Roof Sailing Roofing Materials and Underlayment 1 — Questions and Answers
Question 1: What is the minimum weight rating for felt underlayment used under asphalt shingles in the US?
- 10 lb felt
- 15 lb felt (Correct answer)
- 30 lb felt
- 45 lb felt
Correct answer: 15 lb felt
ASTM D226 Type I (15 lb felt) is the minimum standard underlayment accepted under asphalt shingles for most US building codes, though 30 lb is required in high-wind and severe weather zones.
Question 2: What is the primary advantage of synthetic roofing underlayment over traditional felt?
- Lower cost
- Higher tear resistance, lighter weight, and improved UV stability (Correct answer)
- Easier to remove during re-roofing
- Better fire rating
Correct answer: Higher tear resistance, lighter weight, and improved UV stability
Synthetic underlayments are engineered polypropylene or polyester sheets that are lighter, stronger, and more UV-resistant than organic felt, reducing installer fatigue and damage during installation.
Question 3: Ice-and-water shield (self-adhering membrane) is required in all US climate zones at which roof location?
- Along all horizontal joints
- At eaves in areas with freezing temperatures (Correct answer)
- On all south-facing slopes
- Along all ridge lines
Correct answer: At eaves in areas with freezing temperatures
IRC Section R905.1 requires ice-and-water shield at eaves in regions where the average January temperature is 25°F or less to protect against ice dam infiltration.
Question 4: What does the 'Class A' fire rating on asphalt shingles indicate?
- Maximum wind resistance
- Highest level of fire resistance per ASTM E108 (Correct answer)
- Impact resistance
- Maximum algae resistance
Correct answer: Highest level of fire resistance per ASTM E108
A Class A fire rating per ASTM E108 indicates the shingles provide the highest level of resistance to severe external fire exposure, making them suitable for use in high fire-risk areas.
Question 5: What is the standard width of a roll of roofing underlayment?
- 24 inches
- 36 inches (Correct answer)
- 48 inches
- 60 inches
Correct answer: 36 inches
Standard roofing underlayment rolls are 36 inches (3 feet) wide, a dimension designed to allow efficient installation with standard overlap patterns on residential roofs.
Question 6: Which shingle material is most commonly used for residential roofing in the United States?
- Wood shake
- Clay tile
- Asphalt (fiberglass-reinforced) (Correct answer)
- Metal standing seam
Correct answer: Asphalt (fiberglass-reinforced)
Fiberglass-reinforced asphalt shingles dominate the US residential market, accounting for over 75% of installations due to their cost-effectiveness, durability, and ease of installation.
Roof Sailing Roofing Materials and Underlayment 1
What is the minimum weight rating for felt underlayment used under asphalt shingles in the US?