Construction Detailing Flashcards
Board feet
Piece of lumber 1 inch thick by 12 inches wide by 12 inches long or 144 inches^3.
A 2x6 that is 12 inches long
A 2x4 that is 18 inches long
Ex. how many board feet is a 1x10, 8’ long?
(1x10x8) / 12 = 6.67 board feet
Ex. 2x6x12’
(2x6x12) / 12 = 12 board feet
EPDM vs PVC single ply fully adhered roof membrane
EPDM weathers well and handles temperature fluctuations. Good for flat roofs with pavers in temperate climate.
Refrigerants that are banned in the US
Halon and chlorofluorocarbons (CFC)
Type of construction to use for 4 story hotel with exposed structure, high fire resistance and fast construction
One way solid slab concrete frame
Low slope roof vs steep roof
2:12 and lower (1/4” per foot min)
Pitch pan
Sheet metal open box that is filled with sealant called pitch. More likely to leak than cone-shaped boot because relying on chemical, not mechanical solution.
Cone-shaped boot
Mechanically diverted and also seal
Cricket
Mini pitched element to mechanically divert water around something (like a chimney)
Topside roof vent
Vents vapor in space between roof membrane and insulation (mushroom shape)
Options for roof insulation location
- Below structure (2 types: ventilated cavity OR closed cell spray foam where it acts as air/vapor barrier)
- Above deck (vapor barrier, rigid insulation, membrane)
- Above deck, insulation over membrane
Ice damming
A home’s escaping heat warms the roof sheathing and melts the underside of the snow layer on the roof. Insulating and ventilating the roof will prevent this.
Hardwood v softwood
Hardwood comes from deciduous trees, which grow slower and tend to be denser. Higher modulus of elasticity, More resistant to wear, more expensive. Also more prone to splitting from hammering a nail (use screw or bolt).
Softwood comes from evergreen trees. More common in structural lumber.
Plainsawn vs quartersawn
Plainsawn cheaper and less durable. All cut in parallel direction across log.
Quartersawn is cut in quarters and then diagonally parallel across log. More dimensionally stable so will be more durable. More visually consistent and finer grain.
Moisture content of wood
MC15 = 15% moisture when delivered to site
Low number is good because it is stronger
S-DRY is shorthand for MC-19
Wood shrinks mostly tangentially and cracks (called checks)
Wood warping
Warps more when cut parallel to grain
Shrinks evenly when cut perpendicular to grain
Glulam
Laminating small pieces together. Length is only limited by transportation to jobsite.
Cross-laminated timber
Alternating strips of timber in perpendicular directions. Can make really strong, large panel and large openings can be cut because it has 2-way support.
Laminated strand lumber (LSL) and oriented strand lumber (OSL)
Shredded wood strands glued and pressed
Least strong and least expensive options
Used as rim boards or short span headers
LSL has longer strands
Parallel strand lumber (PSL)
Shredded wood strands glued and pressed in parallel direction. Stronger than LSL or OSL.
Wood I-Joist
Dimension wood flanges and OSB flange create longer spans
Laminated veneer lumber (LVL)
Layers of veneer laminated together
Used for headers, beams, rim boards
Wood plastic composite
PLastic, wood and chemicals are injection formed. Used otudoors because less likely to shrink, warp and decay.
More flexible than wood so needs more support.
Oriented strand board (OSB)
Strands of wood pressed and glued together. Layers alternate directions of strands. Odd # of layers so exterior faces have same dimensional stability. Used for exterior sheathing.
Particle board
Smaller fibers, used with veneer/laminate on top. Not very strong or moisture resistant.
Fiberboard
Smaller fibers than particleboard so more stiff and able to handle fasteners better. aka Masonite
Low and high density fiber board can be used for sheathing (non-structural)
32/16 rating on plywood means…
Rated for roof construction with supports at 32” O.C. and rated for floor construction with supports at 16” O.C.
Bond classifications for plywood
90% of plywood is Exposure 1 which can be exposed to water but not for long periods of time. Exterior rating is best.
Forest Stewardship Council (FSC)
Certifies wood products. Binders with formaldahyde offgas in OSB and MDF. Can be spec’d with low finish
Treated wood - when is it required and what types can be used where?
Required when wood joists are less than 18” above grade, wood beams/girders are less than 12” above grade, plates,sills or sleepers are in direct contact with masonry or concrete which is touching earth, OR wood framing or sheathing is less than 8” from soil.
ACQ and CPA have copper in them and can’t be used with steel or aluminum fasteners. Stainless steel, copper alloy or zinc galvanized. Hot dipped galvanized can be used above ground.
Micronized Copper and PTI is paintable, can contact ground, is non-corrosive and nontoxic
DOT and SBX are nontoxic and can contact ground. Can be used where termites are a problem.
Phased out for toxicity: Creosote, CCA
Naturally decay resistant wood species
Black locust, red mulberry, osage orange, pacific yew
Slightly less resistant:
Cypress, catalpa, cedar, chestnut, white oak, redwood, black walnut
Naturally termite resistant wood species
Easter red cedar and redwood but only heartwood
Nails
Expensive until recently that’s why complex joinery was used.
Flat heads:
Common nail, sinker nail, box nail, roofing nail
Tiny heads:
Finish nails, casing nails, brads
Deformed shank nail has teeth, used for sheathing, subflooring
Sized in units called pennys (d)
Large = 60d
Small = 2d
Nail coating
Bright nails have no coating
Hot dipped galvanized have highest level of weather resistance
Hot galvanized not as weather resistant
Three types of panelization
Framed panels (arrives with sheathing on one side)
Stressed-skin panels (sheathing on both sides, very strong)
SIP/Structural Insulated Panels (Insulation in between sheathing so no thermal bridging)
Balloon framing
2 story tall studs
Requires fire stopping because the continuous stud cavity is a path for fire
Platform framing
1 story tall studs with platform in between
Allows for tilt up construction
Doesn’t require long lumber (tall trees)
Doesn’t require fire stopping at floors