Compare named products for the proposed roof
Owens Corning describes differences between synthetic and felt underlayments, including handling and water-resistance characteristics. Those comparisons do not make every synthetic product interchangeable or establish one best choice for every roof.
Ask whether the proposed product is approved for the intended shingle or panel covering, roof slope and expected conditions. Where a different membrane is proposed for valleys or other details, identify that product separately rather than calling everything underlayment.
Check preparation and temporary exposure
The condition of the deck matters before underlayment is installed. Owens Corning’s ProArmor instructions call for a prepared, dry, structurally sound substrate. Product instructions also govern application; owners should request the applicable instructions rather than directing a fastening pattern themselves.
Ask how the roof will be protected between removal and completion, including the manufacturer’s limits on exposure. Underlayment visible during construction should not be represented as a permanent finished roof.
Keep system compatibility in the proposal
The underlayment needs to be coordinated with roof-edge flashing, penetrations and the covering. If a warranty program specifies particular components, have the contractor identify the written requirement and show that the proposal includes them.
- Name the manufacturer and exact product.
- State where each underlayment or specialty membrane will be used.
- Confirm the product is suitable for the selected roof covering.
- Identify temporary-protection responsibilities during weather delays.
- Document substitutions before installation.
Verify before the layer is concealed
Ask for product packaging information and photographs of the installed underlayment and critical transitions. Keep those with the final roof records. This makes future troubleshooting more useful than an invoice that only says “new underlayment.”