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  • Ian J Cheadle

Moisture Control


Vapor retarders are the unspoken hero’s of the hardwood flooring installation. They are essentially an insurance policy for your new wood floor. Water vapors can travel through any wood or concrete substate and in most cases we as the installers actually want to allow that to some degree. The purpose of the vapor retarder/barrier is to control the moisture travel to a point that it doesn’t affect the wood without blocking too much moisture and creating a trap for it which will actually accelerate deterioration. That’s where a liquid-applied vapor retarder shines in my opinion.

There are several different products on the market and as a wood flooring professional i have tried many of them. My favorite right now is a product call PU-280 manufactured by Wakol. Another one that I like and may use for reference is Bona R-540. One of my favorite parts about using PU280 over other products is the fact that Wakol color it blue from the factory. This might seem like something that isn’t super important but sometimes it can be very helpful for determining where you have already applied the vapor retarder and where you have not. That is a very crucial detail because one coat can “retard” moisture, which is the goal for wood substrates but two coats will actually “block” moisture and that’s the goal for concrete substrates. Under no circumstances though should you apply multiple coats to a wood substrate because that could cause moisture trapping as mentioned before that can rot both the finished floor and the subfloor beneath.

Another feature with PU280 that i really enjoy is the dry time. In most cases an installer can work on top of the PU280 applied surface within a couple hours. In the handful of times I’ve used the Bona product I’ve had to put a fan on it and allow it to dry completely overnight (8 hours at least) before beginning installation. Sometimes it works out that I’m applying vapor barrier at the end of the day and can allow for this dry time but in most cases that isn’t an option. So for that reason alone I feel like Wakol has the superior product.

One other thing that is worth mentioning is on the subject of glue-assisted installs. Glue-assisted means that I’m using a caulk-style gun to apply wood flooring adhesive to the backside of the boards or to the subfloor itself in strategic places or sometimes on the entire floor. I’ll explain the purpose for this and the benefits to the consumer in another article about glues specifically. But where it ties into vapor barriers is important for this part. Adhesives are helpful to some degree on any install but with a fluid applied vapor retarder like PU280 they gain superpowers. As the vapor retarder encapsulates any surface contamination on the surface of the subfloor its also creating a texture on top as it dries that allows for the best mechanical bond to adhesives. As the glue squishes into the wood fibers on both sides and into the pours of the dried pu280 it creates a mechanical lock that may have otherwise been contaminated or not available at all. This can be tested by gluing two similar boards to a substate that is partially coated with vapor retarder and allowing to dry then pulling the boards back off. There is usually a significant difference in bond strength between the samples.

These are a handful of the many reasons that vapor-retarding products are a crucial part of the installation process that I use at Dayton Hardwood Co. to provide the consumer with the best possible finished product. If you have any questions about any of the information or products mentioned please leave a comment below, send a direct message on Instagram, or send me an email and I’ll be happy to discuss. Thanks for taking time to read this and I hope it helps your wood flooring project.

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