New shower

[Tabitha]

We've had a few bathroom installers round to give us quotes for installing a bathroom in a new extension. All walls are concrete block with plaster. We intend to have a flush shower tray and the shower is situated in a recess between these concrete and plaster walls (i.e. up one end of the bathroom taking up the whole width of the room-2m), so there are 3 walls surrounding the shower tray one of which will be plasterboard/batten built out from the concrete/plaster wall to house the shower pipework. All 3 walls inside the shower will be tiled.
Only one of the installers has mentioned tanking/using waterproof tile boards (not sure which method) and we're a bit shocked with this. We currently have trouble with damp travelling through the wall to an adjoining room in our existing bathroom (another future project) because no tanking/waterproofing was carried out, so we're obviously anxious that our new ensuite bathroom doesn't suffer the same problem.
All the installers seem to think that the grout and adhesive will prevent any moisture getting through to the plaster/wall under the tiles (our past experience doesn't confirm this). One installer mentioned using moisture resistant plasterboard and tiling on top of this without any kind of waterproofing.
Are we right? Should waterproofing be done for the shower area (it's not a wet room)? Are we worrying over nothing and is what the installers are planning will be perfectly ok?

Thanks for your help.

 

[Swwils]

Yes waterproofing should be done to a shower area and it is now recommended in the BS to do so in domestic setting I believe.

BS 5385-1:2018 clause 6.1.1.3 significantly beefed up previous standard and now "recommends" to do so in domestic setting aswell as commercial.

Numerous products on the market to achieve this, tanking systems, waterproof backers, wediboard. Etc.

I guess it boils down to how much you want to spend and how long you expect it to last.

 

[Tabitha]

Thank you Swwils, that is what I gathered from reading online.
Can I ask please what you would recommend for waterproofing our shower area?

 

[Swwils]

Use a product your tiler is familiar with.

Personally I always use KERDI or WEDI board, but you need to know what you are doing to get the best results; that being said the instructions and techniques are clear, it's just the materials that have a relative higher cost. But they are backed by significant guarantees.

You may find that installers with this experience are more expensive, so again it's up to you.
Nothing wrong with cheaper alternative materials like cement based backers aslong as they do they job required and also installed correctly.

I always think it's a false economy to not get it done to last. If you have had issues before it might be because you really need waterproofing due to how you use the room compared to others who might have only used a trickle of water or something.

The selection will also depend on your tile choice, the room, layout and other factors which may favour one thing over another!

 

[Tabitha]

Thank you Swwils for that information. Our regular tiler uses a high street tile shop's waterproof tile board. Whether he uses anything in addition I don't know. We were hoping to get a bathroom fitter who would do it all (plumbing and tiling) but I get the impression they don't want to do a job that will last, just a job that looks good for now. When we've asked about waterproofing the shower area it has been met by remarks like "it doesn't need waterproofing, the tile adhesive and grout are waterproof" and "if you really want it waterproofed I'll tank it using a tanking kit, but it's overkill". In fact the question was met with irritation or amazement. The quotations were several £1000's and did not include any kind of waterproofing, so they weren't cheap.

The internal bathroom extension walls were cement skimmed and plastered over, it didn't go right down to the floor to allow for skirting (which obviously we won't be having in the shower area), so the cement skim/plaster overhangs the bare blockwork bit below by about 1cm, would this cause a problem as there would be a void behind the bottom 4 inches of waterproof boarding? I'm assuming that any waterproof tile board would be installed before the shower tray and would be floor to ceiling?