United States
Hong KongThermal and Moisture Protection
Five of 115 scored questions covering roofing systems and slope, flashing and waterproofing, insulation and vapor retarders, and sealants and envelope detailing.
Five questions on keeping water and heat where they belong. The two halves are related and are usually tested separately.
The four subtopics
- Roofing systems, slope and drainage
- Flashing, waterproofing and dampproofing
- Insulation, vapor retarders and air barriers
- Sealants, joints and building envelope detailing
Slope decides the roofing answers
Roof slope is expressed as rise over a 12 inch run. A slope of 3 in 12 or less is generally treated as low slope.
That threshold governs which systems are permitted and whether double underlayment is required for asphalt shingles. Most roofing questions turn on it.
| Item | Figure |
|---|---|
| Slope expression | Rise over a 12 inch run |
| Low slope threshold | 3 in 12 or less, generally |
| Ice barrier extent | 24 inches inside the exterior wall line, in cold climates |
R-value and U-factor
R-value measures resistance to heat flow. U-factor is its reciprocal and measures transmission.
Higher R is better insulation. Lower U is better performance. Questions offer both and rely on candidates reaching for the wrong direction.
On the warm side of the insulation in a heating climate. Put it on the wrong side and moisture condenses inside the assembly, which is the failure the rule exists to prevent.
Dampproofing against waterproofing
Dampproofing resists moisture. Waterproofing resists water under hydrostatic pressure. They are different products for different conditions, and the exam asks which one a situation requires.
Common questions
How many thermal and moisture questions are there?
5 of the 115 scored questions.
How is roof slope expressed?
As rise over a 12 inch run. A slope of 3 in 12 or less is generally treated as low slope.
What is the difference between R-value and U-factor?
R-value measures resistance to heat flow and U-factor is its reciprocal, measuring transmission. Higher R and lower U are both better.
Where does a vapor retarder go?
On the warm side of the insulation in a heating climate.
What is the difference between dampproofing and waterproofing?
Dampproofing resists moisture; waterproofing resists water under hydrostatic pressure.