MOISTURE + THERMAL Flashcards
What is the difference between dampproofing and waterproofing?
Dampproofing is protection from water that is not under hydrostatic pressure and waterproofing is protection from moisture and water that is subject to hydrostatic pressure
Name five types of dampproofing
Admixtures, bitumous coatings, cementitious coatings, membranes, and plastics
What do admixtures do?
Fatty acid, mineral oil, and powdered iron… They may reduce the strength of concrete but they make it much less permeable to water
How does powdered ironwork?
Used in admixtures and cemented just coatings, it expands when it oxidizes, making a tighter seal
How do you protect waterproofing?
A leak in waterproofing from backfilling is not good… you lay a protective board before backfilling
What do you use to seal construction joints?
Waterstops
The perfect insulation would be a
Vacuum
Most insulation is designed to…
Create air pockets that are small enough to prevent convection but large enough to prevent the direct transfer of heat by conduction between the materials
Definition of a BTU
Hey British thermal unit, the amount of heat required to raise the temperature of 1 pound of water by 1°F
What does the K value or basic unit of conductance represent?
The number of BTUs per hour that pass through one square foot of a material 1 inch thick when a temper differential is 1°F
The long term thermal resistance value (LTTR) is specifically for
Foam insulation
What is thermal drift?
The long-term changes in the thermal resistance of foam insulation over time… Measured by LTTR
Lues – fill insulation is used for places where…
It is difficult to install other types of insulation, like cells of concrete blocks, plumbing chases, and attic… Also in retrofit applications
One of the downsides of loose fill insulation is that it always…
Settles
What is rock wool?
A fibrous material formed by blowing molten basalts rock under pressure… Slag wool being the most common, from blast furnace flag
Vermiculite may contain…
Asbestos
In addition to holding the insulation and place the craft paper on batt insulation does what?
Acts as a vapor retarder
Because if it’s superior water resistant qualities, extruded expanded polystyrene is the only insulation recommended for what two kinds of spaces?
Protected membrane roof systems and below grade insulation
What are insulated concrete forms?
Interlocking foam insulation blocks that serve as formwork for pouring concrete walls and remain in place to insulate the wall and serve as a backing for the chipboard
What is a SIP?
Structural insulated panel, to outer skin is bonded to an inner core of residents living material usually expanded polystyrene
What is the dewpoint?
The temperature at which water condenses from vapor
3 kinds of roofing tile
Slate: expensive, durable, fire resistant
Clay: lots of shapes, durable, fire resistant, also expensive
Concrete: less expensive than clay but also durable and fire resistant
5 kinds of metal roof
Copper, galvanized iron, aluminum, terneplate, Monel metal
What do you need between the metal roof and the asphalt roofing felt on terneplate roofs and why?
A rosin paper to keep the asphalt from oxidizing the tin
Describe ponding
When some build up of water creates deflection, in turn allowing more water to pond
What is a built-up roof?
A layer cake of overlapping layers of felt and asphalt or coal tar with a final layer of gravel on top
What is a cricket?
A saddle shaped projection around an obstacle to divert drainage
What is a pitch pan?
Small metal enclosure around a roof mounted projection filled with bitumous material
What are modified bitumens?
A type of single-ply roof made of chemically enhanced bitumen with a reinforcing fabric
What are thermoset plastics?
A type of single-ply roof material that softens when hot and regards a when cold
What is EPDM?
A manufactured thermoset plastic membrane that can be mechanically fastened, used in a membrane roof, taped together, etc
What is the difference between PVC and TPO roofs?
Both white-colored single-ply roofs, TPO is cheaper
Because they are white they reflect back 78% of heat
Where do you use elastic liquid roofing?
Over roofs with complex shapes (as well as below-grade waterproofing)
Neoprene is one
Some materials you can make flashing out of
Galv. Stl, S.S., alum, copper, plastic
How often do you need expansion joints in roofs?
Every 100-150 ft in masonry
Every 200 ft in concrete
Why are expansion joints critical in roofs?
Extremes in temperature
What are smoke vents?
They allow smoke to escape in a fire
High-performance feeling allow what percentage of movement? Low performance sealants only allow what percentage of movement?
High: 25%
Low: about 5%
What is EIFS?
Exterior insulation and finish system, a cladding assembly with a wet cementitious finish over a rigid insulation board attached to building sheathing
What are the 3 1/2 types of EIFS?
(PB): polymer-based, where the EIFS is basically glued to the building sheathing
(PM): polymer modified, which is mechanically adhered to the sheathing
(MB): mineral-based, where the system uses Portland cement stucco as the topcoat
(A high impact PB system includes a heavy duty fiberglass mesh an additional layer of base coat… But in general the PM system is better at taking impact)
What is the difference between permeable and pervious?
Permeable is capable of being penetrated by water without causing rupture displacement. Pervious permits leaks or flows of water through cracks or other openings.
What is the difference between water-resistant, water-repellent, and waterproof?
Water-resistant has capillary pores that permit leakage of water. Water-repellent cannot transmit water by capillary action, but it still made transit water under pressure. Waterproof means it is completely impervious to water, under pressure or not.
Three damp proofing materials
Asphalt base coatings (in two coats), cement plaster (troweled or pneumatically applied), and liquid silicones or plastics
What is the most common form of waterproofing? What form does it usually take?
Membrane waterproofing, usually several layers of asphalt saturated felt, hot mopped together with tar or asphalt pitch
Where do you install water stops?
In construction joints below grade
A range for tile and slate roof pitch
5:12 - 8:12
A range for shingles and metal roofs pitch
4:12 - 8:12
Hey range for a bitumous roof
Pitches
0:12 - 3:12
What is a square in regards to a roof unit of measure
It equals 100 ft.²
What is under the gravel coat in a built-up composition roof?
The flood coat
What does shake mean in regards to wood shingles?
Hand split
What does 16 – inch 5/2 random shingles mean?
The shingles are 16” long, of random width, and 5 of the butt ends stacked on top of each other are 2” tall
Metal roofing materials include what 4 metals? And to a lesser extent what additional three?
Galvanized iron, copper, aluminum and terneplate… Also lead, zinc, and stainless steel
Three kinds of roofing tiles
Clay tiles, cement tiles (less expensive), slate tiles (quarried from natural rock)
Relative humidity
Expressed as a percentage, this is the ratio of humidity to maximum humidity
If air at 50% relative humidity is cool…
It’s relative humidity increases
What can you do to air to give it excellent insulation properties?
Enclose it
Define an insulator in terms of thermal conductivity
A material with a K value of 0.5 BTU per hr per ft.² per °F or less…
What are two advantages of placing them insulation above the membrane?
You protect the membrane from temperature extremes and the membrane, being on the warm side of the inflation, acts as a vapor barrier
Where to put flashing
Joints exposed to the weather, intersections of different materials, expansion or contraction joints
If it’s not exposed, you can make flashing from the following:
- Sheet metals
- Bitumous-coated fabrics
- Plastic
- Other waterproof membranes
Provide expansion joints and Masonry walls every ___ feet
125
In roofs, concrete structures, and steel structures, expansion joints should occur at ___-foot intervals
200
A gravel stop has a higher portion at the perimeter with a minimum of how many inches?
Gravel stop have to be at least 4 inches wide
How big are expansion joints?
1/2 to 1 inch in width
Four ways to waterproof expansion joints
What are stops, elastic joint sealants, metal flashing, or caulking
