I - 4 exterior finishes Flashcards
Building envelope
to protect building components from moisture damage, moisture can be liquid, vapour or solid state.
Exterior envelope three elements
sheathing membrane
capillary break
and exterior cladding
first and second plane of protection
First plane: exterior cladding (siding)
Second plane: building wrap (tyveck)
Capillary break
allows drainage for any water that makes it past first layer of protection and protects from pressure wicking of water. knows as rainscreen 10mm gap between building wrap and cladding.
when is rainscreen rquired?
in we climates where rain is prominent for most of the year.
Rainscreen
maintaining an effective capillary break cavity behind the exterior finish is the most important component of the rainscreen. creating space from strapping the building is good for drainage and allows siding to be placed on building.
Good practice to use pressure treated strapping.
Non moisture susceptible open mesh
large mats that can be used instead of strapping. these are fastened over the sheathing membrane.
must allow for drainage at bottom.
Drainage cavity compartments
purpose of the drainage space is to equalize pressure differentials caused by wind.
drainage spaces should be constructed with compartments that allow the pressure to equalize.
should not continue around corners or extent more then one story
Moisture barrier
consists of building paper, house wrap and peel and stick. BCBC calls is sheathing membrane and works as second plane protection. it intercepts all rain and moisture that makes it past cladding.
Sheathing paper
one or two layers depending on warranty lapped over one another and horizontal lines are lapped 4”
House wrap
comes in large rolls and will cover large ares. joints are to be sealed with tape to create continuous moisture barrier.
self-adhesive membrane (SAM)
(Peel and stick) applied where moisture leaks are anticipated. installed around base of windows and doors and base of walls.
Ridged insulation board
may be used instead of sheathing paper. all joints must be sealed tongue and groove or taped.
Liquid applied barriers (LABS)
(LABS) rolled or sprayed or trowweled on depending on product. create very small membrane on wall that is very durable. 100% water proof.
EIFS
exterior insulated finish system
Wood products for siding
Boards, sheets, shakes and shingles. western red cedar is main species used for exterior cladding.
heartwood is most commonly used. temperature can fluctuate causing 1/4” dimensional change.
DIfference between shakes and shingles
shingles are thinner.
shingles are 1/4-1/5” and shakes are thinker and can be split resawn or tapered.
Split shakes
generally last longer then shingles because the split surfaces resist weather more. nor normally used because finished surface is rough
resawn shakes
is a thick shake that is taper sawn into two shakes. each shake will have a split surface and a smooth sawn surface.
Taper sawn shakes
resembles a large shingle with both faces sawn instead of being split.
Cedar shakes No.1
are best grade of shingles that can be used for roofs and sidewalls 100% heartwood 100% clear and 100% edge grain BLUE LABLE
Cedar shakes No. 2
meet BCBC for roofing and sidewall. shingles tend to warp and twist. limited to sapwood and are RED LABLE
Cedar shakes No. 3
only aloud to use for sidewall. Black lable
Machine grooved shakes and shingles
made from number 1 cedar shingles have machine grooved to give shake look. kiln dried and have two edges cut parallel.