Can epoxies be applied over tiles?
One common question you hear in the epoxy field no matter where you come from is – “can I coat over tiles?”
Tiles were, and still are, a popular flooring choice. Their durability is typically great and the right tile can really look fantastic. However, chipping/cracking and slip resistance are not their strong points and grout lines are probably their biggest weakness in a number of ways.
Because of this, some people want a change from their existing tiled floor, however they realise that to remove the tiles is typically a big job that can be costly and time consuming. There can also be other reasons for not wanting to remove the tiles, eg having to raise the floor level again by 10 – 15mm afterwards. Many of these people see a decorative seamless floor and think, “wouldn’t it be great if I could just apply it over the top of the tiles!?”
So back to the question, can you overcoat tiles?…
The fundamental answer is yes, but there are some conditions and additional thoughts you should consider before jumping in.
Here are the questions I ask when someone comes to me and wants to overcoat tiles -
Are the tiles glazed?
Yes - then you need to remove the glaze. You can look to micro-etch with an acid-based etcher, but in my experience the adhesion can be inconsistent with this kind of preparation. Hence, I suggest mechanically grinding to remove the glaze. It’s always hard to achieve 100% removal, but that is not always necessary to achieve strong levels of adhesion.
No – is there a sealer on the tiles? Lots of terracotta tiles aren’t glazed but tilers can apply a sealer to prevent the tiles from looking dirty or showing a spill. If the tile is sealed then you are back to grinding as you are not likely to get good mechanical penetration of the resins into the tile. A lot of sealers also have hydrophobic properties whereby they repel water or any other product trying to penetrate the surface, which obviously makes the task of gaining strong adhesion even more difficult. If the tiles are not glazed and not sealed, then you can clean them (and grout lines) and look to overcoat.
Are the tiles level/flat?
Yes – then look to clean and overcoat.
No – then you may choose to grind flat or apply a levelling compound. The levelling compound could be cementitious or epoxy based.
Are the tiles “drummy” or cracked? Has the grout line cracked?
You need to inspect and test every tile to figure out if it is well bonded. Tapping it with a screwdriver handle or a small hammer can usually reveal if the tiles are loose. Any “drummy” tiles should be removed and the space filled with a levelling product. Cracked grout lines may also need to be removed and a levelling compound applied in its place to fill in the gaps/re-level.
With those substrate-related questions out of the way, here are some other things you need to consider -
What finish are you after – smooth or textured?
If you want a smooth finish then levelling will need to be of a high standard. You can’t have any grout line “ghosting” (ie showing through – see picture above) or it will be visible in the final finish. If the final appearance is textured then it may still be necessary to re-level if the texture profile is smaller than the grout profile.
Do you want to see the grout lines or not?
It sounds like the answer would be obvious, but not always. Showing the tiles can look ok and can actually be the desired look for some.
Additional advice that I recommend you pass on to the floor owner -
- You can’t control if the tiles start to shatter, crack or delaminate when you’re preparing the surface. If it does, there will be a point where it becomes cheaper to remove the tiles and start from concrete rather than overcoat.
- You can’t control if a tile that was not “drummy” becomes loose and causes a failure of your coating sometime down the track.
Both of the points above suggest that removal of the tiles might very well be the best option in a lot of cases.
Note – In the photo above, you can see a great looking decorative epoxy floor done over tiles. In that instance you can’t feel the grout lines when you run your finger over the surface but you can certainly see where grout lines were. In this case the client was happy with the result as he did not seek a flat finish to start with.
Take care and talk to you later,