Tiling onto floating floors

Floating floors are those which are not attached to a rigid substrate. Generally this will be a tongued and grooved wooden board above an acoustic or insulation material. They are used to improve floor insulation and/or to reduce noise. Normal wooden floors flex when loaded but this movement is even greater on a floating floor as the boards are not supported by joists.

Common issues and queries you can face



Left image: As a floating floor is not supported by joists, any applied load creates significant movement over a big area. This can be felt as bounce in the floor when it is walked across. As the applied load increases so does the severity of movement. Right image: The edges of a floating floor are even more susceptible to exaggerated movement as they are not supported and any applied load is spread over a smaller area. If the adhesive used to fix the tiles is not flexible or thick enough to absorb the amount of movement, the tiles will either delaminate or crack. Large tiles will exacerbate the deflection across each tile's width.

Unsupported joints

Unsupported joints

If a joint between wooden boards of a floating floor is not correctly located or fixed, it will be susceptible to highly localised movement which will crack the tile along the joint. If the boards of a floating floor are not tongued and grooved, they are not suitable for tiling.



When a floating floor is over-boarded to add rigidity, the extra board has to be securely attached to the original boards. If nails are used, constant movement of the floor can loosen them, press on the underside of the tile and cause cracks. If the screws/nails used are too long they can bottom out on a rigid surface underneath and create a column, over which tiles will crack.

Over-boarded with plywood or tile backer-board

A secure solution is to fix a second board over the existing timber. This increases the rigidity and prevents localised movement. If a water-resistant tile backer-board is used to overboard, it will virtually eliminate any moisture related movement.

  1. Prepare

    Verify that the extra height from the over-boarding can be accommodated and that the floor is capable of supporting the expected load. All tongued and grooved boards should be glued together securely and wedged around the edges until dry.

  2. Fix the over-boarding

    Use WBP grade plywood at least 15mm thick. Prime the back and edges of the plywood with weber PR360. Lay the boards so that the joints do not coincide with joints in the existing timber and leave slight gaps between boards to allow for expansion. Screw the boards at 200 to 300mm. Leave a movement joint around the perimeter for expansion.

  3. Lay tiles

    Fix the tiles into at least a 5mm thick solid bed of weberset pro lite - rapid. Leave joints at least 3mm wide for grouting and make provision for movement.

    Leave the adhesive to set and then grout the tiles with weberjoint wide flex or weberjoint premium. Use weberjoint silicone sealant to fill the perimeter movement joints.

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