1. Final Project - Materials - Moisture Protection and Thermal Insulation Flashcards
Admixtures
mixtures added to conrete mix to make it water repellent
- materials such as salts of fatty acids, mineral oil, and powdered iron
- reduce strength of concrete, but make it less permeable to water
bituminous coatings
asphalt or coal-tar pitch materials applied to the exterior side of the foundation wall
-brushed or sprayed on, not in cold
cementitous coatings
- portland cement mortar troweled on masonry or concrete foundation walls
- mortar coatings are used on rough surfaces to make them smooth
membrane
- built up layers of hot or cold applied asphalt felts or membranes of butyl, polyvinyl chloride, and other synthetic materials
- usually used for waterproofing walls subject to hydrostatic pressure
plastics
made of silicone and polyurethane coatings
-reserved for above grade damping
dampproofing
control of moisture that is not under hydrostatic pressure
waterproofing
control of moisture under hydrostatic pressure
bentonite panels
flat packages of bentonite panels inside kraft paper packages
- placed under slabs and against walls
- after backfilling the clay expands in the presence of moisture to form a waterproof barrier
When describing size, estimating, and ordering materials, roofing area area is referred to in …
… squares. A square is equal to 100 square feet
Shingle Exposure
shingles are laid so that only a certain portion of each shingle is visible: this is caled exposure
- this dimension varies with the pitch of the roof
- 30 lbm asphalt felt is used as an underlayment
Slate tile
- made by splitting quarried slate into rectangular pieces from 6 in to 14 in wide and from 16 in to 24 in long
- about 1/4” thick
- laid over 30 lbs asphalt roofing felt
- very expensive but very durble and fire resitant ; can last over 100 years
Clay tile
similar to slate tile in roof buildup
-also expensive bu durable and fire resistant
concrete tile roofing
less expensive than clay tile
also very durable and fire resistant
metal roofing
- materials include copper, galvinazed iron, aluminum, and terneplatem stainless steel
- durable, attractive, can conform to a wide varaity of roof shapes
- high cost and difficult to install properly due to a high coefficient of expansion
- joints must be designed to account for expansion and contraction
- installed over asphalt roofing felt laid on top of wood or nailable concrete decking; exception to underlayment is for terne or tin roofs, which require a rosin-sized paper because asphalt can react with the tin
terneplate
steel sheet coated with lead and tin
minimum slope for metal roof
3:12
Name roof components
Horizontally applied board sidings
• In Europe, siding is nailed to vertical wood spacers (1x3’s) that are aligned over
the studs…called a rainscreen and creates a pressure equalization chamber
behind the siding that acts to prevent water penetration in a wind drive rain
- In the US, boards are nailed tightly over the wall sheathing and housewrap
- Allows for installation over insulating sheathing materials without requiring a nail based sheathing
preformed roof panels
- shaped pieces of metal or assemblies of metal with insulation between that are self supporting at intermediate supports
- roof panels span purlins, and wall panels span horizontal girts
- corrugated or fluted sheets
- made from aluminum, galvanized steel, and porcelain enamel steel
- most economical when used on large, flat, unbroken expanses of walls and roofs
Membrane roofing
- includes materials applied in thin sheets to nearly flat roofs
- includes liquid applied products that can be applied to any roof slope
built up bituminous roofing
- consists of several overlapping layers of bituminous saturated roofing felts cemented together with roofing cement
- bituminous material can be either asphalt or coal pitch tar
built up roof can be installed over nailable and non-nailable decks
for nailable deck: a base sheet of unsaturated felt is nailed to the deck and covered with a coating of roofing cement
on non-nailable decks: base sheet is omitted and a base coat is applied
- three, four, or five layers of sturated roofing felts are then laid on top of each other, each layer bedded in roofing cement so that felt does not touch felt
- a final coating of bituninous coating is placeed over entire roof and covered with gravel
- gravel protects the roof from sunlight and other effects of weathering
inverted membrane roof
- built up roof is placed on the structural decking and rigid, closed cell insulation is placed over the roof rather than under it
- insulation is held down with gravel ballast
- purpose of this type of construction is to protect the membrane from the normal deleterious effects of expansion and contraction, drying ultraviolet rays, and foot traffic than can cause leaks
cricket
saddle shaped projection on a sloping roof used to divert water around an obstacle
scuppers
- also called overflow drains
- built through parapet, positioned with their low edge slightly above the top of the roof to provide a second means of drainage should the primary drains become clogged
single ply roofing
-a single membrane layer of various types of materials
EPDM
ethylene propylene diene monomer
- only available in black
- must be sealed with adhesive or pressure sensitive tape
CSPE
chlorosulfonated polyethylene
- also known as Hypalon
- available in black and white
PVC
polyvinyl chloride
- relatively inexpensive
- seams are heat welded
- available in white
TPO
thermoplastic polyolefin
which can be recycled and reused for roofing: thermoplastics or thermoset plastics
thermoplastics only
Liquid applied roofing
- includes butyl, neoprene, hypalon
- also used for below grade waterproofing on foundation walls, tanks, and pools
- well suited for complex roofs such as thin-shell conrete domes
roof expansion joints
- required in buildings to allow for roof movement caused by temperature changes in materials and differential movement between builing sections
- located evey 100 ft in long buildings
- located at the junciotns of T, L, and U shaped buildings
A building with a basement is being design in a wet climate. Which of the following water control materials/method would an architect recommend?
cementitious coatings
geotextiles
french drains
sloping soils away from the building
geotextiles
french drains
sloping soils away from the building
cementitious coatings are only used for dampproofing
geotextiles
Geotextiles are permeable fabrics which, when used in association with soil, have the ability to separate, filter, reinforce, protect, or drain.
Typically made from polypropylene or polyester.
the minimum suggested pitch for a normal slope asphalt composition shingle roof is
4:12
in order for a asphalt or composition shingle roof to have a 2:12 slope, what must me built into the roofing
a double layer of roofing felt is required
-most manufactureres don’t recommend this slope
What is used to keep water from penetrating an expansion joint at the intersection of a roof and wall?
counterflashing
a minimum diameter for a weep hole in a masonry wall is
1/4 in
normal slope asphalt or fiberglass shingles are to be isntalled on roofs with a mininmum pitch of
4:12
advantages of unventilated roofing
- simplicity of detailing, low roof profile , no risk of wind blown water into the roof assembly
sodium bentonite
a naturally occuring highly expansive clay
-used for bentonite waterproofing
blind side waterproofing
used where there is no working space between a sheeted excavation and the outside of the foundation wall
Longterm Thermal Resistance (LTTR)
thermal resistance value of a closed cell foam insulation product measured after storage for five years under prescribed laboratory conditions
Loose fill
- Glass wool/ rock wool
- all loose fill require vapor barrier or vapor retarder
- Fill is blown onto attic floors and into wall cavities through holes drilled in siding
- Good for retrofit insulation in older building, may settle in walls
cellulose insulation
shredded wastepaper or wood fibers
- contains 75% recycled matrials
- combustible but chemicals are added to make it fire resistant
fiberglass loose fill
insulation is made by spinning molten glass into fibers
-contains 20-30% recycled materials
vermiculite
- hydrated laminar magnesium aluminum ironsilicate
- may contain asbestos
Batt or Blanket
- Glass wool/ rock wool
- Between framing members and held in place by friction or facing stapled to framing
Rigid Board
Polystyrene Foam Boards are applied over wall framing members either as sheathing on the exterior or as a layer beneath the interior finish material
High R value, can be used in contact with the earth, moderate cost
Foamed in place
Polyurethane
Foam is mixed from two components and sprayed or injected into place where it adheres
High R value, high cost, good for structures that are hard to conventionally insulate; conforms to shape of cavity; seals all cracks
reflective insulation
when a radiant barrier is combined with a backing of insulation
where should a radiant barrier be placed to block heat gain?
to block heat gain, a radiant barrier is placed on the outside of conventional thermal insulation, such as on top of attic insulation
-heat radiated from the hot roof deck is reflected back toward the roof, reducing the heat that would normally strike the top of the thermal inslation
refective surfaces have two properties that make them good for insulation
-reflectivity: measure of how much radiant heat heat is reflected by the material; measure between 0-1; material with a reflectivity of 0.8 means that 80% of the radiant energy striking the material is reflected
–emissivity: measure of how much energy is emitted; energy given off as a result of surface temperature
to be effective radiant barrier must have a minimum reflectivity of ___ and emissivity of ___
reflectivity - 0.9
emissivity - 0.1
insulated concrete form (ICF)
- interlocking foam insulation blocks or panels that serve as forms for pouring concrete walls
- ICF remain in place while concrete cures
- serves as backing for gypsum board
- foam used is usually expanded polystyrene (XEPS)
Thermoset Plastics vs thermoplastics
thermoset plastics: permanently harden when they are subjected to heat and then cured;
they permanently lose their shape if heated again; EPDM, CSPE
thermoplastics:can be repeatedly softened with heat and then harden again when cooled; PVC, TPO
polyisocyanurate
rigid, closed cell, continuous foam board insulation for roofs
R5.7 / in
Whic of the following materials provides the highest insulation value (R value)?
a. expanded perlite
b. expanded polystyrene
c. fiberglass
d. polyisocyanurate
d. polyisocyanurate
expanded perlite: R2.7
expanded polystyrene: R3.75
fiberglass: 3.1
polyisocyanurate: R5.7
Which of the following would be LEAST apporpriate for insulating a steel stud wall
a. polystyrene boards
b. rock wool
c. fiberglass batts
d. perlite boards
b rockwool
rock wool is a loose insulation poured or blown into cavities
-usually not used in commercial constuction
the average R-value per in of fiberglass unsulation is ….
3.3
which of the following strategies will NOT prevent ice dams?
a. provide ridge and soffit vents
b. place batt insul between the roof rafters
c. seal and insulate ductwork in the attic space
d. caulk all penetrations from below, such as electrical conduit or vent stacks
b. place batt insul between the roof rafters
- the warmth of attic spaces heats up the roof and causes the snow that has accumulated on the roof to melt.
- the eaves are not as warm as the rest of the roof so as melted snow runs down the roof, it refreezes as it reaches the colder eaves
- the best strategy is to keep the attic as cold as possible
- ridge and soffit vents allow cold air to flow through attic
- insulation between rafter will make ice daming worse, instead insul should be placed on the floor of attic
Describe relationship R value to U value
R = total thermal resistance of assembly = F/Btu/hr x sf
U = thermal transmittance of a building component
U=1/R
Imperial U = 5.678 x Metric U
Which types of insulation are fire-resistant, and which are flammable?
Which are moisture-resistant / contact with earth?
Fire-resistant: cellular glass (rigid) insulation, fiberglass batt insulation
Flammable: foamed plastic (rigid) or foamed in place polyurethane *need to be protected from interior
Moisture-resistant: rigid insulation with closed-cell structures - extruded polystyrene, cellular glass
sealants are classfied as…
low: used in joints with +-5% movement
intermediate: +- 12.5% movement
high: +- 25% movement
- type used depends on expected joint movement
- width and depth of a selant are critical; width is determenined by expected joint movement; depth is equal to width of joint
- example for joints 1/2 in to 1 in thick, the depth should be 1/2 in
exterior insulation and finish system (EIFS)
caldding assembly consisting of a wet applied cementitious finish over a rigid insulatoin board that is attached to building sheathing
3 classifications of EIFS:
polymer based (class PB): use expanded polystyrene insulation with the base coat applied direectly to the insulation w/ embedded fiberglass mesh
polymer modified (class PM): used extruded polystyrene that is mechanically fastened to the building sheathing and strcuture along w/ reinforcing mesh
mineral based (class MB): uses portland cement stucco in traditional manner
waterstop
a preformed piece of material used to seal construction joints
which of the folliwng is the best sealant to use between exterior, precast concrete wall panels
polyurethane
Either one part or two part provides excellent resistance to weather and is capable of 25% to 50% movement
- can span wide joints typical of precast concrete
- available in colors
- can be painted
Acrylics are unsuitable sealants for wide joints because…
…of its limited potential for joint movement and their inability to fill the large width joints that are typical of precast conrete
disadvantage os butyl selants
limited joint movement and because they are only available in darker colors
-generally used for areas underwater
disadvantages of latex sealants…
-limited joint movement
typically used for joints with no expected movements, such as those around door and window frames
asphalt imregnated building paper is used under siding primarily to
- increase water resistance of the wall
- also serves to prevent air infilitration
Which of the following would be most apporpriate for dampproofing an above grade concrete wall with a moderately rough surface
a. cementitious coating
d. bituminous coating
c. synthetic rubber
d. silicone coating
d. silicone coating
it can be sprayed , painted, or rolled on
if the wall was below grade, a cementitious or bituminous coating would be apporpriate
perm rating
is the measurements of how much moisture passes through a certain material in a given amount of time
vapor retarder are selected based on …
their perm ratings
the best vapor retarders have the lowest perm ratings
rate the foloowing materials by their perm ratings (lowest to highest)
10 mil polyetheline
gypsum wall board
1 mil aluminium foil
exterior oil paint
1 mil aluminum foil - 0
polyethelene - 0.03
exterior oil paint (3 coats) - 1.6 - 3.0
gypsum wall baord - 50
most architectural coatings are composed for four basic types of ingredients
-solvents, vehicles, pigments, additives
-advantages of latex paint
-good when used for exterior; breathable, preventing moisture from becoming trapped behind the painted siding;
flexible coating, able to stretch as painted material expands and contracts with temperature changes
enamels
- glossy surface paints; high proportion of vehicle
sealer
-unpigmented liquid that can be thought of as a primer for a clear coating;
it seals that pores in the substrate so that the clear coating will not be absorbed
why are clear coatings not recommended for exterior surfaces
-they are particularly susceptible to UV damage, lasting no more than a year before peeling occurs
most damage caused to paint is a result of what?
- caused by water getting behind the paint film and lifting it off the painted surface;
good construction practices and proper design of air barriers can eliminate damage to paint
Which side of the assembly do you place vapor barrier?
Warm side
How does vapor migrate?
From high to lower pressure areas.
Diffuses from high humidity (inside) to low humidity (outside). *when cold
Why do we need vapor barriers?
If vapor touches cool surface whose temp is below the dew point of the air, it will condense. - deteriorates wall
- vapor retarders stop vapor from getting into the wall
- ventilation allows vapor to escape
How would you prevent condensation on windows?
Condensation = vapor that touches cold surface and turns into water
- raise the surface temp of the glass :
1. warm air supply
2. use double or triple glass
Where do you place vapor retarder on roof and how to mitigate any moisture trapped?
Under the roof insulation.
May require topside vents for ventilation
What is the perm rating required for vapor retarders?
1 perm or less
all seams & joints lapped and taped.
Does air barrier need to be vapor retardant?
NO.
Air barriers must be permeable to allow vapor in the wall to escape.
What is required on top of earth in crawlspace?
Polyethylene film, to retard the migration of ground moisture.
Attic & roof ventilation
Eave vents or vents on the ridge. Net ventilating are 1/300th of the area to be vented, at least 50% along the ridge
Soffit vents to be continuous screened vent
Unheated crawl spaces ventilation?
Openings 1.25 sq.ft. / 25 li.ft.
At least 1 opening on each side, as high as possible and near a corner to promote ventilation
With high and low pressure on either side of a wall, which way is the moisture in air likely to move?
It will always migrate towards the lower air pressure.
Define:
1 - Air Vapour Barrier
2 - Vapour Retarder
3 - Moisture Barrier
1 - Air Vapour Barrier
• material of low permeance
• prevents moist. from entering /condensing
2 - Vapour Retarder
• vapour resistant material of <1 perm
(can apply to gwb!)
• 3 classes (nearly impervious, <1 perm, 1-10 perms)
3 - Moisture Barrier
• typically used below slab to prevent ingress of ground moisture
