Can Old Peel-and-Stick Underlayment Stay During a Reroof?
Bulletin revision: February 1, 2021
What to discuss when an old self-adhered membrane will not come off cleanly, including deck inspection and extra layers.
The shingles come off, but the waterproofing membrane underneath stays stuck. This deserves a planned decision before another layer goes over it.
Atlas starts with removal when practical
Its bulletin recommends removing old self-adhered underlayment when that can be done without damaging the deck. Removal makes deck inspection possible and avoids unnecessary buildup and uneven transitions.
A conditional exception, not a blanket permission
Atlas allows a second layer in certain circumstances when a single existing layer cannot be removed without deck damage. The bulletin excludes Florida and defers to local requirements. It calls for removing all layers when two or more are already present.
Where the exception applies, Atlas specifies offset laps and extending the new membrane at least eight inches beyond the old membrane to soften the transition. These are Atlas-specific provisions, not instructions to apply automatically to every roof system.
What belongs in your estimate?
How many membrane layers are present?
What areas of the wood can actually be inspected?
Which manufacturer’s instructions support the proposed approach?
What deck replacement is included, and what requires additional approval?
Do not cover up an unanswered question
Ask for photographs at the decision point, while the roof is open. If the contractor proposes leaving material in place, request the reason and the applicable product detail in writing. Deck replacement may be necessary; new underlayment does not resolve damaged wood beneath it.
Related guide
Explore the connected roof detail
Manufacturer references
Atlas: Self-Adhering Underlayment Removal (2021 revision).
Prepared by Barnes N’ Roofs. Technical sources reviewed October 14, 2026. Manufacturer requirements vary by product; this homeowner overview does not replace current installation instructions or applicable local requirements. Project photography is illustrative and does not establish the shingle brand or a concealed condition.
GAF technical bulletin reference
Bulletin revision: February 1, 2021. This is the date of the manufacturer source, not a claim that this website guide existed on that date.
Read GAF: Re roofing and self adhered leak barriers
This homeowner summary explains the cited bulletin. The complete manufacturer document and current product instructions govern the installation details. A requirement for one manufacturer or product should not be transferred to another without checking.