Even the highest quality porcelain tile will not deliver the expected result if the base beneath it does not meet the requirements. Cracks, voids under the tile, delamination a year after installation — all of this is most often the result not of poor material but of an improperly prepared surface. Let us look at what base is needed for porcelain tile and how to prepare it correctly.
Regardless of the surface type — concrete, screed, old tile — the base must meet several key parameters:
Screed is the most common type of base for floor porcelain tiles. There are several options to consider:
Technically yes, provided the old covering is firmly in place with no voids or delamination. Checking is straightforward: tap the tile across the entire surface — a dull sound indicates a void beneath. Those areas must be removed. If the old tile is holding well, the surface is sanded to improve adhesion, primed and then the porcelain tile is laid using a specialist high-adhesion adhesive. The downside of this approach is the increased floor height, which can create a step at the junction with other floor coverings.
Concrete floor slabs are a common base in new-build properties. Here it is important to ensure the concrete is sufficiently cured (at least 28 days after pouring), that the surface has no cracks and is not crumbling. Large cracks are filled with repair compounds, the surface is sanded and primed. If the height differences are significant, a levelling screed is poured. Laying porcelain tile directly on raw concrete without levelling is only possible when the slab is in perfect condition — in practice this is rarely the case.
Plasterboard as a base for porcelain tile is a debated choice. It is used primarily for walls, where it works well provided the sheets are fixed without any flex and the framing is spaced no more than 40 cm apart. Moisture-resistant plasterboard is essential for bathrooms and kitchens. For floors, plasterboard is not suitable — it cannot handle foot traffic and furniture loads, and it deforms and deteriorates when exposed to moisture.
Flatness requirements depend on tile format:
The larger the format, the stricter the requirements. This is worth considering at the tile selection stage — for more on choosing the right porcelain tile for specific conditions, read the article How to Check Porcelain Tile Quality Before Buying.
Priming serves several purposes at once:
For porous bases (aerated concrete, old screed) use a deep-penetration primer. For dense surfaces (concrete, old tile) use a contact primer with quartz filler, which creates a rough texture. Apply the primer in at least one coat, and in difficult cases — two coats.
A wall base for porcelain tile differs from a floor base. The key factors here are rigidity and the absence of any flex. Plastered walls must be completely dry and show no signs of delamination. Check the plaster by tapping: dull-sounding areas must be removed and restored. For walls, surface verticality matters — deviation must not exceed 2 mm per metre. Irregularities are corrected with levelling plaster, after which the surface is primed before installation begins. For guidance on choosing the right porcelain tile depending on whether it is going on the floor or the wall, read the article Wall vs Floor Porcelain Tiles: Key Differences.
A good base is half the battle of a successful installation. A flat, strong, dry and clean surface with correctly applied primer will ensure reliable adhesive bonding and a long service life for the covering. Do not cut corners on preparation — it is the one stage that cannot be corrected once the work is finished. To find the right porcelain tile for specific installation conditions, browse the catalogue at itum.ua — a wide range of materials with full technical specifications and expert advice on selection.