On reroofing projects, PVC and asphalt should never meet
For a number of reasons, PVC is a popular choice of material on reroofing projects: well-suited to “cool roof” goals, readily recyclable, flame resistant, and highly flexible. It’s important to recognize, however, that PVC membrane products are not compatible with asphalt-based products.
If you replace or re-cover your old asphalt roof with a new PVC membrane, here are some key issues to keep in mind for a quality installation:
- Tear-offs of asphalt roofs often create dust that contaminates a new membrane. Take into account the wind direction, put a tarp over PVC materials placed near the tear-off, ensure that shoes don’t track asphalt over PVC, and complete the tear-off before beginning PVC installation.
- Make sure that compatible sealants are used on the new membrane. Many caulks, sealants, and pitch pocket fillers contain asphalt, and should never be used on PVC.
- If your project involves re-covering the built-up roof rather than tearing it off, a suitable separator must be installed between the old asphalt and new PVC roofing systems.