Structural Components Chapter 26 Structural Components

Links for Chapter 26 Floor Construction Wall Construction Roof Construction Environmental Design Related Web Sites

Conventional Floor Framing Floor joists range from 2” X 6” to 2” X 14” and spaced at 12”, 16”, or 24” Mudsill rests on the masonry foundation Provides a base for all framing Attached to foundation with anchor bolts Either 3/4” or 5/8” in diameter

Conventional Floor Framing

Conventional Floor Framing Girder (beam) is used to support the floor A flitch beam consists of steel plates bolted between wood members Glu-lam beams are laminated with sawn lumber and more structurally stable Engineered wood girders consists of laminated veneer strips glued together

Conventional Floor Framing Girder (beam) is used to support the floor Steel beams are used for long spans and do not shrink or expand A post is used to support beams and are 4” X 4” or 6” X 6” depending on beam width Steel posts do not draw moisture and remain a more true size

Conventional Floor Framing

Conventional Floor Framing Joists support the subfloor Joists that span past a girder are cantilevered Joists shaped as an “I” are called trusses Laminated veneer lumber is used for heavy loads with single or multi-spans Engineered joists support larger loads with less material

Conventional Floor Framing

Engineered Floor System

Floor Bracing Joists will tend to roll as loads are applied Blocking is used at the center of the joist span to help transfer lateral loads Sheathing is placed over the joists to form the subfloor Face grain should be perpendicular to the floor joists

Floor Bracing

Post-and-Beam Construction Girders are supported on a post and concrete pier Usually 4” X 6” Spaced at 48” o.c. Flooring is 2 X 6 or 2 X 8 tongue and groove boards or 1 3/32” plywood

Post-and-Beam Construction

Framed Wall Construction Bearing walls support the weight of the roof or other floors Extra support is required under it Nonbearing walls have no structural purposes Sometimes called partitions Can be removed without causing damage

Framed Wall Construction

Framed Wall Construction Sole plate is the bottom plate and disperses the wall load to the floor system Studs are vertical framing members to transfer load from top of wall to floor system Top plates are used to hold the wall together Two are required on bearing walls and must lap by at least 48”

Framed Wall Construction Sheathing is used as an insulator against weather Double-wall construction is when sheathing is applied to an exterior wall Single-wall construction is when a vapor barrier and no sheathing is used on an outside wall

Framed Wall Construction Sheathing helps walls not to twist or rack Shear panel resists these forces Let-in braces stiffen stud walls

Framed Wall Construction Header is an opening above a door or window Trimmers support headers Subsill is on the bottom of a window

Roof Construction Eave on the roof extends beyond the walls Cornice is the covering on the eaves Fascia is trim placed at the end of the rafters Roof sheathing covers structural members Skip sheathing is used with either tile or shakes

Roof Construction

Roof Construction Finished roofing is the weather protection system Pitch describes the slope of the roof Rise is the vertical distance of the slope Run is the horizontal distance of the slope Span is the horizontal measurement between inside edges of supporting walls

Roof Construction

Roof Construction Conventional framing involves the use of wood members placed in a repetitive fashion Ridge board is the horizontal member at the ridge and runs perpendicular to the rafters Rafters are the sloping members used to support roof sheathing and finished roofing

Roof Construction

Roof Construction Common rafter spans and supports the roof loads from ridge to top plate Bird’s mouth is the notch cut in rafter where the rafter intersects a beam or bearing wall Hip rafter is used on the slopes of the hip Valley rafter is used on the slopes of the valley

Roof Construction

Roof Construction Ceiling joists span between top plates and bearing walls Ridge braces are used to support downward action of the ridge board Ridge beam supports the upper end of the rafter/ceiling joists

Roof Construction

Truss Roof Construction Truss is a component used to span large distances without intermediate supports Top chord supports the roof sheathing Bottom chord resists outward thrust of the top chord and supports Webs span between top and bottom chords Ridge blocks provide nailing surface for roof sheathing

Truss Roof Construction

Truss Roof Construction Cantilevered truss is when the truss extends beyond the support Hip truss is used to form hip roofs Vaulted or scissors truss have inclined bottom chords Metal hangers keep floor, ceiling, and roof members from separating

Truss Roof Construction

Truss Roof Construction

Environmental Design It is important to be familiar with chemicals that are commonly found in the home Formaldehyde is a colorless gas found in most resin-based construction products It can cause irritation to nose, throat, and eyes and cause headaches, coughing, and fatigue

Environmental Design Optional material can be used that does not contain harmful chemicals Grass-based boards can be used for sheathing Low-toxic products that repel moisture All natural carpets reduce allergy reactions

Environmental Design Gas and oil heaters are more efficient, they do produce toxic chemicals and reduce the quantity of natural resources Electric heaters are nontoxic yet are more expensive and less efficient

Related Web Sites American Lumber Standards Commission, Inc. - www.alsc.com Gypsum Association - www.gypsum.org The Masonry Society - www.masonrysociety.org Wood Truss Council of America- www.woodtruss.com