Ch 7 - Wood Construction Flashcards
Engineered wood pros & cons
Advantages: strength and cost efficiency
Disadvantages: quick and unpredictable failure under fire conditions
Glulam beams
Frequently used in heavy timber construction
React similar to solid Timbers under fire conditions
Fire has essentially no effect on adhesives used
LVL - laminated veneer lumber
Sheets of veneer from outer portion of log, laminated in parallel alignment
PSL - parallel strand lumber
Strongest of structural composite lumbers, heavy loaded columns and long spans
Plywood
Several thin layers (veneers) glued together at right angles
OSB
Long, strand like wood particles glued together and oriented in the same direction
Particleboard
Wood particles bonded with synthetic resins
Not used for structural elements
Floors of mobile homes
Composite panels
Face and back panel of OSB/plywood bonded to a central core material, typically plastic foam (polyurethane or polystyrene)
R-value
A measure of the ability of a material to insulate
Materials used for fire stopping
2 inch nominal lumber
Gypsum board
Cement board
Mineral wool & glass fiber insulation
Required firestopping locations
Within stud walls at floor and ceiling
Connection point between vertical stud spaces and horizontal spaces
Between stair stringers
Behind fascia
Exterior sheathing
Plywood, OSB
Building wrap
Layer between the sheathing and the siding that acts as a vapor barrier
Foam insulation
Glass wool or rock wool
Fiberglass
Noncombustible to slow fire spread in void spaces
Siding materials
Aluminum
Vinyl
Asphalt shingles
Stucco
Wood shingles
Various levels of combustibility
Brick or stone veneer walls
Must be tied to wood frame at 16 inch intervals
No structural support
May create void spaces between veneer and sheathing for fire spread
Pyrolysis of wood begins at…
392°F
Factors affecting combustion properties of wood
Ignition temperature
Heat of combustion
Surface to mass ratio
Fire retardant treatment of wood
Void spaces
Ignition resistant construction
Fire resistant roof coverings
Noncombustible or fire rated exterior walls
Different than fire-resistive construction (structural members are not resistant)
Areas with wildland fires
Ledger board
Horizontal framework member attached to beams to support floor joists, used in balloon frame
Balloon frame
Wall studs are continuous from top to bottom
Platform framing
Studs are not continuous
First constructed as a platform to attach studs, second floor platform attached to studs
Creates fire stops at each floor level
Primary characteristics of heavy timber (type IV)
Thicker dimensions of structural wood members
Does not allow combustible concealed soaces
Post and beam
No traditional stud wall construction
Larger dimension posts and beams
Posts usually exposed on interior, eliminating void spaces
