Lay ceramic or porcelain floor tiles on a timber floor

Fit a rigid board over timber floorboards, then lay and grout ceramic or porcelain tiles for a level, hard-wearing floor.

TF-01Clear the room and check the floorRemove furniture, rugs and any old floor covering down to bare floorboards. Walk the whole floor and screw down any boards that move or squeak. If the floor flexes a lot underfoot, tiles will crack later, so sort loose or bouncy boards now rather than tiling over the problem.

1 box · Timber floor screws (4.0 x 50mm)

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TF-02Fit a rigid backer board over the floorboardsTimber floors move too much to tile straight onto boards, so screw down a rigid layer first: 15mm WBP plywood or 6mm cement/fibre backer board, staggered joints, 3mm gaps between sheets. Screw at roughly 150mm centres into the joists below, not just into the floorboards, using screws long enough to bite the joist by at least 20mm.

8 each · Cement backer board (1200 x 600 x 6mm)

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1 box · Backer board screws (self-tapping, 40mm)

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TF-03Check for pipes and cables before you screw downPipes and cables can run under a timber floor in places you wouldn't expect, especially near sockets, radiators and stairs. Use a cable and pipe detector along your screw lines, but treat it as a guide, not a guarantee, since deep or metal-clad services can hide from cheap detectors. Before you start, find your stopcock (usually under the kitchen sink) and check it turns freely, so you can shut the water off fast if you hit a pipe. If you have any doubt at all, isolate the circuit at the consumer unit before drilling near known cable runs.

1 each · Cable and pipe detector

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TF-04Plan your tile layoutDry-lay a row of tiles across the room with 3mm spacers to see how the last row lands at each wall — avoid finishing with a sliver under 50mm wide. Find the centre point of the room, snap chalk lines through it, and check they're square with a spirit level. Adjust the starting point so cuts are even and balanced on both sides.

1 each · Chalk line

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1 bag of 100 · Tile spacers (3mm)

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TF-05Mix and spread flexible tile adhesiveUse a flexible adhesive rated for timber substrates, not a standard cement-based one, since the floor still moves slightly even with the backer board. Mix small batches and spread with a notched trowel over about 1m² at a time, combing in one direction. Working in small sections stops the adhesive skinning over before you place tiles.

3 bag · Flexible tile adhesive (20kg bag, for timber floors)

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1 each · Notched adhesive trowel

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TF-06Lay the full tilesPress each tile into the adhesive with a slight twist, using spacers to keep joints even. Check level and flatness across each row with a spirit level as you go, tapping down any high tiles with a rubber mallet before the adhesive sets. Leave a gap of about 5–10mm around the room's edges for the floor to move — this gets hidden by skirting or trim later.

1 m² · Porcelain or ceramic floor tiles

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1 each · Rubber mallet

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TF-07Cut and fit edge tilesMeasure each gap individually rather than assuming they're all the same, since walls are rarely perfectly straight. Mark and cut tiles with a tile cutter for straight lines, or a wet saw for notches around pipes and door frames. Wear eye protection when cutting, and dry-fit each piece before gluing it down.

1 day hire · Tile cutter or wet tile saw hire

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1 pair · Safety glasses

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TF-08Leave the adhesive to cureLeave the floor untouched for at least 24 hours, or longer if the adhesive packaging says so. Don't walk on the tiles or grout them early, since disturbing them before the adhesive sets can crack the bond and cause hollow tiles later.

TF-09Grout the jointsUse a flexible grout suited to timber floors, pushing it into the joints diagonally with a rubber float. Work in small areas and wipe off excess with a damp sponge before it hardens on the tile surface. Leave the perimeter expansion gap ungrouted — fill that with flexible sealant instead once the grout has cured.

1 bag · Flexible grout (5kg, for timber floors)

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1 each · Grout float

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1 each · Sponge and bucket

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TF-10Seal the edges and finish offOnce the grout has fully cured (check the packaging, usually 24–48 hours), run flexible sealant into the perimeter expansion gap instead of grout, so the floor can still move slightly. Refit skirting boards or fit a scotia trim to cover the gap neatly, then give the tiles a final clean with a damp cloth. Ventilate the room while adhesive, grout and sealant fumes clear.

1 tube · Flexible silicone sealant

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1 length · Scotia or edge trim

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