Laying porcelain stoneware on the floor: advice from a specialist tiler

Recommendation points

• Adhesive selection
• Floor preparation
• Cutting and processing of porcelain stoneware
• What are the features of styling
• Alignment methods

Laying porcelain stoneware seems to be one of the most difficult types of tile cladding. This article is a small educational program in which we will consider working with porcelain stoneware in a comprehensive manner, starting from the correct choice of glue and ending with methods for cutting and leveling such a massive, durable tile.

Porcelain stoneware is mainly a large-format finishing material made by powder pressing and sintering at high temperatures. Such tiles have practically zero water absorption and very high hardness. These advantages are compensated for by a number of disadvantages, of which the most significant is the complex laying technology.

Adhesive selection

The main reason for the peeling of porcelain stoneware from the floor is the aforementioned low water absorption, due to which the glue cannot penetrate deeply into the structure of the material. The matter is complicated by the fact that the back surface of the tile is heterogeneous; a thin loose layer of powder adhered during baking and dense ceramic dust formed during wet factory cutting remains on it. This layer is saturated with glue quickly enough, but because of the same fast polymerization, it does not have time to fix to the whole..

Experienced craftsmen claim that it makes no sense to lay porcelain stoneware on a cement mortar, since it simply does not stick to dense material. In fairness, it should be noted that the use of cement mortar according to official specifications is allowed, but only indoors. In addition, there are enough examples of works where porcelain stoneware tiles adhere perfectly to cement and sand alone. And yet, when working with expensive porcelain stoneware, it makes no sense to save on glue mixture, unless only for environmental reasons.

Definitely, the glue hardening process should be extremely slow and uniform, with low water separation during drying. It is optimal for the glue to finally set within 24 hours and retain its plasticity several hours after preparation. You can only use glue with elastic polymers marked “for porcelain stoneware” and “for floor tiles”. Proven examples of such mixtures include:

• Ceresit CM 19 and CM 16 for formats less than 30×30 cm;
• Perfekta “Hardfix Porcelain Stoneware”;
• Knauf Flex for tiles no more than 30×30 cm.

For luxury designer tiles, use dispersion adhesive (sold diluted) or the Lugato series of porcelain stoneware mixes and similar.

Floor preparation

In most cases, the adhesion of the adhesive to the floor is satisfactory, but it is better to prepare the surface. It is not recommended to lay porcelain stoneware on “floating” substrates: the floor must be hard, smooth and durable, it is optimal to fill in a cement screed.

Traces of building materials, paint should be removed from the surface and the top dusty layer should be removed. The most common problem is the high hygroscopicity of the floor, due to which the adhesive loses moisture too quickly and does not have time to complete the hydration. The issue is resolved by penetrating priming of the floor until the moment when it almost ceases to absorb moisture.

Cutting and processing of porcelain stoneware

Porcelain stoneware is one of the hardest building materials. Unlike clay tiles, it has an almost homogeneous structure, which complicates the cutting process: the edge should be perfectly flat right away, it should not be processed manually.

For cutting porcelain stoneware, you can use special hand-held tile cutters, but such a tool can only be found in professional series and at an appropriate price. A good electric tile cutting machine with water supply will cost at least half the price, on which, although not without effort, it is quite successfully possible to cut porcelain stoneware in large volumes and at different angles.

A good machine alone is not enough, the discs must also be of high quality. Chips can appear both due to the uneven thickness of the diamond coating layer and due to the separation of large fragments from it.

There is also one nuance related to the adjustment of the machine. When sawing, the blade should touch the porcelain stoneware only at the point of sawing; on the return stroke there should be a small gap between it and the edge of the tile. Most often, the problem can be solved by slightly tilting the guide rail, the thickness of the cut will increase slightly.

As for the holes and cutouts in porcelain stoneware, they are made in the same ways as in the tile. The most effective, as always, are diamond tools: strings and bits. Also, porcelain stoneware can be drilled with a spear-shaped drill for tiles, but you should not use tongs and nippers.

What are the features of styling

Even a tiler with minimal experience can handle the installation of porcelain stoneware, but with a certain skill. Before work, the tile must be prepared: peel off the back surface with a metal brush to remove adhering dust.

For laying, use a comb with a pitch corresponding to the tile format, starting from 10 mm for tiles less than 30×30 cm. The glue is applied first to the floor, stretched and passed under the comb in exactly one direction. You can apply only adhesive for laying one tile at a time, otherwise the mixture will dry out on top and lose adhesion.

The adhesive is also applied to the tiles. First, a small amount of the mixture is carefully rubbed into the back surface with a flat trowel, then the glue is pulled out with a comb that is half the size used on the floor.

In total, the thickness of the adhesive should not exceed 5–7 mm, optimally 4 mm. As for whether porcelain stoneware should be soaked: it is absolutely pointless, it almost does not absorb water.

Alignment methods

When working with porcelain stoneware, it is very convenient to use holders with suction cups to be able to lift heavy tiles if they are too heaped up.

Real difficulties can arise only when stacking large formats, when the large weight of dense material makes itself felt. This may require the help of an assistant and a second set of holders. Very often, the tile noticeably floats on the glue, crushing it with its weight, especially if the floor has flat drops, uneven shrinkage appears. You cannot make the glue thicker, otherwise it simply will not stick to porcelain stoneware, but there are other methods.

If heavy porcelain stoneware is laid with joints, then it is preferable to use tile leveling systems. Due to the traditionally large size, not many piece SVPs are required, at the same time, the floor will be guaranteed perfectly flat.

For seamless installation, a different method is used. Four self-tapping screws in plastic corks are driven into the floor at the corners of the tiles to be laid. Their height is adjusted by scrolling even before glue is applied, leveling the tiles in the common plane of the floor. The method is quite laborious, but otherwise thick and heavy porcelain stoneware cannot be placed exactly.

Additional precautions are necessary because porcelain stoneware generally has no edging and is virtually free from geometry distortion. Because of this, even the smallest defects on the floor will hopelessly ruin it, so it is better to take the work with all responsibility and scrupulousness..