Tanking / Kerdi on Concrete Board

[iwaters]

I'm replacing my enclosed shower cubicle. The old one dones't appear to have been installed very well and there is a bit of mold on the plasterboard.

I am going to take down the plaster board and replace it with Hardiebacker or similar. I had oringinally planned to go over the board with Kerdi but having seen the price I might not.

Can someone recommend an alternative tanking kit or product to the Kerdi which is cheaper?

Also the cubicle has 3 internal stud wall, these are all insulated (losely) with fibreglass insulation. Should there be a vapour barrier between the insulation and cement board?

 

[tpt]

Depending on the level of existing damage, Rather than rip out the existing plasterboard you could tank it. something like the palace shower tight tanking kit would be ideal.. There are loads of these types of kits available.

Alternatively you could use something like no more ply directly over the plasterboard which would mean you'd be ok with 6mm, and then just tape the joints, but the first method would be my choice.

 

[tpt]

Just to qualify while i think about it, you may want to tell us what you intend to tile with too. if its really large format stuff then my previous advice may have been total rubbish!

 

[Richard C]

I'm replacing my enclosed shower cubicle. The old one dones't appear to have been installed very well and there is a bit of mold on the plasterboard.
I am going to take down the plaster board and replace it with Hardiebacker or similar. I had oringinally planned to go over the board with Kerdi but having seen the price I might not. Can someone recommend an alternative tanking kit or product to the Kerdi which is cheaper?

In al honesty, you don’t need a (truly) waterproof backer board (Kerdi, Wedi, Marmox etc.) unless your constructing a wet room. In domestic shower installations, a cement based “water resistant board” (Aquapanel, Hardibacker etc.) is perfectly acceptable without tanking. They will still absorb moisture if it gets thorough but won’t disintegrate like plaster board (even MR) which is why you should rip it down & start again with new bords. On all my wet area installs, I use un-tanked Aquapanel (which is good value if you shop around); correctly installed you will not have any problems. If you know the tiles your laying, make sure board joints won’t coincide with the tile grout lines.

As stated, tile weight is also something to consider if you’re planning large format tiles.

Also the cubicle has 3 internal stud wall, these are all insulated (losely) with fibreglass insulation. Should there be a vapour barrier between the insulation and cement board?

Insulation on an internal stud is only be for sound attenuation to meet BR’s (how old is your property?), a vapour barrier is not necessary on internal walls or most external walls for that matter.

 

[iwaters]

Thanks for the replies. The existing plaster board is quite badly damaged (some I did when I removed the old tray which had cracked). There is a fair amount of mold on the board as well so I want to replace it.

To be honest I haven't got as far as choosing tiles yet but we may choose a larger style tile so I want it to be able to handle that.

The house is about 14 years old. The insulation on the internal walls is pretty pathetic, looks like the builders just tossed in some they had left over from doing the loft. I wont bother putting up a vaopur barrier then.

The main reason I was considering tanking or using Kerdi is because we have very high mains water pressure and a sealed hot water system so the pressure from the shower head is very high and the flow of water is a vast. The existing shower tray had a standard 50mm (?) waste which struggled to cope with the flow it was so high.

I know I could reduce the flow of the water but we both quite like a nice powerfull shower and so I would rather have a cubicle designed to handle it. I was thinking that with the higher flow of water more will be running down the walls and might be more likely to penetrate the tiles/grout, or is this wrong?

 

[tpt]

given your description of the pb damage i'd agree with richard. rip out and use a cement based backerboard.
No more ply state that two coats of sbr primer makes their backer boards completely waterproof. http://www.nomoreply.net/WETROOMS.htm

Richard any experience of doing this?

Waterproof adhesive\grout will let some water through, it just wont disintegrate like non waterproof ones. The amount will be small but this is why its worth having a cement based board not plasterboard. A big fail point is often the joint between the shower tray and backerboard so dont neglect this. in my own shower i siliconed the tray to the wall(backerboard) and then ran a bead around before tiling too.

 

[Richard C]

No more ply state that two coats of sbr primer makes their backer boards completely waterproof. http://www.nomoreply.net/WETROOMS.htm

Richard any experience of doing this?

Personally never used NMP. As I said, I generally use Aquapanel which is also a cement based board but I never seal or tank these wet areas unless it’s a wet room. My only concern about sealing with SBR is that is will significantly affect tile adhesion, drying/curing time; BAL (which I use more or less exclusively) specifically state not to seal/prime tile backer boards so I assume this would invalidate their warranty.

A big fail point is often the joint between the shower tray and backerboard so dont neglect this. in my own shower i siliconed the tray to the wall(backerboard) and then ran a bead around before tiling too.

I apply a double silicone seal at the tray but after I’ve tiled & grouted. First I squeeze a thin bead (uncut nozzle) well into the gap between the tile & top of the tray, clean off the excess, cut the nozzle to the required bead size then immediately apply the second bead over the top between the side of the tile & top of the tray as normal. You need to be careful when using silicone before tiling/grouting, not much will stick to it including addy/grout so if the inexperienced spread it about too much, it could actually provide a less secure seal.

 

[tictic]

The main reason I was considering tanking or using Kerdi is because we have very high mains water pressure and a sealed hot water system so the pressure from the shower head is very high and the flow of water is a vast. The existing shower tray had a standard 50mm (?) waste which struggled to cope with the flow it was so high.



this might be the reason you have had a failure...sounds like the pressure you would get from a "power shower"...

so i would advise you go for a epoxy grout..i.e bal easy epoxy/mapei kerapoxy..etc.

any other cementbased grout will break down in the situation you have...

 

[iwaters]

The main reason I was considering tanking or using Kerdi is because we have very high mains water pressure and a sealed hot water system so the pressure from the shower head is very high and the flow of water is a vast. The existing shower tray had a standard 50mm (?) waste which struggled to cope with the flow it was so high.



this might be the reason you have had a failure...sounds like the pressure you would get from a "power shower"...

so i would advise you go for a epoxy grout..i.e bal easy epoxy/mapei kerapoxy..etc.

any other cementbased grout will break down in the situation you have...

Thanks, I've heard epoxy grouts are quite hard to use. I'm only a DIYer and have tiled a few things but never used epoxy grouts.

 

[bathstyle]

Epoxy grout

A standard grout will be fine, Kerdi is one of the best tanking systems available, Aquapanel is also a good idea especially for heavy tiles but i would still pop a tanking membrane on 1m from tray- belt and braces.

 

[tictic]

Epoxy grout

A standard grout will be fine, Kerdi is one of the best tanking systems available, Aquapanel is also a good idea especially for heavy tiles but i would still pop a tanking membrane on 1m from tray- belt and braces.

alright bud..how are you,long time...

how things over in the other forum....does look rather dead over there,maybe sigma should post over there a bit more...

re:the above, the op is describing "power shower" output..pressure etc!..

anyway you bored...what brings you back...

hope your busy and doing more m2,than you were last time..

 

[bathstyle]

I'm very busy at the moment, no time for these forums, no idea where the other place is? It's been that long.

With regard to Metres squared that I do per month, the less i do, the more money i get, I'm sure you understand if you know the line of work i'm in

 

[tictic]

good to hear your doing ok...

re:m2...you still fixing them fancy italian mosiac...member dont take the pic and have your reflection in the pic...you look as if you need to go on a weight loss program...lol...only kidding...

you still doing the full installs bathstyle.(high end i hope)..

 

[bathstyle]

I seem to get all the jobs that nobody else wants to do.

I just finished a job with 1000mm x 1200mm quartz tiles with broken glass in, so heavy that they need mechanical fixing which required the biscuit to have a small cut done by a tool and discs imported from Hong Kong. I've only just got back into a proper sleeping pattern after that. How's your work?

 

[tictic]

sounds like that was a good easy job...

what cutter were you using for them babies.

how thick were they,did you use the clips also,...with using the biscuit how big was the spacing/grout joint?..

hope you used a good addy..latex/waterbased?

not fixed that size for a good while,and them were quartz,good to work with or a complete nightmare for calibration?..unless from a very good mfr/retailer..

anyway have been a little to busy, has been for a good while thinking off taking a few weeks off,have a little project off my own coming up.

tt..