CPES and plywood checking

[Dean K]

Hi,

Would CPES keep a 1/4 inch plywood roof from checking (splitting) over time? I know there are several folks here that have used CPES as their primary waterproofing.

Any input would be appreciated!

Dean K

[Miriam C.]

CPES should act like a glue if it penetrates the layers of you plywood. Have you called Rot Dr. you can google them and call. He will better be able to answer that.

I used epoxy on my cracked and splitting out plywood and it is working great. Mine had a very thin veneer on the surface and nothing for CPES to really sink into so I couldn't use it.

[Micro469]

CPES is a very watery form of epoxy. Used as a waterproof. It soaks into the wood . I would use it to help protect my roof, but also cover it with paint, epoxy, aluminum, or what have you. You might call it your first defence against damage in the future.....

I used it on the bottom floor of my trailer. It took five coats before it wouldn't absorb anymore. Then I painted it. That was 2 years ago... still no damage.

[Arne]

The answer is a conditional yes from me. I've used it on 2 ply roofs with never a problem..

Remember, until you paint or cover the roof, keep it out of the sun. Sun and heat are the major causes of cracking of the top layer of ply. That layer is already stressed, and if it dries, it will split.

Once I have put cpes on the roof ply, I have put it out in the sun for short periods with no problem... but, better to be careful.

The conditional part is because I think the cpes will only penetrate ply to the first layer of glue, so wouldn't depend on it to be completely fool-proof especially in AZ in the summer.

[schaney]

Dean, there are a lot of variables. Sealing out moisture with something like CPES helps. The type of plywood you use is a big factor. Fir plywood is more prone to checking than others like marine grade Okoume. The stress of bending plywood around the curve of a roof it can cause checking. Big temp swings make wood expand and contract possibly causing checking. As others have said, maybe.

[Steve_Cox]

I would suspect the thickness of the epoxy coating has much to do with the checking prevention. New plywood - one coat of CPES = water resistant, 3 coats of CPES waterproof. But....CPES was developed to turn rotten wood (not plywood) into a solid mass, negating the need to replace it. For about the same cost and less the chemical hazards you can coat and encapsulate the plywood with epoxy and have a much thicker, more durable substrate for your finish coating. Just my opinion based on having done my share of epoxy work over the years and using CPES on plywood and on rotten wood as well.