Can i lay plywood instead of chipboard or do i need both???

8 May 2009
Reaction score
United Kingdom

I am laying a tiled floor in my bathroom.

Currently there is a chipboard floor layed onto the joistes. The chipboard has had it so needs replacing.

Now can i lay a 18mm plywood straigth onto the joists and then tile, or do i need to lay 13mm chipboard then the 18mm plywood, then tile.

I was hoping to do away with the chipboard so that i eliminate a step into the bathroom.

please email me at [email protected]
Sponsored Links
The best possible thing you can do is to remove the chipboard & replace it with WBP plywood painted with a sealing primer on the back; this is by far the best base for a suspended tiled floor. 18mm is usually sufficient in most cases but if the floor flexes unduly, use 25mm thick, screwed to the joists at 150-200mm centres max. Make sure any joins in the ply run down the centre line of a joist & insert noggins between the joists to support any joins across the joists.

Use only a quality trade, flexible adhesive & grout for the tiles. Most don’t require any surface preparation but check & follow the manufacturer’s instruction regarding this. Read the tiling sticky & the archive tiling posts for more information to avoid you making any mistakes.

It’s not normal to reply to posts via personal E mail. ;)
Ecellent. Thank you.

When you say to seal the underside, do you mean with a PVA glue of some sort.
Sponsored Links
The purpose of priming the underside & edges of the ply is to seal it to avoid any moisture absorption that could cause the plywood to warp, cracking the tiles. You need a waterproof, SBR based sealer such as;

Do not use PVA, its water soluble & totally unsuitable. BAL recommend priming the underside but, in reality, many don’t bother & anything that will act as a barrier to prevent moisture absorption will do it, even old oil based paint.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local