Using plywood behind wall tiles

[Matt Beard]

I have seen plywood used in a number of bathrooms in place of plasterboard when the wall is going to be tiled.

Is this a good idea?

What are the pros and cons?

[BigWallop]

Marine Ply, yes. Ordinary Ply, no. Plasterboard is more flimsy than Plywood panels, and therefore more prone to movement, especially if it gets damp. Plywood of the same thickness, or even slightly thinner, is more rigid, but only if it is waterproof treated. Both ordinary Ply and Plasterboard will hold water in the same way, so that's why you would use marine Ply.

The other thing that Ply does better than Plasterboard, is when you drill and fix things to the wall. Plasterboard has a tendency to break away unless proper fixing techniques are used, and that usually means big holes in the tiles to accommodate the fixing. Plywood, on the other hand, only needs a small hole in the tile to allow a normal screw nail to get a grip on the wood behind the tiles.

Cost wise, the Marine Ply is better for fixing, flatter and more rigid, but is more expensive. Plasterboard is cheaper to install, but then you have the disadvantage of having more expensive fixings, and it also has the property of moving and swelling more than the timber backing.

The choice is yours mate. :-)

[Ali Mac]

Pros Very rigid, robust in potentially damp conditions especially if you use marine ply, working with wood

Cons More expensive, working with wood

The cement board, Aqua panel stuff is good and completely rot proof. Wish I'd used it more in my cellar bathroom on the one damp wall.

Alistair

[Grunff]

This has been covered many, many times - there's no need for marine ply, and when most people say 'marine ply' they don't mean marine ply.

WBP (weather & boil proof) ply is perfectly suited to this task. It costs around £20-£25/sheet (3/4"). Marine ply starts at around £80/sheet.

[Vaci]

I lined my shower cubicle with Aquapanels, and found them very quick and easy to work with, and formed a very sturdy surface. The only slight caveat is that the panels are stiff and brittle, so they are not forgiving if your fixing surface is a bit out of true - they will crack rather than bend.

Vaci

[Christian McArdle]

Yes.

When WBP ply gets wet, it cares very little. When plasterboard gets wet, it turns to the same consistency as semi-digested baby food.

Cons? It's more expensive. 20 quid a sheet, instead of a fiver.

What's just as important is tiling technique. You should forget any idea of dot-n-dabbing tiles for a shower. Ensure you use a full bed of an adhesive recommended for commercial swimming pools. Check occassionally to ensure

100% contact. Use a similarly high quality grout and seal it with Lithofin KF StainStop. Do that, and your tiles will remain in place for a hundred years.

Christian.

[Tom]

replying to Christian McArdle, Tom wrote: I?m a bathroom fitter. Ply, no matter the quality expands and contracts with temperature change and will cause grout to crack. Moisture resistant plasterboard or tile backer board doesn?t and is cheaper, marine ply is something handymen fit thinking there doing the right thing, but I?ve lost count of how many insurance jobs I?ve done removing it.