Stick ceramic tiles straight onto thinnish plasterboard?

[AL_z]

I'm installing a new bathroom in my house. One of the jobs is to tile the walls adjacent to the bath, as I'm going to install a shower attachment.

One of the walls seems to be made of thin (8mm or 10mm?) plasterboard. On that wall, I'll be fixing a shower attachment holder. Is it OK to stick the tiles directly onto the plasterboard? Or should I face the plasterboard with say chipboard first, to increase the rigidity and strength?

Also, should I use a special waterproof adhesive and waterproof grout with the tiles, or is the regular stuff considered OK for shower areas?

The tiles I bought are 300 x 250mm granite effect tiles which are almost twice as thick as the average small 150mm square wall tiles. So they do have a lot of rigidity and strength of theor own.

Thanks...

Al

[NT]

if you dont mind them popping off en masse

waterproof for sure, and if you just use green chip then adhesive that can handle flexing. Sounds like the sort of installation I dont like though.

even more vulnerable to board flexing then.

With crappy boarding like that it may be lightweight framing as well, so you might want to remove the PB and sort the thing out properly.

NT

[Phil L]

Any wall that is likely to have much moisture on it, IE in a sower enclosure or over a bath, needs to be boarded with aquapanel. Microscopic holes in the grout allow water to penetrate into plasterboard which very quickly disintegrate, regardless of which adhesive/grout you use

[Phil L]

Any wall that is likely to have much moisture on it, IE in a sower enclosure or over a bath, needs to be boarded with aquapanel. Microscopic holes in the grout allow water to penetrate into plasterboard which very quickly disintegrate, regardless of which adhesive/grout you use

[AL_z]

harry wrote in news: [e-mail]:

Thanks to everyone for the replies. After considering the products and methods suggested, I'm now thinking of using WBP or similar, fixed over the existing studwork, (a) because I can srew into it (when fixing the shower head holder and the hinged shower panel. It would also give extra rigidity to the cheapo studwork. The wall in question is 5ft wide by 7ft tall. Just to be safe, I am thinking of painting the WBP with soma kind of waterproof paint, as I gather that WBP ply is not 100% waterproof - especially the surface ply which I gather isn't primed, as supplied. I have a spare tin of exterior masonry paint. Would that do? Or should I fork out for a bitumen- based tanking paint? Will tile adhesive stick to this? Can anyone recommend a truly waterproof and slightly flexible tile adhesive?

Al.

[Jules Richardson]

That doesn't sound very thick, given that it's a shower wall that might get bumped by elbows; I'd go with the thickest wall you can get in there (it's preferable to go with one piece; fixing one thin layer to another won't be as rigid as just going with one thick layer in the first place - but I appreciate that you might not want to rip the wall down :-)

This side of the pond they do a cement backer-board for tiling onto (often branded as wonderboard) - I'm not sure what the equivalent is in the UK. Some moisture will get through the tiles, so it's better not to use chipboard as the backing - plus the bond between tile and wood isn't always as strong as tile and cement, and you don't want tiles falling off in a few years (probably).

The cement stuff's more expensive than chipboard here, but still less than equivalent thickness of ply.

Hmm, not sure. You might be OK with regular stuff and some grout/tile sealer, but personally for a high-moisure area like a bathroom I think I'd just use the waterproof stuff to be sure.

I'm not sure it makes much difference; it's still essentially a lever if put onto a less-than-rigid surface, and any flex at all could weaken the bond or cause grout lines to fail.

cheers

Jules

[stuart noble]

I wouldn't go overboard on the waterproofing. The tiles/grout are normally sufficient because the water is running off too fast to allow penetration. It's the joint with the shower tray that causes problems, and using silicone instead of tile adhesive for the bottom row is one solution.

[AL_z]

Jules Richardson wrote in news:i29jv4$ve2$ [e-mail]:

Thanks - I was looking at 12mm cement board today in our Travis Perkins store. It's fairly expensive, Agreed, it's probably the most reliable option as far as staying inflexible and flat, long term, and least likely to be degraded by dampness. However, I guess it'll be a bit iffy trying to screw onto it, so I'm thinking of using WBP 18mm ply (exterior grade ply). Perhaps not quite as reliable long-term, but more screwable-into..

Al

[AL_z]

stuart noble wrote in news:8vY1o.9599$FM1.1635 @hurricane:

That's an idea. I have some fancy plastic angled strip that fits unter the bottom row of tiles that nicely seals the gap between the bath and the tiles. Not sure how to deal with the corner though, as the stuff won't go round corners! I will figure something out.

Al

[NT]

5

If you mean interior corner, ie around the bath, just cut the strip at

45 degrees.

NT

[The Natural Philosopher]

You can most certainly tile straight onto 12mm/15mm plasterboarrd if its reasonably well studded. The tiles stiffen it up no end, and its the standard way for builders to do it.

NO preparation needed with one caveat, If your tiles have places water can collet and you get grout flex and cracking, you will get water behind. Not good. My way to tackle this is to use silicone on the BARE PLASTERBOARD wherever there is a possible point of flexure, where it meets a basin, bath edge or shower tray, and then tile OVER that. So if water gets behind the silcone will stop it there.

12mm MDF or even 15mm MDF is superb fior tiling: I use it to box in anything. Or chipboard, but as with plasterboard these too need to be thought about to prevent water getting to it. All the above swell enough to blow tiles off if they get wet. Grouted tiles are more than enough for splashes, but not for puddles. Use silcione behind tiles if there is a potential nastuy corner.

This has led to the mistaken assumption that you therefore need waterproof crap behind tiles. This is bullshit. You dont. TILES ARE WATERPROOF and GROUT IS HIGHLY WATER RESISTANT.You need it if you cant seal reliably and tile and grout properly. Its amateur bodgery and muddled thinking.

[The Natural Philosopher]

No. it doesn't. It traps water UNDER itself and draws it up by capillary action, and IMHO it looks SHITE. And is responsible for people thinking they need waterproof backing.

Use silicone to seal the units to the plasterboard BEFORE tiling. That totally avoids the ugly and prone to mould silicone grouting. Just grout to the bath or shower tray. You may get hairline cracks, but they go nowhere and because the grout is slightly permeable THEY DRY OUT.

Not sure how to deal with the corner though, as the stuff won't go

Yep, its a total amateurish bodge strip.

[Jim K]

so when you seal your bath to the untiled wall with silicone and then attempt to stick tiles to the silicone (which won;t stick to the silicone of course) - what stops water creeping up behind your bottom tile row by the same capillary action, soaking the pboard and ending up with the same net result?

Cheers Jim K

[Jules Richardson]

You can get special screws for attaching to the sub-surface (it still needs bonding too, but you use screws as well to keep it all rigid). The screws are self-starters, but they also have ridges on the underside of the screw head so that they bed into the cement, rather than sticking out slightly proud as a normal screw would (which would make tiling over them harder). A box of 100 over here works out to about 4 quid (and I think I paid around the equivalent of 12 quid for 4x8' 1/4" cement board sheets).

As for screwing things on later, once the tiling's done, a regular drill will drill a pilot hole through the cement board easily; far easier than drilling through tile. It's sturdy stuff, but it drills nicely (and cuts pretty easily enough with a stanley knife - needs about three heavy scores with a good blade, then it just snaps right along the scored line)

I'm not sure you'd need to go with 12mm; whatever 1/4" works out to in mm will probably do, so long as you're retaining the plasterboard wall beneath (1/2" cement board is significantly more expensive than 1/4" over here).

cheers

Jules

[The Natural Philosopher]

if you must go with cement board, it takes rawlplugs etc very well indeed. FAR better than plaster board. But *tiled* plasterboard itself works very well for light duty stuff, like e.g. a soap dish, mirror, cabinet or toilet roll holder. In essence you attach to the TILES and the tile cement spreads the load to what's behind it,..