Both glazed ceramic and quarry tiles can be laid directly over a concrete floor, as long as it is both sound and dry. They can also be laid on to a suspended timber floor, but only if it is strong enough to support the not-inconsiderable extra weight (it is advisable to check this with a building surveyor). In this case, cover the floorboards with exterior-grade plywood, screwed down or secured with annular nails (spiral flooring nails) to prevent it front lilting; this will provide a stable and level base for the riles.
You will need specially formulated adhesive for laying glazed ceramic floor tiles – this should be a waterproof type in bathrooms and a flexible type if you are tiling on a suspended floor. Lay quarry and terracotta tiles on mortar over a solid concrete floor, or in thick-bed tile adhesive over plywood.
You should lift old floor coverings before laying ceramic or quarry tiles, but, if a solid floor is covered with well-bonded vinyl or cork tiles, you can leave these in place. Remove any wax polish used on them, then tile over them using tile adhesive.
Setting out a tiled floor
Like a tiled wall, a tiled floor needs careful setting-out if the end result is to look neat and professional. This is especially important with glazed ceramic and quarry riles, and patterned vinyl and lino tiles, but matters rather less with plain vinyl or cork tiles where the finished effect is of uniform colour and the joins between the tiles are virtually invisible.
The necessary setting-out is, fortunately, much easier with floor tiles than it is with wall tiles, as you can dry-lay the tiles on the floor surface and move them around until you find a starting point that gives the best arrangement, with cut border tiles of approximately equal size used all around the perimeter of the room.
Laying Ceramic Floor Tiles
- Pin (tack) tiling guides to the floor in the corner of the room at right-angles to each other, then spread some adhesive on the floor using a notched-edge trowel.
- Place the first rile in the angle between the tiling guides, butting it tightly against them and pressing it down firmly into the adhesive bed.
- As you lay the tiles, use tile spacers to ensure even gaps between them. Use a straight edge to check that all the tiles are horizontal and level.
- Start by finding the centre point of the floor, by linking the mid-points of opposite pairs of walls with string lines. Dry-lay rows of tiles out towards the walls in each direction, remembering to allow for the joint thickness is appropriate, to see how many whole tiles will fit in and to check whether this starting point results in over-narrow border tiles or awkward cuts against obstacles. Move the rows slightly to improve the fit if necessary, then mark the string lines using a pencil. Begin tiling in the corner of the room furthest from the door.
- To on border tiles, lay a whole tile overlie the last whole tile laid, hurt another against the skirting (baseboard) and iwatk its edge on the tile beneath.
- Cut the tile and use the exposed part of the sandwiched tile in step 4 to fill the border gap. Use the oft cut to fill the next border gap if it is wider than the gap.
- Use a squeegee to spread grout over the tiles and fill all the join lines. Wipe excess adhesive from the surface of the tiles with a damp cloth.
- Use a piece of wooden dowel or a similar rounded implement to smooth the grout lines. Finally, polish the tile surface with a clean, dry cloth.
LAYING QUARRY TILES
- Add a third tiling guide to form a bay that is 4 tiles wide. Put down a thin mortar bed and place the first row of tiles, using a tiling gauge to space them.
- Complete 4 rows of 14 tiles, then check that they are completely level. Tamp down any that are proud, and lift and re-bed any that are lying lower than the other tiles.
- Complete the first bay, then remove the third tiling guide and reposition it another 4 tile widths away. Fill the second hay with mortar and tamp it down.
- Complete the second bay in the same 5 and use way as the first. If you are installing a tiled up-stand, place 6. Mix up a fairly dry mortar mix. Continue in this fashion this next, aligning individual units with the sritlthmsded brush to work it well into the across the room until you have laid all the floor tiling, then cut and /I t the border tiles.
Remember to take off and shorten rt iota doors before laying floor tiles, and to remove sufficient depth to allow the door to clear both the plywood underlay (if used) and the new tiles.