Shower refit - Is tanking necessary

Hi,

I am replacing bath with a similar sized shower. Plumber is a friend and recommended tanking.

you may find he is using the green PB as an alternative to tanking: the weak point is the tray and crucially the drainage which will be outside the tanking.
If the substructure is correct, and green PB is sued, wall tanking is over kill in my view.

Sometimes tanking is used as a cover up for poor substructure work

Calahonda52 wrote: »

you may find he is using the green PB as an alternative to tanking: the weak point is the tray and crucially the drainage which will be outside the tanking.
If the substructure is correct, and green PB is sued, wall tanking is over kill in my view.

Sometimes tanking is used as a cover up for poor substructure work

Green PB is just a moisture board and not an alternative to tanking. Tanking is always recommended for new shower area.

Builders who do not wanting to be getting phone calls about showers leaking or tiles coming away from walls because the plasterboard behind it has disintegrated due to damp. Its not an expensive thing to do and a handy DIYer could do it after watching a couple of videos so for the sake of an extra €60 an a couple of hours why would you not do it?

For clarity i am in the building trade and have had to deal with retrofitting showers that were done by others and not tanked at the time and its a huge expense and inconvenience for the client to do this after the fact.

Shower areas shouldn't leak but they can, I can show you €1m houses that have.

Its a simple extra precaution that's all.

I'm currently building an estate where houses aren't far off €1m each to buy that have no tanking. I'm also doing an en-suite at home and do you think it will be tanked? Bet your ass it will.

mickdw wrote: »

I specify tanking for any works im involved with. Too much messing when problems occur after without it.

That is a very sensible approach: its a professional's call rather than some "recommended practice"

Hi, plasterer in today as not tiling whole bathroom. First question he asked was shower area tanked. He has just replastered a kitchen ceiling where shower above not tanked. Massive discussion between him, plumber friend and hubby about the perils of not tanking.

leinster93 wrote: »

As it turns out, following agreeing on me to tank the shower he detailed that he needs to change the board around the shower to concrete plasterboard and referred the original board as standard; not even the moisture resistant board I assumed would have been used. I proposed I'd take the hit on the tanking kit and tank it myself in the evening.
With the addition of tanking it he increased the cost referring to the difference in changing the board around the shower. Likely he'll see this thread but will know why I decided not to proceed with him...

I thought this guy was a professional, he should be telling you what’s required rather than you having to research the matter and advising him what you want. Granted different trades will do things differently but just because he’s applied one method for 20 years doesn’t mean practices and products don’t evolve. There are so many different methods and products available such as Schluter Kerdi board and equivalent waterproof substrates for tiling now.

Plasterboard of any description, greenboard or moisture resistant board, ideally shouldn’t be used in a shower or anywhere that has high concentrations of water. Cement board (doesn’t degrade when wet) is good and it’s what I’ve personally used on an ensuite remodel after I had to take everything back to the joists/studs due to terrible workmanship on prior install where big expensive 800x450 porcelain tiles were dot dabbed to plasterboard walls with leaking grout. If using cement board as your substrate make sure he doesn’t use pasterboard screws to fix them to your studs as the cement will eventually erode them. You can get specific cement board screws that have increased corrosive coatings such as ruspert that will be tested to a minimum of 500hrs of salt spray. Also if using jointing tape to join boards you can get alkali resistant tape instead of that generally available for plastering.
Is he charging you much more for the use of cement board around the shower area? For comparison standard 8’x4’ 12.5mm plasterboard is about €10 a sheet while greenboard is approximately €16 but cement board is around €50. It also a lot heavier and a bit of a pig to lift on your own plus it’s more difficult to cut. Depending on the size of your shower area you’ll need at least 2 but likely a third, I used 3 ½ sheets in mine.

In terms of your initial question as to whether a shower area should be tanked, why would you not. Tiles and showers are expensive and water damage exponentially more so therefore the more preventative measures you can apply the better. Belt and braces all the way where showers/water is involved especially on a 1st floor or higher. You’ll get a large tanking kit for about €75 and even less for a standard kit or if you shop around so in the grand scheme of things it’s not a significant extra. Cement board, like plasterboard is not waterproof so should be tanked in my opinion. Ideally once a shower area is tanked it should be waterproof and fit for use without any tiles being laid. Tanking kits consist of a primer, jointing tape, drain matt (if going for a wet room rather than shower tray) and a rubber like paint that’s applied over at least two coats. For a real waterproof tanking system you could have the whole area done in fiberglass but that’s into another realm of cost and preventative measures.

leinster93 wrote: »

. As posted in another post, it's a second line of defence if the grout fails.

Toby22 wrote: »

Friend is a plumber by trade from years ago but got into family asphalt business and tanking is his motto. Obviously not tanking shower in asphalt but he said grout will eventually breakdown

Common areas of failure in showers are the drain connection and the seal between shower trays and walls but all too often grout fails especially in corners which should use silicone rather than grout due to movement between the planes. Grout in itself is not waterproof and will degrade/stain over time but another preventative measure on that front is the use of epoxy grout but it’s near impossible to source in Ireland at any reasonable levels. I’ve spoken to a number of tilers and tile suppliers and there is zero appetite for it here as it’s a lot more difficult to work with and cost/wastage is a big concern. I’ve been quoted prices as high as €189 for a 4kg tub when the same product retails for around £35 in the UK. Would be interested to hear if your professional has ever used epoxy grout in his 20 years. If using standard grout you can seal it afterwards as an extra preventative measure and re-apply the sealer about every 12 months.

Good luck with the project and enjoy the new facilities.

Hi,

I had tiler in today to price tiling bathroom. It hasn’t been tanked yet as we took a few days holidays. However all tanking stuff is in bathroom.

Tiler said shower not tanked , call me when it is.