Identify the material behind the name
Traditional roofing felt uses an asphalt-saturated mat. Synthetic underlayment uses polymers such as polypropylene or polyethylene. Both belong to the underlayment category, but individual products have different specifications. GAF explains the differences between felt and synthetic underlayment.
The word felt can be misleading
A product name containing “felt” does not always mean traditional asphalt felt. For example, GAF FeltBuster Synthetic Roofing Felt is a synthetic product. Put the full manufacturer name, product name and SKU on the order so the warehouse can identify the intended roll.
Check coverage and the project specification
Use the exact product’s published coverage when preparing quantities. Ask your contractor to confirm the roll count for the project’s requirements. Do not assume two similarly sized rolls are interchangeable, or transfer one product’s exposure or performance claims to another. Where the takeoff calls for a separate leak barrier, list it separately from the general underlayment.
Order the specified accessories at the same time
Include any fasteners and related materials specified for the selected product. Your contractor and the current manufacturer documents should determine compatibility and installation requirements. Compare catalog products and ask the warehouse to confirm the exact product, selling unit and availability.
