Tiling on to hardwall

[Delosdos]

Hi, I'm hoping someone here can help me out with some bathroom tiling related queries!

A couple of months ago I stripped off the tiles in our bathroom. As the tiles came down they pulled off a lot of the backing plaster and revealed the bricks/thermal blocks underneath. As the bathroom was tiled from floor to ceiling on all four sides this left a bit of an ugly, bumpy mess. To patch things up I PVA'd the wall and slapped on a layer of hardwall. Now, after sorting out the plumbing I've got to the stage where I'd like to put up the new tiles. The tiles are quite chunky, 30cm x 60cm x 0.9cm, and weigh about 22kg per square meter.

I've bought some Bal SBR and originally I had hope to get away with coating the hardwall with the SBR and tiling on to that. However, after doing lots of research online it sounds like tiling over hardwall with or without the SBR as a primer is a big no-no. Is this correct?

Unfortunately we don't have enough room to board over the walls. The bathroom is tiny and I've already had to chase the bath 2cm in to the wall. If I put aquaboards up I'd be encasing the bath in place, which just sounds messy.

I am now thinking about putting on a skim of multifinish, and then putting the SBR on top of that. Question is - does this sound like a sensible idea? The tile weight is slightly over the 20kg per square meter recommendation for gypsum plaster, but i'm hoping I can get away with it. At least, it sounds preferable to the alternative of tiling over the hardwall at any rate.

Anyway ideas/pointers would be massively appreciated!

Many thanks!

 

[Old Mod]

As u know your already on limit with 22Kg for your tile, however, cement based adhesive when mixed can weigh 1.4-1.7kg/m2 per mm thickness. That's gonna tip u way over.

 

[Delosdos]

Thanks for the reply - and yes, good point. Hmm, as I say, boarding isn't really an option for us, but can you think of any options for us to get the wall ready for tiling? Could I skim the hardwall with something else that's going to make it a bit tougher?

 

[Ian]

Any chance of a couple of pictures please? It may help us suggest a few options.

 

[Delosdos]

Hi, sure here you go - it's a bit rubbish as I took it on my phone, but all the walls are pretty much like this. It's a small room, only 1.7m x 2.2m

 

[destroyer2813]

You wanna be covering those pipes before you fill those chases in as well

 

[White Room]

If your going to patch up with an undercoat plaster you should kill any suction as you did with pva but Thistle bonding would have been the base coat to use not Hardwall.

 

[Delosdos]

Yes, since taking that photo a couple of days ago, I insulated the shower pipes and skimmed over them

Our house was built in the 1930's and we bought it a couple of years ago, most of the plaster in the other rooms disintegrated as we stripped off the wall paper so we've more or less re-plastered the entire house now. I've always used hardwall for jobs like this in the rest of the house, prior to skimming with multifinish and it's done a good job. I assumed it would be perfectly adequate for the bathroom too, but it seems like it might not be. If I didn't use hardwall, it sounds like sand + cement render would have been better for tiling on from what i've heard, but it's too late for that now unfortunately

Anyone got any suggestions on what could be done to give the tiles the best possible chance of sticking to the wall for as long as can reasonably be expected?

Cheers

 

[Delosdos]

Ok, minor update - I think i've reluctantly decided to scrape off the hardwall & board over instead. Not much fun and a hard pill to swallow, but if it gets the job done properly then it's probably going to be worth spending a couple of days hard work on it