Can You Use RedGard Over Plywood? (Explained)

Plywood has many benefits. It is a cost-effective solution. It’s available in many finishes and is suitable for use in cold and hot climates.

However, plywood also has some drawbacks. For instance, you can’t tile directly over plywood. The movements experienced in the plywood will be transferred to the tiles causing them to crack or fall.

Homeowners interested in tiling over plywood have to explore products such as RedGard. These products act as an underlayment that helps minimize the cracking of tiles due to the stresses experienced by the plywood subfloor.

Today’s article will examine whether RedGard can be used over plywood and everything you have to know about these two.


Can RedGard Be Used on Plywood?

Yes, you can use RedGard over plywood. It will adhere just fine and offer benefits such as crack prevention, waterproofing, and uncoupling.

There are two variations of RedGard, and all can be used on plywood. We will discuss each type in detail and its benefits to plywood.

1. Redgard Waterproofing and Crack Prevention Membrane

The first type of RedGard is a liquid waterproofing membrane used for tile installation. One of the reasons builders love this type is because it’s in liquid form. That makes the application pretty easy and quick. Because all you need is a roller.

The liquid RedGard membrane waterproofs the surface of a plywood subfloor, preventing water and moisture from seeping through.

If you have a plywood floor or wall in a bathroom or high moisture area, you should consider this option to make the surface more waterproof and prevent water damage. The other benefit of the liquid RedGard is that it assists in crack prevention.

Applying liquid RedGard over plywood is very easy. You only need to clean the plywood surface, grab a roller brush and apply at least two coats of the RedGard. It should turn dark red when it dries.

2. RedGard Uncoupling Mat

A lot of people are familiar with the above type of RedGard. Only a few know that there is a RedGard uncoupling mat. This option that’s not popular is the best type of RedGard that should be used over plywood.

If you know a thing or two about tiling, you can testify that plywood is one of the worst substrates you can tile over.

Plywood, unlike cement board or concrete slab, moves a lot. Plywood expands and contracts when exposed to moisture. Tiles don’t do well on such a surface.

Unlike the liquid RedGard, this mat features uncoupling capabilities. That is, it absorbs the movements of plywood, ensuring the tile above doesn’t experience any stress that may cause it to crack or fall off.

Besides the above, Custom Building, the manufacturer of RedGard, recommends this uncoupling mat as the ideal solution for challenging substrates such as plywood and wood floors.

As if that’s not enough, RedGard uncoupling mat waterproofs and vapor proofs the plywood keeping it safe from water damage. It’s excellent for tile installation and easy to install.

While we are on installation, the manufacturer recommends you use modified thinset mortar. The mat has a fleece layer that facilitates a stronger bond with mortar. Also, you don’t need to use fasteners with this option.

Suppose you want to tile over plywood and want the project to last long. Go for the RedGard uncoupling mat. It is perfect for the above scenario.

How to Make RedGard Adhere to Plywood?

Both two types of RedGard adhere well to plywood. As for the liquid option, you only need to paint over the plywood and give it time to cure.

As for the RedGard uncoupling mat, lay it down with a modified thinset mortar. Give it time to bond, and then you can tile over it. Before applying RedGard, always clean the surface of the plywood for maximum adhesion.

Does RedGard Increase the Thickness of the Plywood Floor or Wall?

When installing a membrane over plywood, it’s essential to be mindful of the increase in thickness. Whether it’s a floor or a wall, you should know that both RedGard products do not add a significant amount of thickness.

If you are installing the mat, the increase in thickness will only be ¼”. If it’s the liquid membrane, it will be negligible and unnoticeable. The thickness post-installation shouldn’t be a cause for concern.


RedGard vs Cement Backer Board

There are two methods one can use when installing tiles over plywood. One, you can use RedGard, preferably the uncoupling mat, to absorb the stress in the plywood and prevent it from spreading to the tiles.

Or, you can install a cement board over the plywood and proceed to tile installation. Both options have their pros and cons.

A cement board is undeniably the best substrate for tiles. Installing a cement board over a plywood floor is more expensive because you will need to purchase these boards and install them using screws and thinset mortar.

Even though adding a cement board over plywood improves the strength of the substrate and ensures the tiles last longer. RedGard provides a shorter and more cost-effective method of tiling over plywood.

If you have doubts that RedGard won’t uncouple the plywood and tiles, you can go for the cement backer board. But be prepared for a more expensive, tedious, and time-consuming project.

Should RedGard Be Used on Plywood Walls or Floors?

Plywood is a versatile construction material. It can be used on the walls or as a subfloor. So, where should you use RedGard? Does it work best on plywood floors or walls?

From an expert point of view, here is how you should use RedGard. The liquid RedGard works best on plywood walls. The mat, on the other hand, is ideal for plywood floors. The floor experiences more traffic and carries a lot of weight.

Also, if it’s in a shower setting, the floor experiences the highest exposure to water. The RedGard uncoupling mat will withstand all the above better than the liquid RedGard membrane.

Is Thinset Safe for Use on Plywood?

Regarding the installation of the RedGard uncoupling mat, the manufacturer recommends that you use a modified thinset. Considering wood is generally absorbent, is it safe to use thinset on plywood?

Thinset is mandatory in ensuring the RedGard mat sticks to the plywood. However, in this application, it is highly recommended that you use a quality latex thinset mortar.

Why latex? It reduces water absorption for the substrate. Also, it offers better adhesion and strength. If you must install RedGard over plywood, ensure that you use a modified latex thinset.

Is RedGard Good at Waterproofing Plywood?

One of the primary uses of RedGard is to waterproof a surface. The good news is that it can also be used to waterproof plywood. However, you need to know the following.

Plywood isn’t a suitable substrate for high-moisture areas. Even though RedGard will offer some waterproofing benefits, you must understand that wood is susceptible to water damage.

If your shower walls or floor is made of plywood, it’s in your best interests to replace it with cement board. In the long run, even if you waterproof plywood with RedGard, it will get wet and deteriorate.

It’s safer and better to replace the plywood with cement board as early as now. In case there is no direct exposure to moisture, there is no need to waterproof the plywood with RedGard.

Besides Plywood, What Else Can RedGard Be Used Over?

RedGard, both the liquid membrane and uncoupling mat, are versatile. They can be used on a wide range of substrates besides plywood.

Examples include concrete slabs, cement backer boards, and exterior decks. The liquid RedGard can even be painted on metal.

If you have another substrate that requires waterproofing and cracks prevention for tiles, you can consider RedGard.

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