I'm not so sure about chipboard bathroom floors!

[AL_n]

The house I bought recently has chipoard floors instead of floorboards. It's the first house I've owned with such floors. In most of the rooms, the chiboard isn't a problem, but I'm learning that it was probably not a good choice for the bathroom. I mean, if you cover the floor in lino or vinyl tiles, and then you get a leaky tap connector that starts a little occasional drip, before you know it, the chipboard under the vinyl has become soaked and you've got a big ugly problem. I've finally cured all the little leaks in the bathroom (courtesy of the previous owner's dodgy plumbing skills) and dried the chipboard floor out after removing the vinyl tiles. I will now replace all the tiles, and just hope I don't get any more leaks. My last house had its bathroom downstairs, where the floors were solid. There's a lot to be said for that arrangement!

I was thinking of painting the chipboard with thin varnish or something to make it waterproof, but I fear it would still get soaked, via the joints, and then it would take forever to dry it out, due to the varnish sealer.

Anyone got any ideas/tips/comments on chipboard bathroom floors?

Al

[Gio]

We use the green moisture resistant variety throughout. Why folk fit standard stuff is beyond me. Cost is not that different and it does not swell or crumble. We had some off cuts laying about the garden for years following our self build extension. The children used it for bike ramps etc. The colour faded but the board retained its integrity. No doubt removing and refitting is not something you want to do ? Would the 'Waterseal' type silicone fluid 'proof' your existing boards ? It is thin and searching.

Gio

[The Natural Philosopher]

Only one. The bathroom MUST be puddle free, whatever technology you cover the chip with.

I got mine that way, with tiles, and its just FINE. before I did, it pushed all the tiles off one corner.

I fixed the leak, let it dry, used a thicker layer of flexible cement, and grouted to save my life.

[The Natural Philosopher]

Oh yes it does.

Just marginally slower.

[Gio]

From my experience ours never swelled although I will say it was not sitting in water all the time. The clue may be my reference to 'moisture resistant' and not saying it was waterproof. ;-)

[The Natural Philosopher]

From my experience, mine did, and it was. :-)

Basically an unseen small drip from the loo coupling collected where the tiles sloped very slightly towards he wall. soaked into the grout, through and blew the tiles off.

>

[Gib Bogle]

I will be facing this issue when I finally get to redoing our bathroom, which currently has small ceramic tiles on chipboard. There is only one very small area next to the shower where water has got to the chipboard and caused half a dozen tiles to come adrift. As a temporary measure I made sure it was dry and applied a couple of coats of a low-viscosity two-pot epoxy. My current plan, when we lift all the tiles, is to apply at least two coats of polyurethane to the chipboard before retiling. I know that polyurethane isn't totally waterproof, but I don't think it needs to be. The main thing is not to allow water to lie on the floor.

[The Natural Philosopher]

Or to make the floor TOTALLY waterproof. Tiles are. Silicone is. Grout is NOT...normally.IIRC additives can make it so, though.

One tip is to e.g. seal round edges of shower trays and baths with flexible silicone BEFORE you tile. that avoids the 'slight flex, grout cracks' problem by and large.

[Tim W]

[....]

Chipboard is a rubbish material. It has no virtues other than being cheap. Plywood screwed to the joists is a better floor, even shuttering ply is alright.

Not much help to you I know,

Tim W

[The Natural Philosopher]

Both will swell when wet.As will MDF. Or any wood based product.

Unless you want to go to the level of purely mineral based sub flooring, in which case the problem is likely to end up rotting the joists underneath, instead, the issue of making a semi wet-room inside a wood structure is perfectly simple: Namely at one level or another there needs to be a completely impervious membrane or barrier wherever water may collect.

That could be a waterproof plastic sheet under the tiles or it could be a sealed welded vinyl covering of the floor carried up to the appliances and skirtings, or it could be a well laid tile floor, with any likely crack points sealed with flexible silicone before grouting, and a water proof grout.

That, and sugfficient heat and ventilation, will hold pools till they evaporate.

Anything else is substantially a bodge. If water does collect under a not well laid impervious layer like tiles or vinyl it will cause mould and stink and possibly stain, eve if it doesn't swell what's underneath or rot it.

[stuart noble]

That's an interesting test. I've often wondered how water resistant the green stuff really was. If you've used it as a bike ramp after numerous wet/dry cycles, I'd say it's very different to the standard chipboard, which you can easily put your foot through if it ever gets wet.

Strikes me that if you have a long standing bathroom leak you're probably going to have to replace part of the floor up anyway, whatever it's made of.

[stuart noble]

Well, exactly, so you might as well use green chip, which is probably more water resistant than any of them.

[Tim W]

Well, not exactly. Wood will swell across the grain less than 10% from very dry to very wet, will shrink again when you mend the leak and won't lose it's strength (until rot sets in). Chipboard/mdf will swell to twice their own thickness, lose their structural strength and never be any good again, moisture resistant or not. Quality plywood probably is better than anything but quality costs although even cheap ply is better than chipboard.

Tim W

[stuart noble]

Might be easier to just replace the wet timber/chip/ply rather than waiting for it to dry before you can re-lay the floor. Sounds like you don't have any faith in green chip. My limited experience of it suggests it is virtually waterproof, being of a totally different construction to standard chip.

[The Natural Philosopher]

not really. It's still a wood product.

ANY standing water on ANY wood product will degrade it.

So it doesn't matter really waht you use. ALL have to be waterproofed by something else, properly.

green doesn't fall apart when wet, thats all really. But neither does marine ply etc.

[The Natural Philosopher]

simply let it dry. That's what I did. The green s**te went back to its original size. More or less. Good enough to tile anyway.