Which of the following standards should be specified for asphalt felt underlayment used with tile roof systems?

Which of the following standards should be specified for asphalt felt underlayment used with tile roof systems?

• A. ASTM D4869, Type IV
• B. ASTM D226, Type I
• C. ASTM D226, Type II
• D. ASTM D226, Type III

Answer: (A)

In tile roof systems, the underlayment needs to be a fairly robust asphalt-saturated felt that can resist tearing, punctures, and the rigors of installation and weathering. The standard that covers this specific use is ASTM D4869, with Type IV representing the higher-strength, more durable grade appropriate for tile applications. Type IV underlayment is designed to meet the performance requirements needed under tile—stronger tear and puncture resistance and better durability—so it provides reliable moisture protection beneath the tiles. The older standard, D226, defines lighter felts (Types I–III) and does not specify a Type IV option, making it less suitable for tile roof systems where higher performance is required. Therefore, D4869 Type IV is the correct specification for asphalt felt underlayment used with tile roofs.

In tile roof systems, the underlayment needs to be a fairly robust asphalt-saturated felt that can resist tearing, punctures, and the rigors of installation and weathering. The standard that covers this specific use is ASTM D4869, with Type IV representing the higher-strength, more durable grade appropriate for tile applications. Type IV underlayment is designed to meet the performance requirements needed under tile—stronger tear and puncture resistance and better durability—so it provides reliable moisture protection beneath the tiles.

The older standard, D226, defines lighter felts (Types I–III) and does not specify a Type IV option, making it less suitable for tile roof systems where higher performance is required. Therefore, D4869 Type IV is the correct specification for asphalt felt underlayment used with tile roofs.