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Levelling on a tiled subfloor

  |  Levelling on a tiled subfloor

Levelling on a tiled sub floor

Levelling a tiled subfloor requires having a look at the condition, potential movement & potential moisture issues of the tiled floor.

We understand that there are two main types of tiled sub floors that most contractors come across and will try to deal with these below. Additionally we need to point out that the adhesion of the tiles, as well as surface contamination and potential moisture issues should be taken into account and any advice we offer is based on industry practices and the products that we stock in the UK.


Ceramic Tiles

Theoretically, it is possible to level on top of the tile surface but it is important to consider the potential issues before you start work. If your final floor covering is likely to be a wooden floor then you need to consider the tension created, the sub floor surface and the suitability of the sub floor itself. Whilst it is difficult to gauge the strength of the adhesive bond below the tile, you should look out for hollow spots as a new sub floor created with primers and levelling compound will likely tighten everything below it and could create additional problems.

If you are satisfied that the tiles are suitably strong and well bonded, you must then check for moisture issues in the Joints. Often times this is not an issue but it should be checked. Always keep in mind that the British standard is 65RH or less for all sub floor readings and we would not deviate from this

The next thing to be aware of is the likely contaminates on the surface of the tile and how best to deal with them. All tile surfaces must be cleaned with WAKOL R4515 Tile Cleaner before any other procedures can be carried out. If this is not available, then a degreaser that contains acetone can be used as directed by the manufacturer. Tiles have to be abraded after cleaning to create a better bond. Visible scratches need to be created .We advise the use of diamond discs under a single disc machine for this process. All dust and sanding residue should be vacuumed immediately after.

If there are no moisture issues present, then WAKOL D3045 Gritted Primer can be applied (after the floor has been cleaned as instructed) and left to dry. If moisture readings are above the British standard but below 95% RH, then a moisture suppressant would be advised before the use of WAKOL D3045 Gritted Primer. In this case, we would recommend WAKOL MS330 in one layer or WAKOL PU280 in 2 layers Subsequently, WAKOL Z520 Thin Screed can be installed in a maximum layer of 10mm to create a new sub floor for the adhesion of a new floor covering. This is a quick and easy way to create the perfect sub floor that is suitable for a new installation of wood flooring the next day.


Stone and Quarry tile

This is a slightly different area to ceramics as the product has an absorbent surface. Additionally, it is possible that these types of product are in older buildings with no mechanical DPC. Just as with ceramics, it is important that the contractor assesses the situation for potential moisture issues and structural integrity before any work is carried out.

Once the contractor is satisfied, then the same processes and products can be used with one exception. As the surface is absorbent, it must be cleaned and sanded as described above and WAKOL MS330 or WAKOL PU280 should be applied before the WAKOL D3045 Gritted Primer.



If you need help and advice on something that is not covered, please contact us and we will try our best to answer your questions.