I am an architect and have a small project to rebuild a couple of cantilevered decks which have collapsed. It is on an apartment building. The existing decks have concrete topping which we will remove. That leaves a plywood substrate (new and sloped).
The builder has proposed using an acrylic polymer, fiberglass reinforced waterproof system. The product is Excel-Coat by Excellent Coatings Inc.
Wall flashing, according to the manufacturer should be gsm with the Excel-coat lapping over and a urethane sealant at the joint. So the excel coat does not travel up walls.
The advantage of this system is modest first cost and ease of installation.
I do not have direct personal experience with this product. Years ago (say 25) we used to use other toppings on plywood, like Dex-o-tex. I never regarded them as being of very good quality and being conservative around water I never used them on my own projects.
I wonder if the technology has matured into something much better and whether anyone has any experience with this particular product or products of this kind? The manufacturer’s warranty is 1 year.
Thanks,
Donald Wardlaw
Replies
Check out WWW. duradek.com a 10 year warranty. looks better & more durable.
We are doing a similar project. The deck had some type of thin cement coating on it origionaly. Under that there was a layer of some type of underlayment. About a 1/4" thick. Then the plywood subfloor. THey had a problem around the posts with water leaking in behind the caulking. A lot of the posts had water damage and one needs to be replaced. The product that we chose is called Dexcelent. Made by UPI Sealant products. We will be putting down the new surface in the next week or so and I will let you know how it worked.
Checking the product specs on Dexcelent, it is generically the same class of product as Excel-coat, an acrylic polymer. I suspect the edge flashing details would be the same, and they are one of the things that troubles me most about these products. The product lives mainly in the deck field, which is seldom where the problems occur. It is the edge flashing details where decks mainly leak and with these products it is a mix of systems, typically involving sheet metal flashing, so the deck manufacturer has minimal liability if any at all at the area of most likely future failure. I am also troubled by what will likely be different rates of thermal expansion and contraction of the flashing and the topping. Lastly, I see that while Excel-coat offers a 1 year warranty, which I consider inadequate, Dexcelent offers none at all.
At this point in the research, the Duradeck product with a 10 year warranty seems like a better way to go than either Excel-coat or Dexcelent. In particular I like the way the material turns up vertical surfaces so there is no change in materials at the point of most likely future failure.
I begin to suspect that many builders like the acrylic polymers because they are fairly easy to install and look good when done. But I think that is an inadequate basis to judge long term performance.
Still working on this and I appreciate all the comment.
Donald