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Why do we need thermal and moisture protection?
- Protection from weather
- Temperature extremes create expansion and contraction of materials which can lead to cracking and deterioration.
- Excessive heat loss or gain creates human discomfort and increased equipment and energy costs.
- Leaks cause uncomfortable, costly or hazardous water damage.
- Heat loss and gain is a focus for building codes.
- Water: below ground; leak as capillary action or due to hydrostatic pressure.
- Precipitation: fog; drizzle; hail; rain; sleet; snow
- Water Vapor: present in the air as humidity; caused by equipment, activities, human habitation; condensation of the vapor collects on interior surfaces
The ability of liquid to flow in narrow spaces without the assistance of external forces such as gravity. (porous absorption, ink and paper or a paint brush)
Consists of surface accumulations of water, caused by rain, thawing ice or snow.
- Water contained in the voids and crevices under the earth's surface.
- Flows very slowly through aquifer (permeable material)
- Control or diversion from buildings.
GROUND WATER TABLE
- Level below which the earth is saturated with water.
- Determined by test borings.
Ground Water Control
- In order of watertightness (least to greatest)
- Permeable: capable of being penetrated by water without causing rupture or displacement
- Pervious: permitting leakage or flow of water through cracks, leaks, or openings
- Water-resistant: having no openings larger than capillary pores that permit leakage of water
- Water-repellent: incapable of transmitting water by capillary action, but able to transmit water under pressure
- Waterproof: completely impervious to water, whether under pressure or not.
- Materials and methods that prevent moisture from penetrating a building at or below grade.
- Cannot resist constant hydrostatic pressure.
- Applied by brushing or spraying a liquid form on foundation or basement walls that make contact with the earth.
- Asphalt base coating: 2 coats
- Cement plaster: densely mixed and troweled or pneumatically applied
- Liquid silicones or plastics
- Draining surface water away from a building by grading
- Provide granular fill under a concrete slab on grade (deter capillary action)
- Install polyethylene film vapor seal over the granular fill
- Footing drains (perforated clay tile) to carry water away from structure
Consists of materials and methods that prevent water under hydrostatic pressure from penetrating those parts of a building in direct contact with the earth.
- Several layers of asphalt-saturated felt (2 or 3 -ply) hot mopped together with tar or asphalt pitch.
- Most common method for subsurface walls
- Applied to the earth-contacting side of the wall allowing water pressure to force the membrane against the waterproofed surface.
- Protect membrane with a coat of cement plaster, fiberboard, or masonry wythe.
- A device used to create waterproof construction joints in walls and floors below grade.
- Non-corrosive metal or plastics
- Permit movement without rupture
- Most common and predictable source of moisture that can damage a structure.
- Control depends on the form and type of roofing
- Materials and methods used to weatherproof the exterior top surface of a structure.
- Factors affecting selection: climate; fire resistance; type; slope; weight; durability; cost; appearance; personal preference
- Measured by: SQUARE of surface area (100 sq. ft.)
Roof Selection Factors
- Fire Resistance:
- Personal Preference:
- Affects durability of roofing materials.
- Strong winds: damage slate, tile, asphalt shingles
- Hail: punctures roll roofing, break tiles
- Extreme temperatures: expansion / contraction of metal
- High temperature and ultraviolet radiation: affect asphalt
- Salt, air, smoke, industrial gas: corrodes metal (not copper, lead or terne plate)
- A: effective against severe fire test
- B: effective against moderate fire test
- C: effective against light fire test
- Shed: single slope
- Gable: 2 slopes which meet at a ridge
- Intersecting Gable: 2 gables in opposite direction (Valley downward slope intersection)
- Hip: 4 sides slope and meet at one point
- Mansard: hip with a pitch change high above
- Gambrel: gable with a pitch change high above
- Flat w/ parapets: walls extend beyond top of the roof
- Sawtooth: multiple identical systems of vertical with single slope to one side
- (Incline or pitch)
- Expressed as 2:12 (vertical to horizontal units)
- 0-3:12 pitch: bituminous; metal; require continuous waterproof membrane
- 1-4:12 pitch: asphalt shingles; asphalt rolls
- 4-8:12 pitch: all shingles, metals; 5-8 tiles and slate
Affects the design, structure and cost.
- Function of its quality, climate conditions, and installation.
- Asphalt is least durable
- Corresponds to durability
- Relates to appearance
- Most attractive are more expensive
- Asphalt: built-up; shingles; roll
- Wood: shingles; shakes
- Metal: sheet; corrugated; strip
- Clay, cement, slate: tile
- Glass, plastic: sheets
- Plastic: liquid coatings
- Consists of layers of asphalt-saturated felts and hot asphalt cement (bituminous materials) (asphalt or coal-tar pitch)
- Designation: 3-ply; 5-ply (# of layers used over the unsaturated base layer sheathing)
- Slag is placed overtop as a flood coat to protect plies from weather
- Asphalt used for sloping roofs
- Coal-tar used for flat roofs
Asphalt Shingles / Rolls
- Shingles manufactured from asphalt-saturated felt and embedded with weather-resistant mineral surface.
- 3ft strips
- Lapped installation and secured with galvanized roofing nails (3:12 pitch min.)
- consists of rolled asphalt-saturated felt
- 3ft wide rolls
- Lapped installation and secured with galvanized roofing nails (1:12 pitch min.)
- Made from red cedar, cypress, and redwood due to decay resistance.
- Standard sizes; tapered thickness;
- Shakes (hand-split)
- Lapped installation over sheathing and fastened with aluminum or galvanized nails (4:12 pitch min. to allow ventilation)
- Designation: 16" 5/2 (total thickness of butt end of 5 shingles = 2")
- Random (3-14" width) packaged by the square
- Dimension (5-6" width) packaged by 1000
- Need fire protected
- Include galvanized iron, copper, aluminum, terne plate
- Disadvantages: corrosion, galvanic action, expansion / contraction
- Standing / Batten seam: repetitive pattern
- Corrugated: allows more movement
- Tiles: galvanized or aluminum; installed over felt and sheathing secured with similar metal fasteners
- <3:12 pitch: soldered or welded
- 3:12 < pitch: screws or nailed with compatible metals
- Durable; expensive and attractive oxidizing
- Heavy; durable; permanent; fireproof; expensive
- Applied over sloping roof surfaces
- Lapped over preceding course and nailed
- Clay Tile
- manufactured from the same clays used for bricks
- Patterns: greek; roman; Spanish; mission; shingle; english
- Cement Tiletiles manufactured from Portland cement and fine aggregate.
- Less expensive than clay
- Slate Tile
- Tiles quarried from natural rock and split into thin rectangular slabs
- Sizes: 12"x16"; 3/16 to 1/2" thick
- Texture: smooth; rough
- Glass and translucent plastic
- Flat sheets for small areas; corrugated for large areas
- Poor fire resistance; wire-reinforced or fiberglass
- Thermal expansion
- Low strength
- Use: skylights; clearstories; greenhouses; areas requiring light and weather protection
Plastic Coating Roofing
- Single-ply sheets; single-ply with foam; liquid
- Use: curved; thin shelled concrete surfaces
- Substrate must be of a type the coating will bond to
- Condensation of water vapor.
- Higher the air temperature = higher humidity
- Moves from high to low pressure areas and from inside to outside a building
- Moisture forms on the cool side of a material
- Amount of water vapor the air contains in relationship to the amount it could contain.
- Expressed as %
100% relative humidity when water vapor turns into a liquid
- Materials that prevent the passage of water vapor.
- Types: aluminum foil; sheet plastic; asphalt-saturated felt
- Installed on warm side
- Slow down heat gain or loss to improve human comfort and conserve energy.
- Conduction: when materials or objects are in direct contact.
- Convection: process that occurs in a fluid medium (air or liquid)
- Radiation: take place between two objects not in contact and not shielded from each other
Thermal Control Methods
- Caulking and weatherstripping: cracks; openings
- Tinted, reflective or insulating: windows
- Thermal insulation: wall; roof
- Thermal Resistance
- High degree of reflectivity
- Thermal conductivity (expressed as U)
- k = 1/R
- Arranged from least to most insulating
- Loose fill
- Board or sheet
- Batt or Blanket
Loose Fill Insulation
- glass or mineral wool, vermiculite, perlite
- used for wall cavities and flat air spaces such as attics
- Rvalue=3.90 (4" thick)
Batt or Blanket Insulation
- glass or mineral wool enclosed by paper or aluminum - vapor barriers available
- used for air spaces in framed walls, floors, and ceilings
- Rvalue=11.00 (3 1/2" thick)
Board or Sheet Insulation
- cork, glass or mineral fibers, paper pulp
- used for wall sheathing and rigid roof insulation
- Rvalue=2.75 (1" thick)
- aluminum foil often in combination with layers of paper and air spaces
- used for roof, wall and floor insulation plus vapor barrier
- Rvalue=1.39 (1" air space with 2 reflective surfaces)
- plastics, spray type or panels
- used for sheathing, irregular spaces
- Rvalue=6.00 (1" panel)
Material used to provide a seal and prevent water penetration at joints exposed to the weather, intersections or materials, and expansion or contraction joints.
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