Kerdi membrane is a waterproof pliable sheet that is made by Schluter, a leading manufacturer of construction materials. This waterproofing membrane is often used with tiles in wet areas such as bathrooms or steam showers.
If you’re planning to use Kerdi membrane on the floor of your residential or commercial property, below is a comprehensive guide that’ll be discussing all you may need to know.
That includes the benefits of using a Kerdi membrane on the floor, an installation guide, tips, and much more.
Can You Use Kerdi Membrane on the Floor?
Kerdi membrane can be used on floors. That’s its main purpose. Being a waterproofing membrane, Kerdi is designed to prevent the entry of water past floor substrates.
As mentioned earlier, the Kerdi membrane is used in the installation of tile and stone on floors. You lay the Kerdi membrane first and then tile or stone over it and you’ll have a watertight setup.
Please note that the Kerdi membrane is used on floors that will be exposed to moisture or water. A good example is a bathroom floor.
So, there is no need to use it in your living room or bedroom floors because there is no need for a waterproofing membrane in these rooms.
Be as it may, with the Kerdi membrane on your floor, you will enjoy peace of mind knowing that your structure is protected from water damage.
What Type of Floors Can You Use Kerdi Membrane On?
Some floors are incompatible with the Kerdi membrane. To avoid unwanted scenarios, here is a list of the type of floors that you can use Kerdi membrane on. These are the sub-floors recommended by Schluter.
1. Cement Backer Board – We can all agree that the cement backer board is one of the best subfloor materials. It’s strong, durable, and versatile. It’s also the go-to floor substrate for tile installation.
The good news is that the Kerdi membrane is 100% compatible with a floor that is made out of cement backer board.
2. Plywood Floors – Not many people know this, but plywood floors can also accommodate the Kerdi membrane. A Kerdi membrane is even more useful in a plywood subfloor because it’s more vulnerable to water damage.
When installing Kerdi membrane over plywood floors, it’s crucial to ensure the plywood is sturdy enough.
3. Concrete Floor – Lastly, if your floors are made out of concrete, a layer of Kerdi membrane can prevent water from seeping through.
Even though concrete is water resistant, too much water can affect the integrity of the entire floor. To prevent such, you can waterproof your concrete floor with a Kerdi membrane.
What are the Benefits of Using Kerdi Membrane on a Floor?
Now that you know Kerdi membrane can be used on floors and the type of floors it is compatible with, let us explore some of the benefits of using this pliable sheet on a floor;
• It waterproofs your floors – This is the main advantage of using Kerdi membrane on a floor. By not letting water pass through, a Kerdi membrane can prevent water damage from happening to the floor and the materials surrounding it.
With Kerdi membrane on your floors, you’ll enjoy peace of mind knowing that your floor is adequately protected from water damage.
• It prevents cracking of tiles – The other reason people use Kerdi membrane is because it prevents the transfer of lateral movements from the floor to the tiles. Thus, preventing the cracking of tiles.
• It inhibits mold development – It goes without saying. Wherever there is moisture, you’ll most likely find mold.
With a waterproof barrier like Kerdi membrane on your floor, mold will be the last thing that you’ll come across in your shower or bathtub. So, in some ways, the Kerdi membrane on floors keeps you safe.
• It is compatible with many types of floors – Kerdi membrane can be used over plywood, concrete, and cement backer boards. On top of it, you can lay tile or stone. It comes with some element of versatility that most homeowners appreciate.
• Kerdi membrane can serve you for years – What I love most about this waterproofing sheet is that it can last for decades, irrespective of the traffic and load-bearing weight it is exposed to. As long as you install it correctly, the Kerdi membrane will last for a long time.
How to Install Kerdi Membrane on the Floor?
The process of installing the Kerdi membrane on the floor is no different than doing it on the walls. However, if you’ve never done it before, do not worry, we’ve prepared a detailed installation guide for you.
Step 1: Prepare the Floor
You just can’t start laying the Kerdi membrane directly on the floor. Things such as dirt and contaminants have to be cleaned.
Failure to do so can result in poor adhesion between the Kerdi membrane and the subfloor. Apart from cleaning, always inspect the condition of the floor and make necessary repairs.
Step 2: Calculate How Much Kerdi Membrane You’ll Need
With the help of a tape measure, calculate the size of the floor and then cut the Kerdi membrane so that it fits that size.
When cutting the Kerdi membrane, leave some extra inches for the areas it’ll meet the wall or other fixtures. This ensures there is no gap left on the floor surface.
Step 3: Create a Mortar Bed on the Floor
Schluter has their mortar known as Schluter-ALL-SET. You can either use that or an unmodified thinset mortar.
Please stick to these recommendations because if you use another type of mortar, that may lead to Kerdi failure. Create a mortar bed ensuring that it has a uniform thickness.
Step 4: Lay the Kerdi Membrane Over the Mortar Bed
Carefully, install the Kerdi membrane over the mortar bed. Apply some extra force to get rid of air bubbles that may form between the membrane and the mortar bed. You can use a flat trowel to stick the Kerdi membrane to the mortar bed.
Step 5: Overlap the Seams and Cut the Corners
Schluter recommends overlapping the seams by at least two inches and using mortar as an adhesive. As for the corners, cut them carefully so that they transition directly to the wall or any available fixture.
And that’s how easy it is to install the Kerdi membrane on the floor. Give the mortar about 24 hours to fully cure, then you can lay tile over it.
Common Mistakes to Avoid When Installing Kerdi Membrane on the Floor
To ensure you do a perfect installation job, I’m going to share with you some of the mistakes you need to avoid. These are common mistakes most DIY folks do when installing Kerdi membrane on a floor.
• Leaving air bubbles inside between the membrane and mortar bed. These will lead to weak points within your setup and can eventually cause delamination. Always press on the membrane so that it’s directly attached to the mortar bed.
• Poor mortar thickness or coverage. The mortar bed should be uniform all over your floor. Failure to do so will affect the adhesive strength of the mortar.
• Installing the Kerdi membrane on a dirty or contaminated floor. Foreign substances can also affect the adhesive strength of unmodified mortar.
• Using the wrong type of thinset. I was very specific earlier about the type of mortar you should use when installing Kerdi membrane on a floor. Please stick to Schluter ALL SET or unmodified thinset mortar.
Are There Kerdi Membrane Alternatives You Can Use on a Floor?
Kerdi is just one of the many floor waterproofing products on the market. It’s popular because it’s effective at doing its job. But there are other alternatives worth considering.
For instance, we have RedGard which is a liquid waterproofing product. It’s much easier to install than Kerdi membrane because with RedGard all you have to do is paint it with a brush. And you don’t have to worry about corner treatments or seams.
We also have other Kerdi membrane alternatives which boast more unique features like Ardex 8+9, Laticrete Hydro Ban, and TEC HydraFlex.
Before settling for the Kerdi membrane as a waterproofing material for your floors, take the time to explore and compare these alternatives.