Frequently Asked Questions

Where do tiling jobs go wrong?

The number one cause is failure to follow the adhesive manufacturers' instructions. The manufacturer has spent years finding out the best way to use his product. Surface preparation is essential. Failing to clean the surface properly leaves a weak link in the system. Kitchen grease and bathroom scum have virtually no tensile strength and guarantee a failure. The next most common reason for failure is tiling tight into corners. All buildings suffer some degree of movement, and if the tiling is tight the tiles will develop stress cracks and "blow" off the wall. It is quite possible that the tiles will stay there held by the grout but completely free of the wall. The secret is to leave a gap of about 6mm around the edges of the wall and grout it. The grout is compressible enough to accommodate the movement. You could use silicone sealant, particularly if the area is going to experience a lot of water. 

Now What?

Decide the layout of your tiles. Take all your tiles and shuffle them together, if they are not a mural. The individual boxes (even from the same batch and it pays to check that they all carry the same batch number) may vary slightly in colour, and if they are randomly distributed, this will be far less noticeable.

How many tiles should I buy?

As a general rule area +10% but if you buy from one of the multiples buy an extra pack as you can return it for a refund if it is left over. It is a good idea to keep the unused tiles in your shed or loft, in case you need to replace some. This particularly applies to patterned tiles, which are very prone to changes of fashion. We offer very good discounts if we supply the tiles.

Adhesive

Two main types, Powder which is cement based and is suitable for outdoor use, including swimming pools, and paste which is suitable for indoor walls. Cement based adhesives are *not* suitable for use on plaster. Epoxy adhesives cost the earth and unless you are converting the spare bedroom into a car battery factory can be ignored. If the tile manufacturer's instructions are to soak the tile, while the adhesive manufacturer's are not, do not soak. Modern adhesives control suction much better than the old sand and cement used up to about 1950, when modern adhesives were devised. Their adhesion is something like 50 times greater. Sand/cement fixed tiles can be "pinged off" intact, tiles correctly fixed with modern adhesive will not come off in pieces bigger than 1"sq. Once again, I cannot stress enough how important it is to read the instructions carefully and take heed. If you have any doubts, contact the helpline.

Grout

Again two main types Powder and ready mixed, not my choice, because it often develops shrinkage cracks and can be difficult to clean off. And again I'd avoid epoxy which is for operating theatres and the like. 

Bonding Agent

PVA (polyvinyl acetate) is the most common, usually used at 4:1 dilution and allowed to dry. For really demanding applications more water resistant bonding agents are available. Not strictly necessary but recommended. Bonding agents do not make up for poor surface preparation, but enhance the effect of good surface prep.

How do I prepare the surface?

Walls

Papered strip back to plaster, prime with PVA.

Painted The paint must be well fixed.  Ideally strip back to plaster, but you can simply wash well with sugar soap and abrade with sandpaper before priming. Emulsion paint or limewash are to be removed. They will cause you many tears if you do not strip back to something solid. 

Plaster/plasterboard; The plaster must be sound, and well stuck to the wall behind. Prime with PVA bonding agent diluted 4:1, allow to dry overnight. On highly trowelled surfaces sand before priming. Too much trowelling draws the fine particles to the surface and these tend to compromise the surface cohesion. Again do not use cement- based (powder) adhesives on plaster as in the presence of moisture the two can react with each other to form ettringite which will result in bond failure. While this caveat does not apply to plasterboard, there is no point in using cement-based adhesives, as the substrate is not resistant to water and therefore if there is any water ingress (read my comments about project design) the job will fail. Should you feel it necessary, there are cement-based panels available, but these are no substitute for good design and detailing.

Concrete/render; As for plaster, but cement-based adhesives are suitable. The surface should be cleaned of any mould release oil by mechanical roughening or acid etching if the concrete is cast, and any laitence must be removed. PVA priming recommended, acrylic for any permanently wet areas (not likely in a domestic situation).

Tiled; Abrade with coarse sandpaper, prime with a waterproof primer. Obviously the existing tiles must be well fixed.

Timber Must be reasonably rigid - 1/2" minimum marine ply recommended. PVA bonding agent diluted 4:1 left to dry.

Floors

Concrete Any laitence (the fine material which tends to congregate on the surface of the concrete) must be mechanically removed e.g. by a kango hammer with a toothed blade. If greasy (e.g. a garage) contact an adhesive manufacturer about a suitable degreaser. Prime with PVA 4:1.

Floor boards 12mm (minimum) marine ply screwed down at 140mm centres. Prime with a waterproof primer. This will normally result in a step between rooms, so see below.

What if I have just ripped up my floorboards, and I want tiled floors? Do I have to put down floorboards again?

Get 18mm ply, WBP (Water and Boil Proof) minimum, marine or flooring grade are suitable. If this will cause a step downward, you can obviously source thicker plywood. Paint at least the edges and (soon to be) underside with Cement Particle Board (CPB) sealer paint. Let the paint cure as recommended by the manufacturer. Screw the boards down at 6" (150mm) centres along the joists, with noggins (extra pieces of similar timber nailed or screwed at right angles between the joists) inserted under the joins between the boards, which should then be screwed down to the noggins. Allow a fortnight for the whole job to stabilize. Then use a cement-based thickbed adhesive with a flexibilising polymer additive to fix the tiles.

And finally two rare types of floor, both to my knowledge only found on ground floors and in cellars;

Asphalt; Check it is flooring grade asphalt. It will be *very* hard and brittle, and was often pigmented brown, brick red, or chrome oxide green. Remove all polish, use a waterproof primer, and tile as per concrete floors.

Magnesite; Only likely in old houses (pre about 1920). Normally coloured coral pink or verdigris. A small lump, when held in a gas flame will glow brightly, like a gas mantle, at the edges, whereas asphalt will burn with a smoky flame and a tarry odour (beware, molten asphalt will give a nasty burn if you let it contact you). Magnesite needs complete removal, and replacement with 3:1 sand/cement screed. Allow to cure for a month (put down coconut matting should you wish as a temporary measure) then tile as per concrete. Magnesite was often made with sawdust as a filler, and when the tiling traps any water vapour this rots (turning into fungus), expanding the magnesite and ruining the tiling job.

I have a flat roof outside my window, and I want to make it into a tiled patio what should I do?

Firstly, consult a Structural Engineer that the roof will take the weight of the patio. (see below) then put down 500 gauge building polythene, and on top of this 2" of 3:1 sand cement with weldmesh halfway down. Allow to cure, damping down if necessary in hot weather. PVA in the mix is a good idea. Tile as for an internal concrete floor, but using frost resistant tiles (manufacturers will advise). NOTE: this will not make a leaky flat roof waterproof, in fact I recommend the roof be inspected by a roofer, and if necessary, maintenance carried out prior to the job.