GAF Roofing Materials & Installation Techniques 2 — Questions and Answers
Question 1: What is the minimum recommended headlap for standard 3-tab asphalt shingles installed on a roof with a 4:12 pitch?
- 1 inch
- 2 inches (Correct answer)
- 3 inches
- 4 inches
Correct answer: 2 inches
A 2-inch headlap is the standard minimum for 3-tab shingles on slopes of 4:12 and above to ensure proper water shedding.
Question 2: Which type of underlayment is best suited for use under metal roofing to prevent galvanic corrosion?
- Standard #15 felt
- Synthetic non-woven underlayment (Correct answer)
- Self-adhering modified bitumen
- Rubberized asphalt peel-and-stick
Correct answer: Synthetic non-woven underlayment
Non-woven synthetic underlayments are preferred under metal roofing because they do not retain moisture and lack the acidic compounds found in felt that can accelerate corrosion.
Question 3: When installing GAF Timberline shingles, what is the standard exposure (reveal) for each course?
- 4 inches
- 5 inches
- 5-5/8 inches (Correct answer)
- 6 inches
Correct answer: 5-5/8 inches
GAF Timberline architectural shingles have a standard exposure of 5-5/8 inches as specified in the manufacturer's installation instructions.
Question 4: What roofing nail length is typically required when re-roofing over an existing layer of asphalt shingles?
- 1 inch
- 1-1/4 inch
- 1-3/4 inch (Correct answer)
- 2-1/4 inch
Correct answer: 1-3/4 inch
When re-roofing over an existing layer, longer nails (typically 1-3/4 inch) are needed to penetrate through both shingle layers and into the decking.
Question 5: Which flashing material is most compatible with cedar wood shingles to avoid staining?
- Galvanized steel
- Aluminum (Correct answer)
- Copper
- Lead-coated copper
Correct answer: Aluminum
Aluminum flashing is preferred with cedar shingles because it does not cause the tannin staining that copper produces when rain washes over it onto the wood.
Question 6: What is the purpose of a drip edge on a roofing system?
- To hold the first course of shingles in place
- To direct water away from the fascia and into the gutter (Correct answer)
- To ventilate the attic space
- To provide a nailing surface at the eave
Correct answer: To direct water away from the fascia and into the gutter
Drip edge metal directs water runoff away from the fascia board and into the gutter, protecting the wood from moisture damage.
Question 7: According to best practices, where should nails be placed on a standard 3-tab asphalt shingle?
- 1 inch above the adhesive strip
- Along the nailing zone, just above the cutouts (Correct answer)
- 1/2 inch below the top edge
- Centered on the exposure area
Correct answer: Along the nailing zone, just above the cutouts
Nails should be placed in the manufacturer-designated nailing zone, typically just above the cutouts and below the adhesive strip, to ensure proper fastening and wind resistance.
GAF Roofing Materials & Installation Techniques 2
What is the minimum recommended headlap for standard 3-tab asphalt shingles installed on a roof with a 4:12 pitch?