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, cost-efficient 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 impact-resistant surface
– Common engineered stamp markings • 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