How to fix floor tiles onto different surfaces

Time spent on proper preparation makes the fixing easier, quicker and ensures a better finish.

TILING ONTO CONCRETE

New concrete must be at least six weeks old and thoroughly dry before fixing ceramic floor tiles. The surface must be smooth, flat and free from dirt and grease. Uneven surfaces can be improved with leveling compound.

TILING ONTO ANHYDRITE SCREEDS

The screed must be : 
– Allowed to dry out and prepared as per the screed manufacturers recommendations (generally anhydrite screeds should be allowed to dry at a rate of 1 day per millimetre of screed thickness for screeds of up to 40mm thickness and 2 days per millimetre for any additional thickness over 40mm to achieve a moisture content of no greater than 1% w/w or 75% Relative Humidity (RH), however the screed manufacturers should be consulted for their recommendations.

– Free from all surface contamination, dust and laitance (the surface should be lightly sanded and vacuumed).

– Primed using progressively stronger coats of Norcros Prime Bond. Initially apply a 1: 4 parts water dilution and when dry follow with a 1: 3 dilution applied to the first coat. If after these 2 coats the surface is still absorbent, apply a further coat at a 1: 2 dilution and allow to dry.

TILING ONTO WOODEN FLOORS

Existing wooden floors must be rigid, stable and capable of supporting additional load without flexing and have sufficient ventilation beneath them. There are two basic alternative methods to follow:-

Overlay the existing timber with 18mm exterior grade plywood, which has been sealed. Fully screw down the plywood at 300mm intervals ensuring all junctions are supported by noggings or joists. Use a flexible adhesive.

Overlay the existing timber with special plastic sheeting and use a flexible adhesive.

A flexible grout is recommended with all of these methods. There are many factors to consider when deciding which method is best suited for your particular circumstances. It is important to seek professional advice.

TILING ONTO VINYL TILES

Existing vinyl tiles must be free of grease, polish etc., and firmly adhered to the sub floor. The surface of the vinyl tile must be primed and allowed to dry before spreading the adhesive. Also an additive may be used with the adhesive.

TILING ONTO EXISTING QUARRIES, GLAZED AND UNGLAZED TILES

Existing tiles must be clean, grease free and firmly adhered to the sub floor. An additive should be used with the adhesive and grout when tiling onto glazed tiles.

SETTING OUT

Planning ahead pays dividends, so spend time on the following:-

Laying ceramic floor tiles will raise the level of the finished floor, so if possible remove all fixtures before tiling. Mark a chalk line on the floor down the centre of the room parallel to the most suitable wall (normally this is achieved by viewing the room from the doorway). Lay the tiles down this line and then work towards the wall you think is best, leaving a joint between the tiles of at least 3mm. Tile spacers can be used to achieve a uniform size joint. Avoid small cuts, as they can be difficult to cut and do not look professional.

CUTTING TILES

Floor tiles are generally harder to cut than wall tiles. Modern tools make the cutting of most types of ceramic tiles simple.

ADHESIVES

Working and drying times vary according to the weather, but the following should give you an idea of what to expect:

Rapid Set floor adhesive has a working time of approximately 30 minutes and can be walked on after about 6 hours.

Normal Set floor adhesive has a working time of approximately 2 hours and can be walked on after about 24 hours.

Mix the adhesive as per manufacturers instructions and spread with a solid bed trowel onto the surface to be tiled. Lay each tile into the adhesive firmly with a slight twisting motion to ensure a solid bed and prevent voids under the tile. Remove surplus adhesive from the tile surface with a damp sponge or cloth. Work in small areas of a about 1 sq. metre at a time so that tiles are fixed before the surface forms a skin. Every so often use a spirit level or straight edge to check that the tiles fixed are flat. Remove and adjust the amount of adhesive to achieve a flat surface, but don’t leave it too late or the adhesive will set.

Leave floor to set before grouting (usually 24 hours unless using a rapid set adhesive).

In bathrooms, special attention should be paid to sealing the gap between wall and base, particularly where the location is on a suspended floor.

An additive should be used with the adhesive when fixing fully vitrified tiles such as porcelain.

GROUTING

Do not begin grouting or walk on the floor tiles until the adhesive has fully set and can be walked on. Force the grout into the joints using a spreader. Remove surplus grout from the surface with a squeegee and sponge, then peg the joints with a rounded stick to achieve an even better finish. Note:- when grouting tiles on a timber floor, use a water-based polymer admixture to improve flexibility.

MOVEMENT JOINTS

These joints are 6/8mm wide and filled with a flexible filler, which allow for movement and prevent tile damage. They are normally installed where flooring abuts wall, steps, columns etc., on large floor areas and over structural movement joints. Floors less than 4 metres between walls will not normally need movement joints.

MAINTENANCE

With proper care and attention, a correctly installed, good quality ceramic floor tile should give many years trouble-free service. Grit is the biggest enemy of any floor material and a mat well adjacent to external doors is strongly recommended.

Some terracotta and slate tiles may need re-sealing.

Most tiles consist of the BASE CLAY and the SURFACE GLAZE. 

The BASE CLAY determines the frost resistance.

RED CLAY should be FROST RESISTANT down to minus 5^o C. 
WHITE CLAY should be FROST RESISTANT down to minus 10^o C. White clay also tends to cut better. 
PORCELAIN is totally FROST PROOF

The GLAZE determines the DURABILITY of the tile, and obviously the ANTI-SLIP PROPERTIES.

GRADES OF WEAR are set according to European Standards – PEI grades. 
Grade 1 is a wall tile. Not suitable for a any floors. 
Grade 2 is suitable for LIGHT TRAFFIC ONLY – e.g. Bathrooms 
Grade 3 is suitable for MOST DOMESTIC uses – e.g. Kitchen, Conservatory, but not the MAIN ENTRANCE. 
Grade 4 is suitable for ALL DOMESTIC and MEDIUM COMMERCIAL use - e.g. Most shops & showrooms 
Grade 5 is for ALL DOMESTIC & COMMERCIAL uses. Put them anywhere! Take-aways in particular.

There are also grades of SLIP RESISTANCE, but this can normally be determined just by feel.

The THICKNESS of a tile has nothing to do with how long lasting it may be and only affects the strength of the actual tile. I.e. A thin tile will require a first class fitting job, since any areas without the correct adhesive contact can easily break. With thick tiles, you can afford to be less exact.