Hello,im about to tile my bathroom and i have some issues with the soundness of my walls! one of these walls will have to come down as the mortar and skim has completely failed to adhere to the thermablock and as a result the wall souds hollow and crunches when you press it,if you find the edge of the mortar and apply finger pressure under it the whole lot lifts from the wall,there is hairline cracks everywhere in the skim coat (at this point i would just like to say i did not build this wall ) the thermablock mortar bed also does not seem to have Adhered either..you can wiggle the blocks.I want to remove this wall which separates bathroom and kitchen(non load bearing) and put up a stud wall and may consider hiding the radiator plumbing in it.The wall will obviously need to hold my tile plus grout,the tile size is 400mm long and 300mm high and approx 6mm thick,my questions are what board should i use? i was thinking on bathroom side aquapanel as this wall will have the non tap end of the bath butted up onto it,and on the ktchen side of the wall use moisture resistant plasterboard? could i use moisture resistant plasterboard on both sides? bearing in mind i may/or maynot hide the plumbing inside the wall.To satisfy building regs i understand i also have to soundproof this wall with 25mm rockwool roll,do i also have to lag the pipes? The other 3 walls are also a problem as they are a horsehair plaster! covered with a slightly flaky (prior to sanding) enamel like paint and in areas this has come off to reveal the substrate.piccys to follow!

bath 011.jpgbath 023.jpgbath 015.jpgbath 016.jpgbath 004.jpg

The first two pics are of the thermabloc wall and the other 3 are a good example of the other walls general condition,the large area to the right of the window frame in the fourth pic has been cut out to get rid of a 2cm render height difference where an original was removed,the thermabloc wall was put in its place to extend the bathroom.My main worry is that the walls have a slightly flaky enamel like paint over the horsehair plaster and it would be this coat the tiles have to stick to! i was going to just render up the cut out sections of wall (not yet done) sand the flaky paint to give key (done) and the little holes i made with a sharp point of a brickys hammer(to give grip for the adhesive) im not 100% that this would be good enough to hold the tiles,i thought of stripping right back to brick screwing thin batons to the brick say 600mm apart then working off the batons to render level,then remove batons render the holes left by the batons(no wood left to pop tiles) and tile directly onto mortar bed using cement based adhesive! would this be the right thing to do? is there a better way? is it overkill ie do you think if the wall cutouts were patched with render the wall may be sound enough,many thanks for taking the time to read my post and for any advice given.

More piccys here...bath 002.jpgbath 003.jpgbath 013.jpgbath 014.jpgbath 012.jpg

I would lower the ceiling mate, to the extent that it comes below the pipes.

I would also consider dot and dabbing the wall with plaster board if you feel they are up to it.

Plasterboard would be enough on both side of the new stud wall but I would tank the shower wall if the shower is fitted to that wall.

I there will be an internal corner where the shower is tank internal area

failing that you can fix board to the wall via framing or furring

The render on the thermolite blocks looks to strong for the block, normally they would have a lightweight gypsum plaster...which dos'nt stop cracking though..

The best thing is dry line the thermolites.

The ceiling need dropping as already said, could get someone to do a gypliner light weight metal system which would allow you to have down lighters if required..

Thanks for the replys ,some very good ideas i never thought of dry linining the thermabloc wall! forgot to mention that the nasty looking plumbing in question will be re routed into the floor space above (doh! sorry my fault) this plumbing was hidden by coving with a fillet piece underneath to extend the cove from the wall,if i lowered the ceiling i would still have the pipes running down the wall,in the 4th photo of the second lot of pics is where the pipes will run and will be the shower wall,the cold water feed comes first to the kitchen sink then runs behind cupboards up the wall and straight into coving in the kitchen then straight into the porch coving then bathroom coving (now took down) then the feed goes down to the bog along the bottom of the wall to sink...bath then combi boiler and the hot does exactly the same in the opposite direction from top to bottom..although not feeding the bog of course be funny if if did mind because id have a steaming hot toilet come bidet/ass cleaning receptacle .Whatever i do to the walls i reckon i will have to go back to the bare brick because the bathroom is only as wide as the bath!(another forgot to mention) and im really gonna struggle with the gap between the taps and the wall which at present with render is only 4.5cm from tap to wall! and thats with a 685mm bath...hardly room to swing a cat...the cat says thank for that.Can i screw/rawlplug plastboard onto the block will only using thin spacers to level the board? what tanking product would you advise? and would normal sand/cement render be ok to tile on? if i chose that route (because of the minimal width) thanks again to all,much appreciated! got the grey stuff going now

You could tile onto sand and cement but I think BAL have a fast setting render product that you can tile onto also (never used it but have spoke to a few peeps that love the stuff)

Thanks again for the reply I liked the links to your webpages TFS some top work on there! espescially the floor tiling on exterior grade ply as i may have to do the same with my floor as its got the good old council issue vinyl/asbestos tile(laminate floor over) but thats yet another story...found some interesting posts on the use of BAL quickset render here Rendering a wall
I then got onto thinking about using quickset cement in the render mix...i guess i would be using a render coat of a minimum thickness of 1 inch? not sure if this could be done in one coat? due to shrinkage...has anybody got any tips on applying render to bare brickwork? such as if 2 coats are a must for a 1 inch bed using quickset cement? how the render should be finished (im guessing just plasic trowel?) and what primer would be good to use on the bare brick and render surface,im also still a little unsure wether i need to go back to bare brick at all or wether just too patch my cutouts with BAL quickset or similar product...sorry for all the questions and a huge thanks for all advice so far espescially as your on here when you could be down the pub!! heres one on me

sorry re_edit on duplicate post