Do You Have To Waterproof Cement Boards?

Most cement boards aren’t fully waterproof, however they are highly water-resistant.

Waterproofing cement boards is a good idea to ensure their long-term durability and to prevent leaks from forming.

is cement board waterproof

What Could Happen If Cement Board Isn’t Waterproofed?

Cement isn’t completely resistant to water. Therefore, it can slowly be penetrated by moisture from its surroundings…though this does take a long time.

Usually the problem isn’t in the boards themselves; it’s in the materials surrounding them.

The reason is that water can pass through the cement boards, which can cause damp issues in walls and ceilings.

cement board in shower

Thankfully that cement is impervious to rotting and mold growth but the same isn’t true of plasterboard, ceiling panels, wooden frames and insulation foam when it gets damp.

The ideal solution to avoid excess moisture problems is to waterproof the cement boards.

Do Durock Cement Boards Need Waterproofing?

Durock cement boards are strong and water-durable.

This makes them a good choice for a tile base.

However, they’re not impervious to water and moisture.

So, if you choose to use Durock cement boards as an underlayer, you’ll need to apply a waterproof membrane first.

some cement boards

Do I Have to Waterproof Hardie Cement Boards?

Not all Hardie cement boards are waterproof.

Thus, depending on the board type you get, you can determine whether or not you need to do any waterproofing.

If you want to save time on the waterproofing part, you use one of their pre-treated boards, such as the HardieBacker cement board which has hydro-defense technology.

These boards are designed to have internal waterproofing treatments.

So, you won’t need to add any membrane or moisture barrier to it.

If you use a non-waterproofed board make sure you apply a waterproof membrane.

Can You Shower With Just a Cement Board?

You certainly can use a shower with cement boards without waterproofing them first, but it’s not a good idea for the long term.

If you plan to tile over the cement board then it is a good idea to avoid the use of soap, oils, and creams when showering.

These products will make it difficult to properly bond tiles to the cement board.

cement board

How Do You Waterproof Cement Boards? 

If you like doing your own DIY projects and you’re thinking of waterproofing those cement boards yourself, here’s an overview of what products to use and how to do it:


  1. The recommended sealant for your cement boards
  2. A waterproofing and crack prevention liquid membrane
  3. A membrane fiber roll
  4. A paintbrush or roller
  5. A pair of thick gloves


  1. Put on gloves to protect your hands.
  2. Apply the sealant to any holes, then run your finger over it to secure it in place.
  3. Next, remove any excess product, and wait till it dries completely.
  4. Don’t use silicone instead of the recommended sealant because it can prevent the tiles from sticking properly on the cement boards.
  5. With your paintbrush, paint the liquid membrane over all the seams and holes on the cement boards. Do this in small sections to ensure even coverage.
  6. After painting each section, apply a piece of fiber membrane over it and press it with your hand to make sure there are no air pockets.
  7. Apply another coat of the liquid membrane over the fiber.
  8. Wait for the first coat to dry, and then apply another one.
  9. You can apply up to three coats of liquid membrane for better protection.
  10. Once you’re sure the painted membrane has thoroughly dried, it’s time to lay down the tiles.


Installing and waterproofing cement boards is an essential step in the construction process. They especially come in handy in areas prone to moisture or constant water exposure.

Therefore, the answer to “do you have to waterproof cement boards?” is that proper proofing of the cement boards ensures your walls and floors will last a long time.

Now that you know all about the benefits of waterproofing and how to do it yourself, water damage problems can be a thing of the past!

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