A Guide To Choosing The Right Tile Adhesive
Professional tile layer Dmitry Drozdov (@instaburpro) has shared some useful tips on how to choose the right tile adhesive. What should you pay attention to? Why is one adhesive three times more expensive than another? Does the price affect the quality of the product? Read our article to find out!
Please note that we’ll be talking about single-component, cement based, adhesives, since they’re the most commonly used for laying tiles. First of all, you should determine for which specific tasks you need a tile adhesive.
Below, a few things you need to establish before making a purchase:
- What type of tile and size are you working with?
- What substrate are you working on (plaster, drywall, etc.)?
- Do you have a heated floor?
These are all very important factors that will affect your choice of adhesive.
Be careful! Unfortunately, you can’t always trust the information you find on the packaging. If the adhesive says “for tiles of any format” or “for any type of substrate”, you should take that with a grain of salt: it might just be an advertising gimmick. The only thing you can, and should, rely on is the adhesive class.
CLASSIFICATION OF GLUE FOR TILES
According to GOST 56387, ISO 13007/AS4992 CE, and UNI EN 12004, there are three main classes:
- Simple adhesive (class C0);
- Normal adhesive (class C1);
- Improved adhesive (class C2).
Each class meets specific requirements, but it should be noted that, curiously, C0 is only considered to be an adhesive (and classified as such) in Russia, where it is sold according to GOST standards.
Class C0 is an adhesive for tiles with normal water absorption (5% of the tile weight and above). It is only suitable for small or medium-sized ceramics (not for porcelain stoneware by all means), to be installed in a heated indoor environment (no outdoors) but with no underfloor heating system, on a solid mineral substrate (cement plaster). The adhesion to the substrate, also known as the strength of the adhesive bond, for simple adhesive must be at least 0.5 MPa (0.5 N/mm2).
For example, you might use class C0 adhesive for a kitchen backsplash where tile format is no more than 30x30cm or 25x35cm. Only light ceramic tiles on cement plaster! This class is not suitable for working with porcelain stoneware, outdoor environment, a heated floor, tiles larger than 30x30cm, or tiles installed on drywall or hydro insulation materials.
Class C1 can be used on both ceramic tiles and porcelain stoneware. It is suitable for installations on underfloor heating systems, outdoor, in areas of high humidity, on drywall or hydro insulation materials. However, there are some restrictions regarding the size of tiles: you shouldn’t use it for anything larger than 40x40cm on a non-deformable indoor substrate, and anything larger than 30×30 on a heated floor system, on drywall or hydro insulation materials. Outdoor work is only possible with small-format tiles in a basement or on a building facade. Such adhesives are not suitable for decorating entrances. Their adhesion strength must be at least 0.5 mPa (0.5N/mm2).
Class C2 is an improved adhesive for all types of tiles and for almost any type of substrate, including old tiles. Adhesion strength is at least 1 mPa (1 N/mm2). Tiles format can be up to 60x60cm for standard C2.
C2 class adhesives are also classified as S1 or S2, which refers to flexibility:
- S1 – Flexible adhesive;
- S2 – Highly flexible adhesive.
An adhesive with greater flexibility is suitable, for example, for laying tiles on deformable substrates (uncured screeds, wooden floors) or when working with formats larger than 60x60cm.
C2 S1 class adhesives can be used when working indoor with tiles sized 20x80cm, 30x90cm, 60x120cm, and 20x120cm, including heated floors. When laying tiles outdoor it is still a suitable adhesive as long as you’re working with 60x60cm tiles or smaller. You could also use it for large format porcelain tiles such as 100x300cm or 120x240cm but only if installing on strong, good quality plaster.
C2 S2 class adhesive is used for any type of surface with tiles larger than 120cm on both sides. It works great when you need to lay tiles of any format on heated underfloors, plasterboard structures, outdoor terraces or balconies.
Classes C1 or C2 can also be additionally labeled with the letters T, E and F. Let’s look at what this means!
T stands for Thixotropy. A more viscous adhesive with reduced vertical slip used for laying tiles from top to bottom, or wherever tiles are laid on a thicker than a regular layer of adhesive.
E stands for adhesive with Extended open time (30 minutes or more). This is the time during which the tiles can be laid. It is convenient to work with such adhesives during the summer time, since its surface dries up and sets slowly.
F stands for Fast setting adhesive, used at lower temperatures or when you need to get a quick set of adhesive strength.
So let’s recap!
First of all, you should look for the information you need on the packaging according to where you are (for example, “corresponds to GOST 56387”). If there is no such thing, then there is no point in reading further because everything that is written on the package simply does not matter.
Next, look for the classification of the adhesive – (C0, C1 or C2) since this marking shows its purpose and the tasks for which it is suitable.
WHAT SHOULD I PAY ATTENTION TO WHEN COMPARING ADHESIVES FROM DIFFERENT MANUFACTURERS?
You need to understand that an objective comparison of adhesives is only possible within the same class: we only compare C1 to C1, C2 to C2, etc. When we have defined the class, we can move on to compare adhesion strength, an indicator that directly affects how long and how well the tile will hold up. You can call it a guarantor of durability. The more adhesion the better!
Remember to look for solid adhesion data on the back of the package or in the technical sheet, and not for promises on the front of the package. Only then, can you compare the prices!