Questions covered in this guide
Ask for a layer map
A roof bid may list underlayment, deck protection and a leak barrier without showing where they will be used. GAF describes roof deck protection as helping shield the deck from moisture and separately describes leak barriers as helping address wind-driven rain and ice dams. Those brief descriptions do not specify a complete assembly for your house. Ask the roofer to mark the proposed layers on a simple roof diagram.
Name the products and locations
Use one row for each product, with columns for its name, intended location and the document supporting that use. Ask the contractor to explain unfamiliar terms using the diagram. If two bids list different products, request an explanation of the difference in the proposed assembly rather than comparing roll counts alone. Keep the discussion tied to the selected roof covering and its installation instructions.
Clarify the decision before the deck is covered
Ask which details depend on the existing deck condition and which are already settled. Have the roofer identify any local requirements that affect the proposed layers and who will confirm them. Request photographs or another agreed completion record of the installed layers before they are concealed. If a substitute product is proposed, ask for its documentation and any effect on the scope or warranty before accepting the change.
Compare complete work in the budget
Record whether preparation, accessories, installation and disposal are included in the price shown. Ask about temporary weather protection during the job as a separate scope question; a listed underlayment is not an explanation of the contractor's weather plan. The roofing calculator uses a broad project reference and cannot select a roof assembly. Use supplied pricing for the documented system and keep unresolved deck work visible alongside the range.
Putting it into practice
A product-and-location map makes concealed roof layers reviewable. It separates the permanent assembly, substitutions and documentation from the contractor weather plan and unspecified deck repairs.
Sources and supported claims
GAF describes roof deck protection as helping shield the deck from moisture infiltration.
Source ↗ · national · Checked 2026-10-12
GAF separately describes leak barriers as helping protect against leaks associated with wind-driven rain and ice dams.
Source ↗ · national · Checked 2026-10-12