Ply lining bathroom floor after lifting floor boards

[Dukie1977]

The floor I am going to tile has pretty uneven and tatty floor boards so I plan to lift them,

Do I need to replace the boards before lining the floor with ply or can I use a thicker ply and screw the ply directly on the joists?

I also plan to install electric under tile heating and am worried that the thickness of the floor boards + ply + backer boars + adhesive + tiles is going to leave me ducking to avoid the lamp shade.

Any advice would be apreciated.

Rich

 

[alternativetiles]

You should overlay with ply, which I know seems daft but you really do need to repair the floor boards first then overlay with ply or an alternative product. It is partly the layers that give the floor it's rigidity. I know of lots of people who just lay a thick floor of ply (18mm thick) and go straight on top though but it's not technically correct.

Sorry to be ambiguous

 

[gcol]

The correct thing to do would be to remove the boards and replace with 25mm WBP. Noggins should be fitted under the edges of the sheets for support. This way you don't have a height issue.

 

[Richard C]

Use WPB ply as suggested; I removed the old boards & laid 22mm WPB directly onto the joists with the edges down the centre of the joists; width was 2.2m so no noggins within the floor area were needed & I couldn’t see much point in putting them in along the 2 wall edges as one was behind the bath & the other would have virtually no weight on it. Use a high quality trade flexible & waterproof adhesive/grout not the budget DIY stuff; it’s a lot more expensive but worth it to reduce the chances of future cracks. The UF heating will add around 5mm or so & most recommend you bed the heater mat in self levelling compound but if you do this, make sure you level the joists under the new floor (mine was around 10mm down in the centre) or the or you could end up with the compound in one large puddle! Mines been down around 9 months now & no problems so far.