Reconstruction Blog
Drew Ballensky is general manager of Duro-Last Roofing, Inc.’s central U.S. facility in Iowa and company spokesman for Duro-Last’s cool roofing, sustainability and architectural education programs. He is past-president of the Chemical Fabrics and Film Association and chairman of CFFA’s Vinyl Roofing Division. Drew earned his bachelor’s degree in industrial technology from the University of Northern Iowa and master’s degree in business administration from Florida State University. Drew has over 29 years experience in business and industry in various engineering and managerial capacities. He has worked in the U.S. and Canadian operations for a major international manufacturer of pre-engineered steel buildings, was a financial analyst with a major athletic apparel manufacturer and was an owner of a general contracting company.
Follow Reconstruction Blog:
         

On reroofing projects, PVC and asphalt should never meet

August 10, 2011

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.
(http://duro-last.com/blog/2011/07/pvc-is-to-asphalt-like-oil-is-to-water/)

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. 
         
 
 

Other posts from this author

Comments on: "On reroofing projects, PVC and asphalt should never meet"

Comments

ASphalt and PVC

Dear Drew - thanks for that information - I had no idea these two major roofing components had adverse effects on each other. Could you please explain why and give examples of what happens when they come into contact?

Also I would like to point out that while it is true that PVC is flame resistant, others should know that when it does burn it releases a lethal carcinogen. Isn't there another product the industry could substitute for PVC which would pose less of a risk to fire fighters and the environment and which might not have problems ineracting with asphalt, which here in NYC is on nearly every roof?

Thanks,

Will

 very interesting!..Thanks..

 

very interesting!..Thanks..

Helpful warning

This is a great point. Many existing buildings do in fact use asphalt roofing and with the desire or even need to replace the roof with something more environmental conscious, material considerations are important. Some may choose to simply cover the existing material to save costs but as you point out, actions need to be taken if this means using PVC. Thanks for providing this information.