Can You Tile Over Expanding Foam? (Explained)

Tiles offer property owners several benefits. They are aesthetically pleasing, easy to clean, and more durable than certain types of floors such as wood.

Generally, tiles are very picky about the substrates they should be installed on. It’s probably why you are researching whether it’s possible to tile over expanding foam.

Expanding foam has many uses. It’s mainly used to fill holes and cavities on walls. If you plan to tile over a wall with holes filled with expanding foam, here is everything you should know.

expanding foam

Will Tiles Stick to Expanding Foam?

Yes, tiles can stick to expanding foam. Several techniques can be used, such as using plywood between the expanding foam and the tiles.

Or, if the expanding foam is on a small area, the surrounding area can reinforce the tile’s adhesion. Yes, you can make a tile stick over expanding foam. The problem is – will it last?

Will Tiles Last on Expanding Foam?

Tiles don’t last for very long over expanding foam. The thing about tiles is that they are pretty vulnerable to movements. It’s why we are advised to use uncoupling membranes when installing tiles over substrates.

Expanding foam is quite flexible, and this poses a danger to tiles. When expanding foam flexes, these movements will affect the tiles, which can eventually lead to cracking.

The bottom line is that you can make tiles stick to expanding foam, but the longevity of such a project is unpredictable.

How to Install Tiles Over Expanding Foam?

Tiles shouldn’t be installed directly over expanding foam. Doing so is inadvisable, and probably, the results will be short-term.

If you must tile over expanding foam, the best approach is to use plywood or cement board over the expanding foam.

The plywood or cement board sandwiched between the tiles and expanding foam will ensure the tiles have better adhesion and aren’t affected by the flex of expanding foam.

The size of the expanding foam will be a determining factor. Because the plywood will have to be cut according to the size of the expanding foam.

In case you have filled some parts of your wall with expanding foam, fit a cement backer board or plywood in between before laying the tiles.

Should You Remove Expanding Foam Before Tiling?

Expanding foam is often used as a quick fix for filling cavities in walls. As a result, most people prefer to use it from time to time.

However, you may not know that expanding foam can lead to several challenges in the future. This is a relatable example.

If you have some expanding foam on a wall and want to tile over it. Removing the expanding foam is a great idea.

When you remove the foam, you can replace it with a leveling compound that doesn’t flex and won’t crack your tiles.

There being no expanding foam inside the walls, you won’t have to worry about your tiles being exposed to movements.

One of the reasons people avoid removing expanding foam before tiling is that it’s pretty hectic, and that’s why people opt to install some plywood over the expanding foam.

What is the Recommended Tiling Substrate?

Tiling over expanding foam is unconventional, and that’s why the tiles don’t last very long after that. The recommended tiling substrate is a cement board.

On cement board, tiles adhere pretty strongly, and as long as you perform the installation correctly, the tiles can hold up for years without coming off.

The cement board isn’t flexible as expanding foam. Therefore, you can confidently install tiles without worrying about cracking in the future.

Can You Tile on a Small Area with Expanding Foam?

It’s impossible to find a floor or wall comprising only expanding foam. This product, as mentioned earlier, it is used to fill cavities.

In case you have some expanding foam on a small area, this opens up a loophole for tiling over. Provided the amount of expanding foam is minimal and the entire surface is in great shape, you can mortar and tile over.

But you must ensure the expanding foam is cut much deeper to create room for the mortar to get inside the opening.

Therefore, you can turn a blind eye to a small and inconspicuous area and apply expanding foam over it.

How to Fix a Plasterboard for Tiling?

Expanding foam is often used to fill dents on plasterboard. If there were old tiles on your plasterboard and you damaged some during the removal process, you will have to fix the plasterboard before installing new tiles. So, how can you fix the damaged plasterboard?

First, you need to assess the extent of the damage. If the plasterboard is damaged beyond repair, you have no other option but to get rid of the plasterboard and replace it with a new one.

But if the dents are minor, you can fit smaller chunks of plasterboard inside. You can use plasterboard adhesive to fit the smaller bits in place. Only after fixing the damaged plasterboard can you install new tiles.

Can I Use Construction Adhesives to Stick Expanding Foam to the Tile?

Since expanding foam isn’t a typical tiling substrate, you may have to use an adhesive. You will, however, have to be very careful in choosing construction adhesives that will not dissolve expanding foam.

If you use the wrong adhesive, the tiles will eventually fall off. Do we recommend using construction adhesives to stick tiles to expanding foam? Absolutely not.

In the construction industry, it’s advisable always to do everything by the book. For tile installation, use a cement board and thinset mortar as the adhesive.

The moment you start improvising, you are creating a recipe for disaster. Though convenient, installing tiles over expanding foam is not advisable. The chances of the tiles sticking are minimal.

Is Expanding Foam Vulnerable to Moisture Damage?

Tiles are mostly installed in areas that experience a lot of exposure to moisture. Examples include bathrooms and swimming pools.

The downside of installing tiles over expanding foam is that eventually, the expanding foam will deteriorate due to long-term exposure to water or moisture. When that happens, the tiles will most likely fail, which can be a huge setback.

Can an Uncoupling Membrane Assist?

Decoupling membranes come in handy when tiles are installed on a substrate that experiences a lot of lateral stress. Expanding foam is an excellent example of such a substrate.

If you must tile directly over expanding foam, it would be a good idea to consider a decoupling membrane such as DITRA or Laticrete Strata Mat. These membranes will absorb the movement of expanding foam and prevent the cracking of tiles.

What to Do When You Find Expanding Foam Under Your Tiles?

If you have recently moved to a new home and have discovered expanding foam under the tiles, you may be worried about the longevity of the tiles on the surface.

In case the tiles are still intact, you don’t have to worry about them coming off. The installer could have used any of the techniques mentioned above.

Nonetheless, you should always be prepared for the worst-case scenario. Should the tiles fail eventually, you will have no option but to replace them.

How Can You Cover Expanding Foam?

Tiling may seem like an excellent method of covering expanding foam, but it’s surrounded by many complications. If you are looking to cover expanding foam, the best solution would be a paint job.

Unlike tiling, painting is pretty straightforward. You will need to cut and sand the expanding foam. Then paint directly over with several coats.

However, covering expanding foam with tiling is a complicated process. It’s better to go for the easier option.

Is It Worth Tiling Over Expanding Foam?

Professional constructors will heavily discourage tiling over expanding foam because of the many reasons we have shared with you. Tiling over expanding foam is a complicated process surrounded by many uncertainties.

Getting the tiles to stick is easy. But the problem is with longevity. In the long run, tiling over expanding foam isn’t worth your time or effort because a lot has to be done, and the success rate is pretty low.

Instead of risking, it’s better to remove the expanding foam and replace it with a suitable substrate such as a cement board. Or, if the walls have plasterboard, you can repair them and then lay the plaster.

Will Mortar Stick to Expanding Foam?

For most tile installation jobs, the adhesive used is thinset mortar. It’s therefore essential to know whether thinset mortar will stick to expanding foam. Thinset mortar will dry up over expanding foam, but the structure won’t be robust.

To ensure the thinset mortar creates a solid foundation for tiles, you should reinforce it with another material, preferably a fiberglass mesh.

Is Expanding Foam a Suitable Substrate for Tiles?

The only suitable substrate for tiles today is a cement board. Anything else must be customized to enable the tiles to stick and adhere for a long. Expanding foam isn’t even in the top five ideal substrates for tiles.

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