CSLB General Building (B)Finishes and Building EnvelopeMedium
A roofing contractor is selecting an underlayment product for a steep-slope composition shingle roof and wants a self-adhering, rubberized asphalt membrane suitable for use in valleys and eaves rather than standard felt. Which ASTM standard governs this type of self-adhering underlayment?
- AASTM D226
- BASTM D4869
- CASTM D1970
- DASTM D3161
Show answer & explanationAnswer & explanation
Correct answer: C. ASTM D1970
ASTM D1970 covers self-adhering polymer-modified bitumen sheet materials used as steep-slope roofing underlayment, commonly used for ice barriers, valleys, and eaves. ASTM D226 governs asphalt-saturated organic felt, D4869 covers asphalt-saturated organic felt for shingle underlayment, and D3161 covers wind resistance testing of asphalt shingles, not underlayment composition.
Why the other options are wrong
- A. D226 governs standard asphalt-saturated felt, not self-adhering membranes.
- B. D4869 covers asphalt-saturated organic felt underlayment, not self-adhering membranes.
- D. D3161 is a shingle wind-resistance test standard, unrelated to underlayment type.
Underlayment ASTM Standards
Different ASTM standards classify roofing underlayment materials; D1970 specifically covers self-adhering polymer-modified bitumen sheets used for ice barriers and critical drainage areas.
- ASTM D1970: self-adhering polymer-modified bitumen underlayment
- ASTM D226: asphalt-saturated organic felt
- ASTM D4869: asphalt-saturated organic felt for shingle underlayment
Memory trick: '1970 sticks' — D1970 is the self-adhering sticky membrane standard.