How To Apply RedGard Over Durock? (Explained)

For those who may have never used RedGard, this liquid waterproofing material made by Custom Building Products cures into a monolithic membrane. RedGard is one of the most popular waterproofing materials because it is effective and very easy to install.

RedGard can be applied on a wide range of substrates. Today, we will be focusing on how you can apply RedGard over Durock. We will also share some professional tips to ensure your project is successful and stress-free.

Durock cement board
“Maggie’s bathtub” by madgerly, Flickr is licensed under CC BY 2.0

What is Durock?

Before we can share our guide on applying RedGard over Durock, it is crucial that we introduce what Durock is and also touch on whether such a surface must be waterproofed.

Durock is one of the strongest tile bases. It is a water-durable cement board that can be used on floors, tubs, walls, showers, and exterior surfaces.

Durock is mold resistant, and when this feature is paired up with water durability, that makes Durock the best cement board for wet areas.

It’s non-combustible and also very easy to install. USG, the manufacturer, recommends that Durock be installed with tile backer screws.

There are plenty of reasons why you should consider Durock cement boards. It’s lightweight and pretty strong. That means it’s more resistant to cracking, deformation, and denting.

If installed correctly, Durock can last for up to two decades. The other thing that will be of interest to you is the water resistance features of Durock.

No matter how much water is exposed to Durock, it won’t swell or decay, nor will it facilitate mold growth. In simple terms, Durock is not vulnerable to water damage. Considering this last feature, should you waterproof Durock?

Is It Necessary to RedGard Over Durock?

RedGard is a waterproofing product, and Durock is resistant to water exposure. Considering these features, you may wonder why Durock should be waterproofed.

For instance, if you are installing Durock in a shower or bathtub, why do you need to apply a layer of RedGard?

Well, there are a couple of reasons why you should waterproof Durock with RedGard. Durock is a waterproof substrate. It won’t deteriorate when exposed to water. But the materials behind it will.

Durock cement board will allow water to soak and pass through it. Because of these reasons, you need to waterproof the surface with a material such as RedGard.

Since most people prefer to use Durock in wet areas, RedGard will act as a barrier preventing moisture from passing through the Durock and affecting other components within your structure.

Undoubtedly, Durock is water resistant, but other things in your wall will rot when frequently exposed to moisture.

Applying a waterproofing material may seem like more work, but it will ensure your project lasts for longer without experiencing the effects of water damage. Therefore, it’s necessary for you to RedGard over Durock.

A Guide on How to Apply RedGard Over Durock

Now that you know the features of Durock and why it’s necessary to waterproof such a surface, here is an in-depth guide to applying RedGard over a Durock cement board.

Step 1 – Gather Equipment Needed

To RedGard over Durock, you will need a few supplies such as the RedGard itself, a brush, roller, painter’s tape, a pair of gloves, and a respirator. You will also need a waterproofing membrane and a drop cloth.

Step 2 – Surface Preparation

Most people often jump into applying the RedGard directly. But that’s not recommended. You should ensure the surface of the Durock is clean, smooth, and level. If there are any defects, they should be repaired before application.

Step 3 – Application

Once you have prepared the surface, you can lay RedGard over the Durock. Start with the seams. They are the most delicate part. Use a brush since it offers more precision on the seams and corners.

Make sure that you apply a uniform thickness. What you have to know about RedGard is that when it’s pink, it’s still wet. It turns red when it dries. You need to keep this in mind during the application.

A pro tip when applying RedGard over Durock is always to use a roller on the flat areas. This will make the application much easier and faster. This will be the first coat.

Step 4 – Install the Waterproofing Membrane Fabric

To ensure the Durock walls are 100% waterproof, you should install the waterproofing membrane fabric to the seams. Before moving on to the next step, ensure that all seams are covered with a waterproofing membrane.

If left unattended, the seams can act as entry points for moisture. You can prevent that from happening by using the waterproofing membrane fabric.

Step 5 – Add a Second Coat of RedGard Over Durock

RedGard has a fast-drying formula. Therefore, within two hours, the paint would have dried. You can know this by checking the color of the finish. If it’s red, then the first coat has dried.

In this second coat, you should paint everything, including the Durock and the membrane fabric covering the seams.

Give it time to dry, and the RedGard will waterproof the Durock. Some people often go for an extra third coat. But that’s optional.

Step 6 – Install Tiles on the Painted Durock

Both Durock and RedGard can be tiled over. This doesn’t have to be a cause for concern. However, any tiling on the RedGard and Durock should be done after three days.

Even if you are in a hurry, you will have to wait for the RedGard to fully cure over Durock. If you rush the project, the tiles may not stick, or the waterproof barrier could be weakened. Make sure that you give it enough time.

That wraps up our guide on how to apply RedGard over Durock. As you can see, it’s relatively straightforward, even though it’s a bit laborious and time-consuming.

If you want to work much faster, you can ask for an extra set of hands. A family member or friend could help you get the job done more quickly. But ensure you fill them with the correct method of waterproofing Durock with RedGard.

Professional Tips for Applying RedGard Over Durock

The above guide should be sufficient for you to lay RedGard over Durock. However, there are additional tips that can ensure this project is done successfully. These tips include;

RedGard should be applied when the room temperatures are around 40 degrees F. This is the best temperature for RedGard to cure over Durock. This temperature must remain constant for the three days RedGard will take to dry over Durock.

RedGard bonds very well over Durock. However, to get the best results, apply two or three coats of RedGard. One coat isn’t often very sufficient. Do not paint too many coats. Ensure the thickness isn’t more than 125 mils.

RedGard contains some ingredients that can be harmful when inhaled or ingested. Therefore, it’s crucial to wear protective clothing when applying it to Durock. A respirator and some gloves are mandatory. If you are working on a room within your home, ensure it is closed and inaccessible to children who may touch the waterproofing material.

Besides a roller brush, you can apply RedGard with a trowel or an airless sprayer. The airless sprayer requires some technique. Otherwise, the application will be pretty messy. If you are a newbie, it’s best to keep off the sprayer. A roller brush is the best and easiest tool to use. You can use a brush on the corners and seams.

Remember that RedGard cures within an hour or two, depending on the temperatures. If it’s extremely cold or humid, you need to give it more than six hours to dry. It’s very easy to tell that RedGard has dried over Durock because it will turn from pink to red.

When assembling materials for the RedGard application over Durock, you should consider how much you will use. That will depend on the size of the room you want to waterproof. A gallon of RedGard can cover 55 ft² of space. Do the math and calculate how much RedGard you will need.

Cleaning Up After Applying RedGard Over Durock

There will be a mess after you have painted RedGard over Durock. It’s inevitable, no matter how careful you are.

It will help if you lay a drop cloth over the tub to avoid that. That will prevent the number of spills you have to clean up after.

Secondly, you should safely clean the tools used. We would strongly advise against washing your brush in the sink.

It’s better to do it on a bucket of water and then safely dispose of the remnants. It’s not a good idea to pour waterproofing materials down your drain.

Also, RedGard dries fast. If you leave RedGard on tools for more than two hours, cleaning them will be hard. Clean your tools as soon as you are done with the application.

If RedGard stains dry on a surface, you can peel it off. But for more effectiveness, you can use a scraper. It’s important to be gentle when using a scraper as it can damage the tub or tiles.

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