Ask the Architect

Fix or replace a rubber roof?

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Q. I have a flat black rubber-sheet roof glued to plywood on my store and several questions about having it either fixed or replaced. I finally looked at it after it leaked recently. Roofers have looked at it and said it can be patched, and recommended re-coating it with a reflective silver paint. They say it will keep the building cooler and the roof will last longer. Do you agree? They also suggested replacing the ceramic tile on the roof edges with a metal cover. Some of the tiles are cracked and someone used tar to fix them, which is now running down the wall (a mess). Can I just replace those tiles? It will cost a lot more ($3,000) to replace the roof. What would you do?

A. There are several different types of “rubber” roofs, with compositions ranging from an asphalt type to PVC, and another called EPDM. The PVC is polyvinylchloride, and the EPDM is ethylene propylene diene-terpolymer membrane. Knowing which roof you have is important because their life spans, attachment and repair are different.

The type of coating, which is an aluminum-based solution, must be compatible, and I recommend a solution with a greater amount of “solids.” It costs more but lasts much longer. The thin coatings break down in a relatively short time, and begin to look like an alligator’s skin as they expand in the heat, losing effectiveness, since their job is to reflect heat. By reflecting the sun’s rays, they prolong the life of the roof membrane. The ceramic tile is a brittle material that expands and contracts readily. It’s usually intended to save money but, again, does the opposite in the long run because it costs more to get the tiles off, cart them away and prepare the roof edge or walls above the roof surface, referred to as parapet walls, for the (better) metal cover.

The big mistake made with roof edging and parapet wall covers, called coping, is that a bent sheet metal cover is often nailed or screwed right through the top of the metal and into the top of the wood-framed wall, which, over time, expands and contracts with the weather and then leaks. There are several reasons to fasten the roof coping and edges more methodically, using a clip system in which the metal cap is fastened by bending the edges in a Z or V shape at the edges and snapped into a hidden channel underneath. Aside from looking much better, the roof is able to resist wind uplift due to the tendency for the wind to rip the membrane off the roof as it drags past the surface. Not only does it cost less over time, but it is code-required and will save your roof and business in a severe storm.

Your roofers sound knowledgeable. Ask to see a recent job to understand what they will do for you. This avoids misunderstandings. Good luck!

© 2016 Monte Leeper. Readers are encouraged to send questions to yourhousedr@aol.com, with “Herald question” in the subject line, or to Herald Homes, 2 Endo Blvd., Garden City, NY 11530, Attn: Monte Leeper, architect.