RedGard On Concrete Floor (Explained)

RedGard waterproofing and crack prevention membrane can be used on a wide range of substrates, including cement boards, drywall, and gypsum. But can you use RedGard to waterproof a concrete floor? Let’s find out.

Concrete floor

Can You Use RedGard on Concrete Floor?

Absolutely. Concrete is one of the most suitable substrates for RedGard application.

When you look at RedGard’s data sheet on Custom Building Products, the manufacturer clearly states that this liquid membrane can be used on concrete masonry. They also go on to list that RedGard adheres well to both lightweight and post-tension concrete.

Therefore, if you have a concrete floor that you would like to waterproof with RedGard, feel free to proceed.

What are the Benefits of Applying RedGard to Concrete Floors?

Before we take you through a quick guide on how to apply RedGard on a concrete floor, let’s look at some of the benefits you may get from using this waterproof membrane over such a substrate.

• It Waterproofs the Surface

Concrete floors generally don’t need to be waterproofed. That’s because concrete is porous, and if water seeps through, it will be directed to the soil beneath.

However, too much exposure to water can cause concrete to lose its structural strength with time. Therefore, if you want your concrete floor to last longer, it’s a good idea to waterproof it with RedGard.

• It Ensures the Longevity of Tiles Installed on a Concrete Floor

The main reason why people apply RedGard over concrete floors is that they want to tile over the substrate. Concrete floors are susceptible to movements. They will expand during summer and shrink in winter. These movements can lead to the cracking of tiles.

However, with a layer of RedGard on the surface, it will act as a crack-prevention membrane that prevents the movements of the concrete floor from being transferred to the tiles, thus preventing cracks.

How Do You Apply RedGard to Concrete Floors?

Because RedGard is a liquid waterproofing membrane, it is very easy to apply it over a concrete floor. Here is a quick guide on how to apply RedGard over a concrete floor.

Step 1: Gather Essential Tools

You will need an adequate amount of RedGard. A gallon of RedGard can cover around 25 sq ft. You will need to calculate how much will be enough for the concrete floor. You will also need an airless paint sprayer. This will make application easy.

Step 2: Prepare the Concrete Floor

To ensure RedGard adheres properly to the concrete floor, you will need to prepare the surface. Start by cleaning it with water to remove any contaminants. Give it time to dry before you can spray the RedGard.

Still, in preparation, you will need to fix any cracks or chips in the concrete. RedGard will last longer on concrete that’s smooth and uniform. Therefore, you may have to install a concrete filler if your floor is excessively damaged.

Step 3: Use an Airless Sprayer to Apply the RedGard

Grab an airless sprayer and start spraying the RedGard over the floor. Spread the liquid membrane all over the surface, ensuring it gets into any holes or cracks.

To ensure the floor is adequately waterproofed, don’t leave any gaps when spraying the RedGard. If there are adjacent walls next to the floor, you should also spray them with RedGard.

Two coats of RedGard are enough to waterproof a concrete floor.

Give it time to dry, and your concrete floor will now be waterproofed.


Do You Need to Dampen a Concrete Floor Before Spraying RedGard Over It?

A pro tip most experts use during RedGard installation is dampening the concrete floor before spraying Redgard over it. Concrete floors are porous. Therefore, when you spray RedGard over dry concrete, it may seep into the floor, and you may use a lot of product.

When the floors are dampened with water, it prevents the RedGard from being over-absorbed by the dry concrete floor. However, when dampening the floor, do not pour a lot of water as it may dilute the RedGard.

Do You Need a Primer When Applying RedGard on Concrete Floors?

A primer can help promote adhesion between RedGard and concrete floors. However, it is not mandatory. RedGard has adequate adhesive strength to attach itself to concrete on its own. Whether you should or shouldn’t use primer is entirely up to you.

Should You Apply RedGard Before Tiling Over a Concrete Floor?

If you have plans for tiling over a concrete floor, you should apply RedGard first. Apart from its waterproofing features, RedGard is also a crack-preventing membrane.

With RedGard in between tiles and the concrete floor, it will prevent the transfer of any lateral movements from the floor to the tile.

Tiling directly over concrete floors is not advisable because there is a high chance that your tiles will crack prematurely. To ensure the longevity of tiles on concrete floors, RedGard can help absorb some movements.

Also, if you live in areas that experience extremely low temperatures, Redgard will prevent water from freezing below tiles.

When water freezes under tiles, it can cause them to pop. But if you live in warmer areas, this doesn’t have to be a cause for concern.

Will RedGard Stick to Worn-out Concrete?

Even though it will stick, RedGard should not be applied over damaged or worn-out concrete. If concrete is damaged, it has to be repaired first before you can RedGard or tile over it.

Otherwise, when you apply RedGard over damaged concrete, tiles won’t adhere well, and they may not last for very long.

As tempting as it may be to want to cover worn-out concrete with tiles, it’s not advisable. However, if there are minor cracks on a concrete floor, you can apply RedGard over it and not have to worry about the structure.

Can You Walk Over RedGard After Applying It on a Concrete Floor?

Once it dries, you can walk over RedGard, and it will hold up just fine. However, during the application, it’s not recommended for you to walk over it as you may pull some off the ground.

When applying Redgard over a concrete floor, that area should be inaccessible for around two hours. Kids and pets can step on it, which may make it a bit ineffective.

Is RedGard the Only Waterproofing Membrane You Can Use on Concrete Floors?

Many contractors and DIY enthusiasts like using RedGard because it’s effortless to apply. However, it is not the only waterproofing membrane you can use on concrete floors. There are many other options, such as Ditra and Laticrete.

Some of these alternatives come in the form of uncoupling mats, which do a really good job in absorbing the movements of a concrete floor and preventing water from passing through.

If you are shopping for a waterproofing membrane, you need to compare RedGard with other options. This will make it easier to find an option that meets your preferences.

What are Other Substrates RedGard Can Stick To?

Besides concrete floors, RedGard can also be applied on drywall, cement boards, gypsum, PVC, metal, and stainless steel.

Therefore, if you have piping over your concrete floor, you can apply RedGard over it. Before applying RedGard over a surface, you should visit their official website and check the manufacturer’s list of approved substrates.

The best part about RedGard is that it is a universal waterproofing membrane that can be applied to plenty of surfaces.

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