Chapter 28

1. Chapter 28 Structural Components of Framed Construction

2. Introduction • All phases of drafting have their own terminology • Terms for basic structural components of residential construction refer to the: • Floor • Wall • Roof components

3. 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)

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. Framed Wall Construction (cont’d.) • Wall construction (cont’d.) • Framing members for wall openings

14. 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

15. 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

16. Roof Construction • Common roof terms: • Eave • Cornice • Eave or bird blocking • Fascia • Ridge • Sheathing • Finishing roofing • Flashing • Roof pitch dimensions

17. 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)

20. Roof Construction (cont’d.) • Truss roof construction • A truss is used to span large distances without intermediate supports • Prefabricated or job built

21. Roof Construction (cont’d.) • Truss roof construction (cont’d.) • Truss gains its strength from triangles formed throughout it