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Waterproof A Plywood Roof Deck with Liquid Rubber: Easy Steps

Here’s the EASY DIY steps and tips I used to waterproof a plywood roof deck with Liquid Rubber Deck Coating. And, how it looks 2 years later!

Waterproof A Plywood Roof Deck or Balcony

In the Spring of 2020, I was busy, busy building a big playhouse for my kids. I designed it to look like a mini version of our barn.

But, unlike the barn, the playhouse has a recessed upper deck on one half of the roof. So, I had to figure out how to waterproof a plywood roof deck.

This post goes over how to waterproof a plywood roof deck or balcony with Liquid Rubber Deck Coating. Spoiler Alert, I love this stuff!

In fact, it looks just like it did 2 years ago when I used Liquid Rubber on the plywood roof deck.

Image of a Plywood Roof Deck with Liquid Rubber Deck Coating. Text says "DIY Steps to Waterproof a plywood roof deck".
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And, for the last 2 years, the Liquid Rubber Deck Coating has worked great at stopping the rainwater from penetrating into the plywood deck. It really does make a watertight barrier!

Liquid Rubber Deck Coating can even be used to waterproof the inside of wooden planters. It is a clever way to keep water in your soil while protecting the wood planter from water damage.

OK, let’s get to those steps for how to waterproof a plywood deck with Liquid Rubber Deck Coating.

How-To Video

If any of the written steps are confusing, watch this video to see the steps to apply Liquid Rubber.

Waterproofing a Plywood Roof Deck or Balcony with Liquid Rubber Deck Coating!

Does Liquid Rubber Work on Flat Plywood Decks?

There are a few ways to make plywood waterproof outdoors. But, most of them only work on vertical surfaces or flat plywood surfaces that won’t be walked on.

But, after 2 days or research, I decided that using Liquid Rubber Deck Coating would be the best way to waterproof my plywood roof deck.

I used Liquid Rubber to waterproof my plywood deck because of how easy it is to use, it’s durable enough for foot traffic, it comes in lots of nice colors, and because of all of the great reviews it has on Amazon.

Is Liquid Rubber Waterproof?

Yes! Liquid Rubber Deck Coating is a brush on liquid coating that hardens into a durable, waterproof membrane.

How Much Liquid Rubber Deck Coating Do You Need?

So, how much Liquid Rubber Deck Coating do you need? It depends on how big your plywood deck, roof deck, or balcony is, really.

I used 5 gallons of the Liquid Rubber on my 75 square foot deck. I applied 5 thick coats at about 1 gallon per coat.

Liquid Rubber recommends 3 to 4 coats for waterproofing areas. They say you can cover about 100 square feet per gallon.

That’s probably right, my coats were probably thicker than they needed to be. And I applied extra coats on the edges just to be extra safe.

I ended up applying more than the recommended 4 coats because I wanted to use up the full 5 gallon bucket and extra waterproofing never hurts, right. 🙂

Also, just so you know what to expect, I used maybe a quarter of a gallon of the Liquid Rubber Primer on my 75 square foot deck.

I would recommend measuring the length of all of the edges and seams between pieces of plywood to get an exact measurement for how much geo-textile you need.

Here’s the deck before I applied the Liquid Rubber Deck Coating. The deck slopes slightly down to the open edge to help the water run off the deck. I also have an L-shaped piece of flashing over the plywood and behind the siding to stop any water from being trapped back there.

All Materials Needed

Be sure to always read the directions on the containers to be sure you know how to waterproof a plywood deck.

They could always change a formulation or the instructions after I write these steps. Or, you’re plywood deck, roof or balcony might have special circumstances I don’t cover in this tutorial.

AND, you can pick a smooth or textured version of Liquid Rubber, depending on what you want to use it for. A textured surface might be best if you’ll be walking on it with wet feet. Like near a pool.

DIY Steps to Use Liquid Rubber Deck Coating

Step One

Start by patching any gaps in the plywood with Minwax Exterior Wood Filler or similar. Let dry and sand smooth.

Step Two

Then sand the plywood and any sheet metal that will also have the Liquid Rubber Deck Coating applied to it. I used 40 grit sanding discs.

Step Three

Clean off the dust, then apply the primer to the entire surface with a large paint brush.

Apply the geotextile to all edges and where two sheets of plywood meet.

Step Four

Once the primer dries, apply the geo-textile on all edges and seams on the plywood deck, roof or balcony. Use the Liquid Rubber Deck Coating under the textile to stick it to all seams.

The Liquid Rubber Deck Coating is applied under and over the geo-textile.

Once the coating under the geo-textile mostly dries, you can apply a coat over the geo-textile. You can see how I do that in the video above.

Here’s the deck after all of the geo-textile was applied.

Step Five

Let that dry before applying the full first coat of Liquid Rubber on the surface. Use a paint brush along all edges and a roller to apply the Deck Coating to the surface and partially up the wall to waterproof those areas.

Let each coat dry completely in between.

Applying the poured rubber, Liquid Rubber Deck Coating to the plywood deck.

I used a roller to quickly apply the Liquid Rubber to the middle. I used a brush on the edges. You might notice that I also applied the Liquid Rubber 1″ up the walls.

Don’t worry, you can paint over that part with an exterior grade paint and primer in one (like Behr’s).

Easy to follow DIY steps for how to waterproof a plywood deck, roof, or balcony with a Liquid Rubber Deck Coating. How to waterproof wood outside. How to waterproof a deck.
Here’s the finished deck after using Liquid Rubber on the roof deck. Check out my post on building a playhouse shed, or the post on DIY Gable Vent, or the post on the Easy DIY Swing Set to see more from this backyard play area.

That’s it! Easy, right? I love how this deck coating looks and it feels soft on bare feet. It feels like walking on linoleum.

It’s been 2 years since I used Liquid Rubber on the plywood roof deck of the playhouse and it’s still looking great and keeping the water out of the playhouse. Nice!

What If It Rains On Liquid Rubber Deck Coating Before It Dries?

Try to pick a few dry days in a row to waterproof your plywood deck, if possible. I tried doing that, but when you live in a humid part of the south, unexpected showers pop up all the time.

My first coat of the Liquid Rubber Deck Coating was only about 70% dry when it was lightly rained on. Luckily, it didn’t ruin my deck. You can see what happened in the video above.

All of the Liquid Rubber that was dry before the rain stayed dry. And, the spots that were still wet mixed with rain water. They were not drying.

I used paper towels to gently wipe up that wet mixture of the Liquid Rubber Deck Coating mixed with rain.

Once I removed all of that wet deck coating, I let the surface dry, then I applied another full coat of the Liquid Rubber Deck Coating.

Everything dried fine after that. I applied 5 coats in total with a couple extra coats on the edges and around the posts, to be extra safe.

That’s it for how to waterproof a plywood deck, roof or balcony with Liquid Rubber Deck Coating.


Looking for more of my Easy DIY Home Improvement videos? You can see them here, on my YouTube channel. 🙂

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Feeling inspired? Now that you know How to Waterproof A Plywood Roof Deck with Liquid Rubber Deck Coating, you can do it too.

Let me know if you have questions. Don’t forget to sign up for the Abbotts At Home email newsletter to get DIY, Remodeling, and Crafty ideas in your inbox.

Marilyn

Monday 21st of September 2020

This is a great tutorial. Very useful for me as we refurbish our deck. ******************************************************** Thank you for sharing at #OverTheMoon. Pinned and shared. Have a lovely week. I hope to see you at next week’s party too! Please stay safe and healthy. Come party with us at Over The Moon! Catapult your content Over The Moon! @marilyn_lesniak @EclecticRedBarn ********************************************************

Stephanie

Monday 21st of September 2020

So happy to help. Thanks!

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