hello. As you can see I'm new here. I'd like your views on whether what I'm going to ask a tiler to do is reasonable.

I'm about to have tiled the lower walls of a downstairs loo which have 15x15 tiles on them already and which have been there since the house was built in the 1950s. On 3 walls the tiling's not pretty but it's sound, almost flat and, most important, I know from taking the same tiles off in the bathroom that they will be a pig to remove and if I start, I'll end up going back to the brieze block and having to completely replaster the walls.

My first question is - is it reasonable to expect a tiler to fix tiles on tiles? The new tiles are to be ceramic, very slim & light, matt finish and 20x25. I was expecting that any minor irregularity in the wall could be compensated for in the adhesive, especially as I've chosen a matt finish to avoid reflections.

The 4th wall is only 1m wide and is a mess. Originally the tiles must have been applied with an enormous dollop of some material straight onto the brieze block and then the tile was pressed onto this. These dollops of material between the brieze block and the tile are about 1/2" deep. In many places this material had blown so I removed it exposing the brieze block (and a 1/2" deep hollow which needs filling). Whre they haven't blown they are rock solid. Where this material is still stuck hard to the brieze block, in some cases the tiles have blown and been removed; in some others they are stuck fast and I know from doing the bathroom that if I start to remove what tiles remain I will end up having to re-plaster that whole wall. The areas which have lost either tiles or tiles+dollops is under 1m squared.

My 2nd question is: is there a way I can create a level and sound surface, filling in the deep hollows somehow? And can I do it without having to wait weeks for plasterwork to dry out?

I'd welcome your views.

I'd be stripping them all off tbh. If it means the render comes off too that's fine. You can then dot and dab plasterboard (12.5mm) onto the brieze block wall to bring it back flush and have a nice flat surface to tile onto

Yep,same as Doug, boarding is a great option because a) you don't have to wait for plaster to dry and b) boards hold more weight.

i'm with the above, it maakes the job a lot quicker and easier for the tiler with little chance of problems arising

Agree with the above comments, and would add that tile over tile on something put up in the 1950's is probably best avoided. Especially if you've experienced probs with blown wall plaster etc and lots of making good when you've been decorating previously. You need a sound base to tile on and I think it sounds like p/board is the best way for you to go. No need to skim, this makes it less sound for tiling, just board and tile.

Wow, Thanks for such prompt replies.

I may not have explained what's there very well for which I apologise.

The problem I had with the bathroom upstairs was imagining I could take off the tiles without too much bother like you would normally. Wrong! The tiles were fixed rock-solid to these dollops of adhesive/cement stuff which were 1/2" deep; and the dollops were fixed like rock to the brieze block; when I chipped at the tile a section of this back material would come off too; I ended up with such a mess of a surface that all the adhesive/cement stuff had to come off which was very hard work and meant I was back to the brieze block!

In this toilet, the tiles are only from floor level up 1.2metres. On this area, just like the bathroom, there is no render. There is only these enormous blobs of some kind of adhesive/cement which is 1/2" thick and holds the tiles in place. That is the only thing between the tiles and the brieze block. From my experience in the bathroom it is rock solid and I will not be able to split tiles off it. Instead it will break away unevenly from the brieze block leaving me with another area which is 1/2" below the rest.

An added problem is that above where the tiles are IS plastered and the finished level is about 2mm below the surface of the tiles. Again from my experience with the bathroom I will end up with a ragged edge into the upper plastered area and have to take off also the 1/2" thick layer of bonding and plaster!

In short if I start to take off tiles on the 3 sound walls I know it will end with me back to the brieze block on every wall and with a complete re-plastering needed to full height. That's something I'd rather avoid if I can.

Does that make any difference to your advice?

It is only the lower half of this one wall of 1 square meter which, in places, is not sound. It's obvious that when the house was built that one wall was re-done for some reason after the rest of the room had been tiled and whatever those enormous dollops of stuff are holding the tiles in place they either have set like rock or failed. This is where I have about half a square metre of set-like-rock dollops and half a square meter of 'back to the brieze block'.

I'm sorry - I'm not sure if even now I've explained what's there very well.

PS I've just been told by an old boy who used to be a builder that what I've got is the usual bonding & plaster & paint on the upper half of the wall (where I won't be tiling) and on the lower half (where I will be tiling) I've got a mix of sand and cement which they used to apply 1/2" thick direct to the blocks and then set the tiles directly into that. Apparently it sets like rock to the blocks and to the tiles - which would explain why it was so tough to get any tiles off those bathroom walls and I ended up back to the blockwork everywhere!

Eeeeeerm. I think I'd still hack away at as much tile as you can, it doesn't matter too much about the neatness or flatness of the blocks as when you overboard, providing you've got the tile off every 300mm or whatever the distance is between each blob of 'dot and dab' adhesive, you'll be making it plumb and neat again. I'd even consider dot and dabbing the whole lot (right up to the ceiling). With the right plasterboard (the one with the sort of 100mm bevelled edge thing) you can simply skim the joints and decorate the actual palsterboard surface (so paint or wallpaper or whatever). But then you have a solid flat surface to tile on, and you'll have no problem with depth differences between the top and bottom halves. With a nice tile trim it'll finish off well and be easy, and you wont need to wait for anything.

The hardest thing to do will be to chip away at enough of the tile to give you a fixing to the blockwork every 300mm, or whatever the distance is required between each blob for the plasterboard adhesive.

Don't know if that's what the lads would bother doing above?

Although the tiles seem to be really solid, I think the amount of hassle involved in tiling over all the bits that have different depths and whatnot. And the wall you say that's really bad will need quite a bit of attention. It's just not worth not re-boarding. It'll be finished to showroom quality if you do overboard. Though it might not be as pretty and it'll certainly be more time consuming if you don't.

(that is if I've read your explanation correctly and we're on the same wave length here)

Ummm. I'm not too sure if I've explained it okay and we're on the same wavelength yet.... so just to check...

Where they put on this sand and cement mix they didn't just 'dot and dab' it - it's was applied so as to cover all but the odd square inch here and there - it covers 95% of the wall behind the tiles; it's 1/2" thick and in 5 and 1/2 square metres it's still solid as a rock bonded to both blockwork and tile. (That's 3 out of the 4 walls and they're flat and true - just they've got the old tiles on). There's just one wall of half a square meter where something must have gone wrong in the original tiling work and I've a mix of places where the tiles have come off but the sand and cement layer is still sound and places where tiles and this 1/2" thick layer of sand and cement has come off as well.

Now - you tell me! Are we on the same wavelength?

Just a suggestion, but do you have any photographs you can post? I find that easier than describing things.

I had the same problem, tiles were stuck solid, so thought I would tile on tile, however after research on this forum and many hours of searching the net, everyone gave the same advice no matter how much they are stuck, get them off. I was very reluctant to even try as I knew once started had to finish. But after hours and hours of thinking about it, I got the chisel and hammer and had a go. Took me hours and hours to chip away at a square of 300mm. But knowing how much I had paid for the tiles sitting down stairs kept me going. But would you believe it I had a few spots which just fell away, how sad is it when you get excited about tiles falling off a wall.
I went through bags and bags of render as when I was finished the walls were a right mess, but was worth it in the end. Nice flat service for my tiles.
Sorry for the long winded reply. And sorry to my neighbours for the banging day after day, they are diamonds.
Best of luck

This 1950s fixing is sand and cement, the tiles were soaked overnight and then fixed 3:1 sand and cement onto a scratch coat render. When this method was done correctly, it would take world war three to remove them. If you can get back to the original brick, then as above dot and dab plasterboard, all well and good, but be warned. Good sand and cement fixing does not yield easily.