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.
Lapped siding
develed siding is made from taper cut boards. they are installed horizontally and lapped to shed water. must over lapp by 1”.
Board and Batten
type os siding that can only be used vertically. usually used with rough sawn lumber. full 1x8 or 1x10 and battens are usually 2” wide (cottage siding)
channel siding (TNG)
can be used vertically or horizontally. overlap is 1/2”.
Drawbacks of lumber siding
- obtaining quality lumber is difficult and expensive
- wood siding requires maintenance (paint or stain)
- if low quality wood is used knots may call out or wood will split
- takes longer to install
- more prone to rot
Panel-type wood siding
sheets of plywood, heardboard, or OSB and wafer board can be used as exterior finishes. face of plywood has shallow grooves to at 8” to resemble vertical boards. joints in panels and nailing can be hidden by grooves.
Vinyl and aluminum siding
popular because cheep and easy. it produces a capillary break at the bottom of each sheet that have small drainage holes.
vinyl comes is 12 foot sheets. and can change 5/8 depending on season *never butt up to trim or mouldings. must be hung on nails.
stucco
two different types of stucco
- synthetic (acrylic) stucco
- cement stucco
Synthetic stucco (acrylic)
mix of glues , fibres and acrylics applied in two coats. overall thickness is much less then cement stucco.
used to finish EIFS and used largely on commercial construction.
Cement stucco
made from sand cement and lime and water and applies in three coats
provides hards dense water resistance finish. must be minimum of 3/8 thick.
Stucco wire
installed over sheathing. wire has bumps (self furring devices) that space wire away from wall.
expanded metal lath
is made from sheets of steel that have been punched with slits. the sheets are pulled or expanded from a dense surface of fine holes. expanded metal lath is used for extra reinforcement at corners and overhead situations. stucco sticks to this way better then wire mesh
Stucco mixes.
cement stucco is made from sand cement, lime and water. sand must be clean. lime is used to make solution workable and help stick to overhead surfaces.
Proportions of stucco
1 part portland cement
1/4 part lime
3 1/2 parts sand
this will give strong stucco mix add water to make workable only.
application of stucco
- the scratch coat made with plain washed sand and grey in color. scratching with a broom or rake roughens up surface min 6mm thick
- second coat called brown coat. 10% more lime and sand then first coat. used to level surface of wall min 6mm thick
- white sand colouring. finish texture coat provides look for stucco Min 3mm thick
Brick veneer
Veneer is a thin layer of material on top of another material. veneer plywood has thin layers of wood placed one on top of the other. brick veneer construction id s thin layer of brick over other construction.
how big is space supposed to be behind brick vaneer to allow moisture to evaporate.
25mm
cultured stone
is a concrete product that looks like real stone but is only a quarter the thickness. wall sheathing is protected with two layers of a waterproof barrier, and then metal lath is applied. cultured stone is then fixed to lath with mortar.
Sheet metal finishes
ribbed or crimped metal panels. finished with bake enamel or vinyl plastic. aluminum, copper and stainless steel siding materials are available but not often used.
fibre cement siding
made from combo of sand cement and cellulose fibre.
durable, fire resistant and requires little maintenance. james hardie was first manufacturer.
asphalt shingle siding
BCBC allows the use of these to be used as siding. same shingle used for roofs.
overcladding
process used to modernize older high rise buildings. many older high-risers, are not energy efficient and overcladding often uses metal panellized metal that adds insulation.
Exterior casings
doors and windows trimmed with exterior casings. helps seal the connection between exterior finish and window or door.
water table
overlapping the trim materials is very important to prevent rain water from entering the building. water table is used at the base of a wall to make a horizontal join to the foundation or accent board.
Drip cap
same shape as water table moulding BUT its used over doors and windows to form sloping edge to deflect rainwater away from building. metal flashing often replaces drip cap
Flashing
required over exposed openings in exterior walls and horizontal joints in the finish materials that are not overlapped by 25mm
may not need flashing over windows and doors that are protected by roof protection.
how far must flashing extend up wall
minimum 2 “
need flashing ontop of window or door if…
- if distance from underside of soffit to window is more then 1/4th of the projection then it needs flashing.
EX: projection is 24”. distance from the underside of soffit to the window is 8 1/2” flashing must be installed because 1/4th of 24 is 6” and 8.5” is greater then 6
Screened vents
used in wooden soffit
Vinyl trim starter strip
used to attach bottom of the first siding board to wall
under sill (vinyl trim)
used to finish off cut edges of the vinyl siding at the underside of windows or soffits
J trim (vinyl trim)
used to finish sides and tops of openings
Lag screws
used n sheet metal siding. fitted with neoprene washers to make water tight.
nails
must be resistant to rusting. galvanized aluminum or stainless steel nailed are used for exterior work.
galvanized nails
hot dipped, designed for exterior use are resistant to rust and corrosion. strong holding power
electroplated nails
designed for use where not exposed to weather, the electro plated nail also resists corrosion and rust. not as strong holding power
aluminum nails
aluminum nails are used to attach aluminum soffit, fascia and trim pieces. corrosion will occur ing galvanized material touch aluminum finishes.
Common nail
main type of nail used in framing.
box nail
is similar to a common nail but with thinner shank. hot dipped galvanized box nails are used for attaching wood finishes trim and siding.
casing nail
has small head that is harder to see. used to attach wood finishing trim.
siding nail
used to attach wood siding and finish trim pieces. head is domed to allow it to sit flush with wood so you don’t have to use a punch
roofing nail
used to
- fasten vinyl siding to sheathing
- instal panel-type insulating sheathing
- apply sheathing paper
- instal stucco wire and metal lath
when used for installing with siding. big head allows for movement with temperature changes.
waterproof nails
waterproof nails are threaded shank with neoprene washer behind the head so its water tight.
staples
used to attach vapour barriers to wood
sheathing paper installation
apply in sheathing like manner overlapping joints by at least 4”
use roofing nails if it is super windy
only let house wrap exposed for max 120 days
exterior sealants (caulking)
required at joints between masonry, siding, stucco, and door and window trims.
must be able to stretch because most building materials expand and shrink with temperature change.
acrylic caulking
used in low traffic ares of infrequent wetting.
elastomeric (rubber based caulk
typically used for sealing window flanges to building envelope
Butyl-polyisobutylene caulk
used outside and can be good adhesive for metal glass and concrete and wood
multicomponent (polyurethane) caulk
can be used for precast, tilt-up, concrete, masonry, exterior insulating, metal curtin walls and perimeter joints. very stretchy
Backer rod
backer rod is used to provide a backing for caulking. rod should be installed so it it tight fitting and set back from the surface.
backer rod should be 20% bigger then joint.
may be plastic foam or neoprene.
applying caulking
- clean surface are a where caulking is to be applied.
- mask both sides of joint to provide clean bead.
- some require primer.
- insert backer rod into joints if needed do not push in too far.
- caulk joint that will provide full penetration of caulking.
- use finger or tool so sooth out caulking
- remove tape while its wet
Calculating for exterior finishes
determining square feet or meters needed
subtracting window areas
calculating coverage of product being used
allowing for waste.
maximum exposure for given siding
found by subtracting th required overlap from the actual width of board.
ex: 1x8 siding has width of 7 1/4” which mean max exposure of 6 1/4”. so 8 / 6.25 = 1.28
board and batten calculations
even though 8” board is 7 1/4, it still is 8 “ because they need to be spaced get wall height and length and find best suited length of board
Wood panel cladding calculations
typically 48” by 104” no reductions are made for windows when calculating.
sheet metal panel cladding
sheet metal roofing panels are also used for siding. custom order length based on area needed to side
vinyl and aluminum siding
sold by coverage area. allow for 5% waste.
fibre cement siding
calculated the same as wood beveled based on exposure
stucco cladding
follow manufactures methods for estimating amounts
brick vaneer cladding
use bricks dimensions plus mortar thickness to calculate space taken up on wall. red brick is 3/8 mortar it takes 6.3 bricks to cover 1 square foot. so 630 to cover 100 square feet.
cedar shakes and wood shingles (install)
shingles are blind nailed. nailed with two nails placed three quarters of an inch from the sides and 1 “ above the butt of the next shingle. galvanized hot dipped nails are used.
exposure for shake or shingle sidewall applications
16” single course : 7.5” double course: 12”
18” 8.5” 14”
24” 11.5” 16”
Lumber siding nailing
nailed in place with either dome head siding nail or casing nails. but be galvanized or hot dipped.
exposure of lumber siding
max exposure found by subtracting required overlap by the width of actual board. ex 1x8 bevel siding has actual width of 7.25 therefor max exposure is 7.25 - 1 = 6.25
Bevel siding exposure
the exposure for each course of siding is calculated so that the last board will have same amount of exposure.
measure vertical distance from soffit to level line. divide this height by max exposure to determine number of courses. then divide this number by distance from level line to soffet. ex
112.75” is to be covered with 1x10 bevel siding.
max exposure is 9.25-1= 8.25
number of courses is 112.75 / 8.25 = 13.67 or 14
112.75 / 14 = 8.05
starter strip
the first board of bevel siding is tipped out from building by the same amount as the board above it. place two ob wall and measure distance from wall to shingle.
chalk line
chalk line at top of every third course.
scarf joint
used to join lumber siding. should be made over vertical supports as long as ply behind it is .5” thick. then caulked with sealant
corners horizontal bevel siding
are mitred or covered with battens. corners of siding are butted into each other.
sometimes vertical corner posts are installed for better water seal
water table and vertical wood siding
water table is set with builders level and flashing over water table must extend up under sheathing paper at least 2” ends of wood ends should be beveled and back primed.
Wood panel siding installation and windows.
windows are often installed when wall is paying on subfloor. flashing and sheathing paper are applied over wall studs and the paneling is fitted around the window and door openings. windows are caulked and then cased and wall is stood WITH JACKS because its very heavy.
Basic installation rules for vinyl siding
- cant be cross cut with a miter saw or skill saw install blade backwards
- use a cutting jig
- install siding 6mm or 12mm c(in cold) to flashing and J’s
- always put screws and nails in middle of slot provided
- use nails with minimum 8mm head and 20mm hank
- don’t drive nails fully home
- caulk all necessary areas
Prep for vinyl siding
- install J and corner pieces first.
- determine where first course of siding will start chalk line
- install inside and outside corner posts plumb (extend past starter strip 3/4” then 1/4” left between posts and soffit
- over lap vertical pieces of corners by 3/4” allowing water to flow over
- nail starter strips between corner posts butted n with a gap of 6mm and hanging over foundation by 12mm
- place J trim around all doors and windows. extending 25mm past top and bottom of al frames.
-**horizontal trims are cut 25mm longer to fold over vertical trims - place undersil trim below all openings so that it extends as far as J
- install fur out strip at top of undersil to preserve the same angle
- caulk where j and sill trim meet
- install wall panels nail every 200mm (windy) or 400mm not windy
- ## overlap panels by half factory notch, do not nail 150mm close to ends
Aluminum siding
- corners can be finishes with corner posts or corner caps. caps give look like siding has been miter beveled.
- must be kept 12-20mm back to allow for corner cap
Framing shrinkage and aluminium siding
sometimes shrinkage in floor systems can make siding bulge and unhinge prolock. use engineered flooring system to prevent this.
cutting aluminum siding
use skill saw and install blade backwards.
Sheet metal siding
- easy an fast to install
- fastened to studs or strapping with screws with neoprene washer.
Fibre cement siding
- store in dry area before installation
- when cutting boards, coat cut with primer
- wear mask because cutting silica dust is bad for lungs
- ## use 7 1/4 skillsaw with polycrystalline diamond tipped blade to cut.
nibbler and power shears
these reduce dust when cutting fibre cement boards.
nibbler cuts narrow grove in board and shears slice it n half
Holes in cement fibre siding
cut holes for electrical outlets using a jigsaw equipped with diamond tipped blade. use drill bit or hammer and nail to make starting hole.
Nails and fasteners for Cement fibre siding
- should be double hot dipped galvanized or stainless steel. should be face nailed or blind nailed, never angle nailed
- use pneumatic fastening siding or roofing nailer. pressure at 80-85 psi.
- when face nailing, use 2” siding nails.
- when blind nailing use nails with 3/8 diameter head as close to exposure line as possible.
Calculating exposure of cement fibre board.
- measure total height plus 2” for foundation
- determine max exposure by subrtacting 1 1/4” from width of siding
- find the number of courses by dividing total height by max exposure
- then to find exposure divide course by total height.
ex: find exposure for boards 8 1/4” on wall that is 98 1/2”
8. 25 - 1.25 = 7
- 5 + 2 (foundation) = 100.5
- 5 / 7 = 14.35 (15)
100.5 / 15 = 6.7 OR 6 11/16ths
Corners for horizontal cement board
usually covered with battens or corner boards. leave 1/8th gap for caulking
flashings cement fibre board
should be flashed with metal or suitable fibre cement materials. flashing should extend 3” on both sides of the joint and 2” above.
Caulking fibre board siding
- caulking must be compatible with siding and should be paintable
- exterior acrylic or urethane are normally used
- used when cement siding intercepts with different material (wood, metal, windows, doors, vents etc…)
- do not caulk when drainage is expected
Painting fibre boards cement siding
- do not paint back of siding so it can breath
- ## use only latex based paint
Exterior insulation finish systems application
- good for climates where its very wet when used with drainage rainscreen
- expanded polystyrene board is applied to the wall surfaces using adhesives or/special fasteners for holding foam insulation.
- fibre glass mesh is applied over insulation to provide reinforcement of the stucco.
- thin finish texture coat of stucco is coloured and applied in a thin layer over the base coat
Cement stucco
- provides a hard, dense water-resistant cat of cemented material at least 15mm thick over exterior sheathing. stucco is applied in three layers over metal lath or stucco wire.
- metal lath is used for horizontal surfaces ,existing concrete walls and sometimes corners
- stucco wire is used for vertical surfaces and must be installed with the self furring devices against wall sheathing
- nailing metal lath or wire should be 6 or 4 “ vertically and 16 or 24 “ horizontally
- ## must be overlapped by 2” snd staggered like sheathing
Expansion and control joints for stucco
- will expand and contract with temperature change
- control joints are placed every 12 feet
- expansion joints are placed at each floor level to allow for shrinkage and settling of building.
Stucco and window and door flashings
- weight of stucco will apply loads onto flashing over windows and doors. flashing must be kept clean from windows and doors by 3/8ths to allow for this deflection
- aluminum will react with stucco and should not be used.
Stucco mixes
- mixture of portland cement, lime, aggregates and water
coat 1. Basecoat (grey) used with portland cement ot make first layre
coat 2. (brown coat) has 10% more like and sand to make weaker so it wont crack
coat 3. finish coat made of white cement like and white sand with % pigment
application of stucco
- base coat must be 1/4 “ thick measured from face of lath
- the second coat must also be 1/4” think
- the finish coat may be as thin as 1/8” to make the overall thickness of stucco 5/8ths
Stone dash
the finish coat is obtained by small coating of small rocks. applied using a scoop to throw pebbles at wall.
Brick veneer
- bricks that are applied in a think layer. this layer is usually 2-4” thick. can be 8” sometimes
- supported by making width of foundation bigger** or to bolt steel ledger to foundation wall to lay bricks ontop of
Lintles (brick siding)
metal angle iron supports are used to span over openings. minimum end bearing is 3.5”
Brick ties
metal brick ties are used to fasten veneer wall to wood framing.
- 24” studs vertical spacing of 500mm
- for 16” studs vertical spacing of 600mm
Shrinkage and brick veneer
brick veneer will not shrink. but wood frame construction will. gap should be left at top of veneer to allow building to settle. gap should be 3//8 for every floor of masonry construction.
flashing in masonry siding
flashing at base of veneer siding must extend behind building paper at least 6”.
weep holes
provided to allow any water that gets behind veneer to escape. must be spaced 32” apart and be clear of mortar
Wood trim finish material
- smooth lumber (s4s) and rough sawn lumber (s1s2e) can be used for finishing trim.
- comb face lumber is lumber that has gone through plainer with serrated blades to leave grooves. holds paint better and hides nails.
- typically nailed with galvanized casing nails no more then 24 “ on centre
Fibre cement trim
- applied similar to wood trim
- some trims have rabbeted edges for lapping siding pieces
fascia systems
most engineered wood a fibre fascia requires drip edge to keep water from building up behind the fascia board.
metal and vinyl fascia systems
prefab metal ad vinyl fascia systems are popular in new construction builds, fits right over facia and snaps into channels.
Installing metal and vinyl fascia systems
- install undersil trim along top of rough wooden fascia
- cut fascia material to width and punch ear hangs on top.
- hook the bottom edge over the bottom of the rough fascia or over j channel
Wooden fascia
smooth lumber (S4S) , rough sawn lumber or resawn lumber (S1S2E) can be used for finishing fascia
- roofing material must project over this, for this reason fascia is done first.
- instal : nailed with galvanized casing nails. double row of nails 24” oc
fibre cement fascia
Applied the same as wood fascia but consult manufactures installation practices
Metal and vinyl soffit installation
- nail all trims at 12” oc.
- to allow for expansion notch j trim by 3/4”
- ## nail ledger to side of wall to support j channel
Wood soffit installation
- channel siding or plywood is sometimes used
- strip at back is allowed for venting
- can be applied horizontal to lookouts OR at angle underside of rafter tail.
Fibre cement soffit
- typically 1/4” thick
- should be supported in both directions and no further apart then 24 oc
- PVC caps or battens cover joints
Continuous ventilation
BCBC requires roof spaces to be vented when there is insulation between the ceiling and the underside of the roof sheathing.
- installing vented soffits is the easiest way to achieve continuous ventilation.
two types of gutter systems
Attached gutters : attached to house
hidden gutters: framed into the eves of the roof and made water tight
Rainwater leader
- gutters grain into vertical pipes called rain water leaders. installed to carry water from roof to storm building drain.
leaders at foundation level (storm building drains
sloped horizontal pipes at foundation level called storm building drains
- drains to drywall or storm sewer.
Metal gutters
either galvanized steel or aluminum. coated with baked enamel.
- width of gutter measured horizontally from fascia to the outside of the gutter.
Installation of metal gutters
attache to finish fascia or rafter tails using hangers. gutters should slop downward towards leaders. (1/16 per half foot)
- * snow sliding can rip gutter off roofs, place gutters well below edge so that snow will flow over them
continuous gutters
- used in most new construction
- manufactured on site
- overall length of run is measured then piece is cut
all holes and laps sealed with caulking
Vinyl gutters
- installed like metal gutters
- easy to use
-low maintenance - ## joints are sealed with fast setting cement
hidden gutters
- is done as part of roof framing
- trough is made at the edge of roof and sealed with roofing membrane
- framing this trough is done by attaching wide fascia board to the rafter tails at right angle that extends above roof.
- if leaks occur serious roof problems can occur.
Downspouts (leaders)
- must match material used for gutters
- ## using elbows to connect downspouts to the side of wall thenr un down the side of wall
scuppers
flat and low sloped roofs are normally trimmed along their perimeter with a curb (parapet). small openings are made in the curb and a rectangular rain water collecting box is placed in these areas to drain rainwater down a leader.
roof drains
flat roofs can have drains that run water though interior portions of buildings. interior leaders must be constructed by a plumber
Storm sewer
is a storm sewer is available connect rainwater leader to it downstream from buildings perimeter drain.
- * do not run rainwater leaders into perimeter drain
dry well
drywell is only suitable if ground is well-draining. it consists od large perforated concrete or plastic tank inside a 4’ by 6’ hole filled with drainrock
- natural groundwater must be below bottom of drywell
- covered with filter cloth and backfill
- located 5m from building
splash blocks
in low rain climates, water is let to run onto surface of ground away from foundation. splash blocks direct water away from building perimeter.
