How to lay quarry and terracotta tiles
If you wish to lay quarry or terracotta tiles over a timber floor, then check the depth of the joists before you buy the tiles. Joists less than 125mm will not be strong enough to support the weight of these thick, heavy tiles, and your floor will sag and crack.
A timber floor must be covered with plywood, as with ceramic tiles.
What you'll need
1. Measure one wall and mark its mid point. Mark the same distance along the adjacent wall. If you join these marks with a straightedge, you'll have a guideline at exactly 45 degrees to the walls of the room.
2. Nail the guide batten to the floor along the line, using masonry nails if the floor is concrete. Leave the nail heads proud—they'll be easier to pull out later.
3. Apply a band of tile adhesive a little over one tile wide next to the batten. Press the first row of tiles into it, using spacers to ensure even gaps.
4. Once you've laid the first row, remove the batten. Spread adhesive between the row you've laid and the room corner.
(If the room is very large, you may have to lay these end tiles after you've completed the rest of the whole tiles in the room, and they've had 24 hours to dry.)
5. Lay all the whole tiles, working one row at a time and inserting tile spacers at each joint. In this room, whole tiles stretch from wall to wall leaving half-tile triangles next to the skirting boards. In other rooms, the gaps may be larger than half a tile.
6. As you complete each row, use a batten and a hammer to tamp it down. After every 4 or 5 rows, check the levels with a spirit level. If a tile is too low, prise it up, apply a blob of adhesive to its back and replace it.
Mix up tiles from different boxes before laying them. Quarry tiles have natural colour variations, and a floor looks best if the shades are randomly scattered rather than in concentrated blocks.
Guard against staining
Seal porous terracotta tiles before laying them. This will prevent them becoming stained later on by the grout. Buy a branded sealer, or make up your own by mixing 2 parts of boiled linseed oil to 1 part of white spirit.
Once the tiles are laid and grouted, give them as many additional coats as they can absorb, allowing each to dry before applying the next one. Consult a specialist tile supplier about waxes and other preparations that'll protect the seal and enhance the colour.
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