L03 - Light wood frame construction Flashcards
Label the parts of a tree from its first year of growth
Pith
Heartwood
Sapwood
Bark
Tree’s first year’s growth (very very core of tree - from then on, every single year tree puts on rings)
Pith
Lifeless central portion (dead sapwood)
- Still offers structural portion of tree
Heartwood
Living layers that supply nutrients to leaves
Sapwood
Protective layer of dead cells
Bark
The __________ of some tree species such as cedar is naturally resistant to decay and insect attack.
heartwood
True or False:
The heartwood of some trees (eg. cedar) is naturally resistant to decay and insect attack
True
How much water is within a timber after being sawn from a log and what happens to the wood after?
approx. 30%
The ‘bound water’ evaporates, and the wood begins to shrink. As it dries, grows stiffer and stronger
For framing, moisture content (MC) should be no more than ___ (max per NZBC - NZ Building Code)
18%
Why should the MC be no more than 18% (max per NZBC)?
If above, then dead fungi can thrive and then begin to degrade and break down cellulose
- cause structural damage
What are some timber defects?
Tight and dead knot and splits and checks
Laminated wood
Large structural members often made by gluing smaller pieces together
What is an advantage of laminated wood?
Can achieve shapes (curves) and sizes not possible in nature
Quality can be controlled - defects removed
what is glue laminated also known as?
Glulam
A “__________ beam” is similar to a built-up beam except that the middle element is steel plate rather than timber.
flitch
True or False:
Laminated wood can control the quality and remove defects?
True
True or False:
Plywood is a panel product comprised of glued layers of wood veneer with grain direction alternated from layer to layer for added strength.
True
What does OSB stand for?
Oriented strand board
(long strands of wood compressed/glued into layers)
Particleboard
Wood particles compressed/glued
Medium Density Fibreboard (MDF)
Tiny wood fibres compressed/glued
In NZ, the most prevalent timber framing treatment used for top plates, studs, joists etc is “H____”
1.2, H1.2
H3.1 is used for what?
Painted weatherboard cladding
Battens within cladding cavity systems
In NZ, the level of wood preservative required for exposed rafter endings is ______.
H3.2
True or False:
Treated (H3.2) plywood is often used as a DPC (damp-proof course)
False
True or False:
H5 is for exposed posts, braces and piles
True
True or False:
Trusses are either pre-engineered or customised using computer software
True
Wood I-Joists
Comprised of top and bottom flanges (solid lumber or panel products) with plywood or OSB web products)
True or False:
Wood I-Joists can be used in place of joists, beams and rafters
True
What are the 3 main types of foundation?
Basement
Crawlspace/pier & beam
Slab-on-grade
Enclosed, accessible space b/w soil and floor of first (ground) floor
Cold climate with deep frost lines
Basement
Accessible space w/ little headroom
Wet climates & areas w/ clay soils
Crawlspace/pier & beam
Structural concrete slab poured on grade (ground level)
Good in area w/ high water table
Slab-on-grade
True or False:
Basements are particularly suitable for climates with high water tables but not locations with deep frost lines
False
True or False:
Slab-on grade is good in areas with high water table
True
Which foundation type is good for wet climates and areas with clay soils?
Crawlspace/pier and beam
True or False:
Residential basement foundations are NOT suited for wet climates with high water tables
True
What is the main type of foundation in NZ?
Pier and Beam
What are the different types of pier and beam?
Ordinary, braced, and anchor
What does CMU stand for?
Concrete Masonry Units
To prevent wetting and eventual rot, it is important to place “__ __ __” between a foundation wall and the timber bearers.
(hint: answer is an acronym made up of three letters)
DPC (damp-proof course)
- a vapour barrier preventing moisture from passing from one material to another
When a wooden bearer is supported by a concrete foundation wall, a “__” is req’d between to stop moisture from passing
DPC, damp-proof course, damp proof course
True or False:
When framing an opening in a floor, double headers are supported by double trimmers.
True
True or False:
Double headers are placed at mid-span to maintain joists’ orientation and depth
False
What is the standard joist spacing?
450mm
_______ are vertical, regularly spaced elements in timber wall framing.
Studs
The short studs located above an opening which supports the portion of top plate over the header are called:
Cripples
The rule of thumb regarding the framing of floor overhangs is:
2/3 normally supported, 1/3 overhanging
True or False:
Bridging is placed at mid-span to maintain joists’ orientation and depth
True
What are the most common roof shapes?
Gable
Hip
When a gable or hip roof structure expresses the roof shape on the interior and does NOT feature ceiling joists, a “ridge ______” is necessary since there are no joists to resist outward thrust.
beam
Rake overhangs feature _____________, which span from the last common rafter to the exterior stud wall and support the fly rafter, or outrigger.
lookouts
True or False:
Lookouts span from the last common rafter to the exterior stud wall and support the fly rafter
True
Where are fly rafters located?
The fly rafter is attached to the end of the lookouts
Purlins
Continuous boards running perpendicular to rafters
A ___________ is the notch in a rafter that is shaped to fit over the external wall’s top plate.
birdsmouth
True or False:
A birdsmouth is the notch made in a rafter to fit over the outside wall’s top plate
True
True or False:
When a timber roof is braced using plywood sheathing, purlins can be slightly reduced in size
False
