Tiling on to hardwall

[delosdos]

Hi all, 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 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 I don't think we have enough room to board over the walls. The bathroom is tiny and I've already had to chase 2cm in to the wall just to get the bath in. If I put boards up too I'd just be encasing the bath in place which sounds messy. I've also considered plastering the walls with finishing plaster, but we'd be over the recommended maximum of 20kg per square meter, coming in around 24-25kg (that's including powder-based tile adhesive).

I'm now left trying to decide what would be the best approach at this stage to take to get the walls ready for tiling. Has anybody got any suggestions? What would you do in this situation? Any ideas/pointers would really be massively appreciated! :)

[Colour Republic]

Dri-Coat is the only undercoat plaster you can tile directly on.

Hmmm it's a tough one as you are quiet a bit over the recommended weight if you do skim first, however they are a guidline only, some plaster skims wouldn't hold 15kg where as other well bonded skim coats will take 25kg+

Ideally you'd take it back to brick and either dot & dab plasterboard or use tile backer boards. It's really up to you to make the call but yes the walls would need skimming first if you don't want to take the walls back to brick.

[delosdos]

Firstly, thank you very much for taking the time to reply.

At the moment I'm thinking of going with the finish coat option, because it's the lesser of two evils, but I suppose i'm uncomfortable with the thought of it being a bit of a gamble.

I thought about using an SDS drill with a chisel bit to remove the hardwall, but as it's a fresh coat I suppose the only thing I'm worried about is the damage I might cause to the mortar between the thermal blocks underneath. It probably wouldn't come off very easily at all unfortunately.

I guess if I don't go back to brick, then I'm really only left with slightly rubbish options as alternatives, doh!

[wine~o]

Get a tile removing bit for the sds, it's got a rake/angle so won't harm the brick......

Then use the cement based board as per the post above..

[delosdos]

Hi Wineo & thanks for the advice.

I think I'm probably going to have to reluctantly get on with scraping off the hardwall and put up some backer boards as suggested. It's hard to swallow after thinking I'd made a lot of progress previously, but I'm a bit of a perfectionist and if i thought i'd done it wrong i know it would bother me. That, and a tile might fall off and knock me out when i'm in the bath ;)

I did a test patch this evening - think it'll be easier than i first thought. I scored 4 deep cuts through the plaster back to the thermal blocks, drenched with a sponge, left for an hour then came back and thankfully it came off relatively easily with only a basic wallpaper scraper. So based on that, I think I'll probably score all the walls right back to the brick then steam them and leave to properly soak in, then come back with the SDS + tile-removing chisel as suggested.

Can I ask which aqua/cement/backer boards you guys would recommend?

Cheers,

Andy

[royaloakcarpentry]

Those weight figures are for guidelines.

Good professional job from start to finish and you would have been ok.

It never ceases to amaze me on bathroom refurbs that the hardest tiles to remove are the ones applied to a background deemed unsuitable by the Tile Traders Association............figure that one out!

[Colour Republic]

It's not the TTA that set the guidelines it's Britsh Standards.

Besides British Gypsum say their backing products with the exception of dri-coat are not suitable

[royaloakcarpentry]

TTA also lists guidelines which you need to adhere to for membership. Whether they copy BS or have slight variations is another matter.

Backing plasters are not suitable, hence why there was no advice for him to do so.

I have ripped out bathrooms constructed in mdf........the tiles aint shifting. Unsuitable substrate.

Ripped out a few ancient bathroms half tiled originally then fulkly tiled over the bottom half and over the distemper on the top half. Not suitable but lasted donkeys years.

OSB is not a suitable tiling background but again a pig to get the tiles off, and the board had no water ingress.

I have ripped out many bathrooms over the years which were done on backgrounds 'not suitable' for tiling which have been buggers to get the tiles off.

Mind you, on the other end of the scale, I have ripped out bathrooms where the substrate was perfect for tiling but the tiles came away with the flick of a finger. The only thing holding them up once the adhesive bond failed was the grout.

Give me the finger flick removal any day lol

[delosdos]

Ok, so here's a quick update :)

I've got the walls back to brick / thermal block. I used an SDS drill with an Armeg tile removing bit. It took about 3.5 hours to do a room of 1.7m x 2.2m. After this, we spent the entire weekend chiselling off rough edges/left over bits off plaster, and brushing down with wire brushes. The plaster was 1-2 years old, and very well bonded to the bricks behind it. If you've got older plaster then I'm sure it'd be much quicker.

Steaming made very little difference, so I wouldn't recommend it. If you're going to have a go at this, know that it's a particularly tiring and extremely dirty job to do. I wouldn't take it on half heartedly, but having said that we are now very happy that we did the work. If your plaster is old it will be considerably easier. If you're unsure, do a small test patch - try to pry off some plaster with a a flat screwdriver, back to brick, and see how easy it is.

If you're not up for lots of work and your plaster isn't blown, then you might be better off skimming with finishing plaster and going to buy lighter tiles instead, which is nothing to be ashamed of :)

Thanks for the advice, and hope this helps others too!