout it