*Bk 29- Building Construction Flashcards
Lightweight truss construction- Strength is obtained from multiple members that are in ___________ and ___________
Compression and tension
A single lightweight truss structural member can span how far?
70 feet
The amount of time that a structure can be considered structurally strong is dependent on what 3 factors?
- Type of construction
- How long fire has been burning
- Fire intensity
What are the six types of roof styles explained in book 29?
- Gable
- Flat
- Hip
- Bridge truss
- Arch truss
- Sawtooth
Gable roofs (conventional)- size and span of rafters? Include steep pitch roof.
- 2x6” or larger. 16” to 24” on center
2. Steep pitch- 2x6”. 36” on center
What gauge is the most common metal gusset plate?
How long are the prongs?
- 18 gauge
2. 3/8”
Lightweight trusses- Eighteen-gauge “roof truss clips” may be found nailed to the bottom chord of every how many trusses?
3-5 trusses
Common “on-center” spacing for truss rafters is?
24” on center
Can interior partition walls support the truss at any point along the bottom chord?
No
What are the strong areas of a conventional gable roof?
Ridge and bearing wall
Newer roofs use ______inch or ______ inch plywood as a decking instead of 1 x 4 inch or 1 x 6 inch space sheathing
3/8 or 1/2”
What are the dimensions of decking used in space, straight and diagonal sheathing?
1x4” or 1x6”
What type of rafter is utilized where two roof lines join together?
Valley rafter
Gable (conventional)- size of ridge board (if present)
1x6” or 2x6”
Hip (conventional)- size and span of rafters? Include steep pitch.
Size of ridge board?
- 2x6” or larger. 16, 24” on center
Steep pitch- “Rough cut” 2x3 or 2x4”. 36” on center - Ridge- 2x6” or larger
What are the strong areas of a conventional hip roof?
Ridge board, valley rafters, hip rafters, and the area where rafters cross the outside walls
Bridge truss roof- Wooden truss members are what size?
2x12” lumber
In truss construction, the top chord is in _______ and the bottom chord is in _______
Compression or tension?
- Compression
2. Tension
Bridge truss- What is the rafter size? What type and size sheathing will you find?
Rafters- 2x6” or larger
Sheathing- 1x6” diagonal or straight
Per the earthquake ordinance, what cutoff year would you find straight sheathing?
What about diagonal sheathing?
- Pre 1933
2. Post 1933
Bowstring arch truss- size of arch members?
Rafter size?
Sheathing size?
- 2x12” or 2x14”
- 2x6” or larger
- 1x6” straight or diagonal (1933)
Lamella arch roof- size of wood framing?
Size of sheathing?
- 2x12”
2. 1x6” sheathing
Lamella arch roof- total roof collapse may occur if fire removes more than ______% of the roof structure.
20%
Which arch truss roof uses metal tie rods to offer lateral support for the walls of the building?
Tied truss arch
Tied truss arch- size of tie rods?
5/8” diameter
Tied truss arch- size of top chord members?
Rafter size?
Sheathing size?
- 2x12” or larger
- 2x10” or larger
- 1x6” straight or diagonal (1933)
What is the primary hazard of a tied truss arch roof?
Failure of metal tie rods and turnbuckles
Sawtooth roof- size of rafters?
Size of sheathing?
- 2x8” or larger
2. 1x6” or 1/2 plywood
Conventional flat roof- size of rafters?
Size of sheathing?
- 2x6” or larger
2. 1x6” or plywood (newer)
What are the four types of construction for a lightweight flat roof?
Wooden I-beam
Open web
Metal gusset plate
Panelized
What thickness is plywood found in on a newer conventional flat roof?
3/8” to 5/8”
Wooden I-beam- size of chords?
Material and size of stem?
- 2x4” or 2x3”
2. 3/8” plywood or OSB
What is the term for when the joints of the plywood on a roof are staggered (every 4’) similar to a masonry wall?
Diaphragm nailing
What is the common on-center spacing for wooden I-beam, metal gusset plate, open web trusses?
24”
How far are nailing blocks spaced apart?
4’ apart
The steel tube web members in an open web truss roof are prefabricated to what size?
1-2”
Open web roof- span of trusses?
70’ possible
What gauge are metal gusset with prongs that produce 3/8” penetration?
18 gauge
Metal gusset plate roof- up to what span in possible?
80 feet
Metal gusset plate roof- commercial building plywood thickness?
Plywood thickness for dwellings?
- 1/2”
2. 3/8” or 1/2”
What are the four major components that make up a panelized roof?
- Beams
- Purlins
- Rafters
- Plywood
What is the thickness of plywood used on panelized roofs?
1/2”