Tiling shower, do I need to skim first?

dnme

I'm doing some work on a 70's bungalow. I have demo'd the ensuite shower. It was in a bad state. I intend to install a new tray, new electric shower, new door and re-tile the walls. The original walls are all internal plastered 4" block. The floor is solid concrete. When I removed the old tiles, the attached image is what I was left with. As you can see, the walls are pretty rough. Should I put a coat of bonding on before tiling? (Apologies for image layout, I simply cannot get the site to orientate the image correctly.)

10-10-20

IMHO, the background is sand-plastered solid-block and as long as it's not loose and flaky, it would be considered sound and the best substrate to use. Example of substrate loadings here:

https://www.ardexbuildingproducts.ie/tiling-large-format-heavy-tiles-need-consider-weight-limitation-substrate/

But I do wonder how you're going to complete that transition from the wall to the tray - You'll need to slope it, but also ensure that the water doesn't pool at the door.

Additionally you should probably consider tanking the whole shower and bathroom. Any thoughts on doing that?

standardg60

I'd certainly install concrete board to the walls prior to tiling anyway

dnme

https://www.boards.ie/discussion/comment/119010281#Comment_119010281

Hi,

No I'll keep it simple for now. The actual width I'm dealing with here is 1050mm. I intend to install a 1000mm sq tray so I only need to bring one wall out 50 odd mm. I may bring out the left wall with stud and plasterboard which will allow me to hide existing pipe. The reason I asked if I should skim a coat of bonding was more to do with getting walls flat rather than and loading questions. If these were your walls would you skim them before tiling or would you tile straight onto them as they are ?

10-10-20

https://www.boards.ie/discussion/comment/119012746#Comment_119012746

No, I would not skim them. If I had to patch or repair the block somewhat they I'd use a bonding coat where needed to make the surface more regular. But you're also considering stud and plasterboard?

https://www.boards.ie/discussion/comment/119011548#Comment_119011548

If you need to enclose pipes then I'd stud it out, but then I'd use a tile backer board in place of any plasterboard (do not use standard plasterboard!), and standardg60 has a good point about maybe considering putting the same tile board on all walls. Just don't forget that you'll have moisture issues with that configuration of a stud (colder wall behind stud), so you'd need to protect against moisture buildup - a tile board will help with this.

Some of the tile backer boards are made from expanded PS so it means that you lessen the heat-loss through the walls of the shower. While this may sound pointless, it will improve the heat retention while the shower is running (you'll only have to warm the tiles, grout and adhesive, rather than the block) and should also reduce the condensation on the walls somewhat. It just means that you'll have a more comfortable shower.

dnme

https://www.boards.ie/discussion/comment/119013394#Comment_119013394

Great points.

I was looking into backing board, I think I'll use backing board rather than skim. What you wrote about heat retention and moisture was great food for thought. Also backing board makes the job easier than skimming. If I go for something like Elements Board, it has a great joining / sealing system with tape and adhesive, just belt and braces. Ok decisions made, on with the job.

10-10-20

Post up a photo as you move along with this. Always interested in seeing progress.