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