Boarding over wonky floowboards...

I am about to cork tile my bathroom but the floor board surface is in poor condition (curled up edges due to CH drying and also past plumbing work). Following getting them screwed down properly etc I need to board out to provide a smooth flat surface to tile on to. The dimensions are approx 2x2m.

In the past I have used hardboard (on top of chipboard) but I think plywood might be better in this application.

I have a few questions:

1) What's an appropriate thickness for the board, I want it to be thick enough to disguise the board imperfections (under constant footfall) but not so thick to loose too much of the skirting (which I'd rather not refit) and introduce significant level differences with the landing.

2) I have heard talk of wetting down the boards to get them to shrink a little following fitting ... does this work / is this necessary, as plywood has long grain running both ways which might the effect minimal?

3) Are expansion gaps necessary around the edge (again the plywood should be reasonably dimensionally stable)? If so what is a suitable size?

Any other tips/info would be greatly appreciated.

TIA,

Alex.

Reply to
AlexW
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3/16", with the outer grain parallel to the existing boards.

Tiny, 1/8" or 3mm. What are you covering the gaps with?

I have wondered about using 1/8" (3mm) cork sheets in 2'x3' (600mmx900mm) size for a cork floor. Unfortunately, these are about £3.50 a go. You might need about 10 sheets. It might look nicer than the "normal" size.

Reply to
Chris Bacon

And just to add to Chris' reply - for a bathroom you should get the waterproof grade ("WBP"): that's one of the main benefits of using ply over hardboard in this application.

David

Reply to
Lobster

OK. What's the logic behind 'llel grains then?

OK. Again, what's the logic behind this then?

The comment was applicable to the ply. My intention was to tile over the gaps (assuming less than say 5mm) with some flexible filler in the gaps as the edges will not be subjected to any great load. I did this (small gap though) in my last house on in two bathrooms and it worked fine (though these were chipboard floors ... latest house is 100+ years older and the floors are much less dimensionally stable).

I'll have a think about that one. Cost is not my prime concern (at c. £40) ... getting the right result is more important.

Cheers

Alex

Reply to
AlexW

Will do. Being a ply punter ... is this synonymous with "marine" ply?

Cheers.

Reply to
AlexW

Look at the thicknesses of each "layer" - there will most likely be 3 "layers", one thick in the middle, two thin facings - the thick layer goes at 90 degrees to the boards, so is less likely to splinter.

It's plywood - the layers are bonded at 90 degrees - if you wet it, then the timber in each "layer" expands much more across the grain, hardly at all along it. The facings will crinkle and become unstuck (WBP has been referred to, which is more resistant) - wetting is no advantage, unlike for paper, or hardboard.

I thought you were referring to the ply, in fact...

Let us know how it turns out if you use larger sheets.. you can see them in model shops, rolled up like little carpets...

Reply to
Chris Bacon

Will do.

One more thing, if I can trouble you further...

I was planning to screw the ply down at intevals at the same width as and centered to the existing boards across the width of the boards. Replicating the same intervals along the length seems a bit like overkill ... what do you think is a reasonable spacing?

TIA,

Alex.

Reply to
AlexW

Hmm... I'd probably use 6" centres. It might be necessary to miss some out, e.g. to avoid pulling the ply sharply down into a hollow, which would show on the finished surface. If you can use a belt sander, or even a surform, to rub off any really bad ridges/height differences between the boards that will help. I hope your electric screwdriver is a good one!

Reply to
Chris Bacon

Looks like "square" pattern is not overkill then. Belt sander and drill driver are ready to go (DD should be OK, but its had a bit of stick though!).

Cheers for the advice,

Alex.

Reply to
AlexW

I've glued 6mm ply sheets onto waterproof chipboard. Whether this is suitable for you I don't know.

Reply to
Mike

Didn't use larger sheets in the end, as I thought it would only really look right with a "broken bond" effect (personal taste I guess) and the area I was tiling was so small that the effect would be lost in it with such large tiles.

I also thought that getting the profiles in the bathroom (curved front bath + sink & loo) precise might be a little trickier with the bigger tile & the broken bond etc.

... maybe next time though, when I get a larger bathroom.

Ta for the help,

Alex

Reply to
AlexW

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