I received the following letter from Todd Kuykendall, Director, Product Management at Georgia-Pacific Gypsum about my article titled “Design and Installation Tips for Single-Ply Roofing Systems”

Dear Roofing Contractor:

I enjoyed the article, “Design and Installation Tips for Single-Ply Roofing Systems” in the January 2012 issue. However, I wanted to bring one thing to your attention that I think was misstated.  In “Tip #11” of the article, author Mike Russo mentions the following:

11. Structural fiberglass-faced gypsum board should not be used as a substrate for fully adhered attachment on parapet walls.

I believe the phrase should have been worded:

11. fiberglass-faced gypsum sheathing boards should not be used as a substrate for fully adhered attachment on parapet walls.

The term “structural” is confusing because gypsum sheathing and gypsum roof boards are not structural. The correct product for the parapets is 1/2 inch (minimum) primed glass mat roof boards (i.e. DensDeck® Prime).  I mention this because there has always been a lot of confusion over the appropriate product to use on parapet walls.  Let me know if you see it differently, or I misinterpreted the wording.

Best regards,

Todd Kuykendall

Director, Product Management

Georgia-Pacific Gypsum

Atlanta, GA

Mike Russo responds:

Thanks for pointing this out, Todd. You are correct. A primed glass mat roof board would be the product to specify as a substrate when fully adhering TPO or PVC roofing membranes to parapet walls.