Hi All.

I just wanted to start by saying I have read hundreds of posts and find this forum an amazing source of information. So, thank you all!

I am about to renovate an existing bathroom and put in a wetroom shower area. We are quite nervous about leaking, broken grout etc. I have seen a number of tanking options out there, and I was thinking of incorporating 2 as an extra level of protection. I am crazy? Too much?

The room has chipboard flooring currently. The plan is to replace this with 18mm ply, then lay 10mm Marmox over this (adhesive layer in between, then fixed with screws/washers). The walls are studs and block work. I was thinking 20mm Marmox all round. Plastic dowels for fixing to the block, screws/washers for the studs. I like the sounds of Marmox because it insulates (both sound and heat) and it is waterproof. After floor and walls are fixed, tape over joins/seams etc with waterproof tape.

I am then intending on tanking with Dural Durbase CI+ membrane.

We are thinking of electric underfloor heating and marble tiles.

I haven't chosen a shower tray former yet, but this probably doesn't change anything.

Any opinions on this approach would be greatfully appreciated.

Regards,
Jonathon.

Hi Jonathon..

Marmox boards are great...

I agree on the removal of the chipboard , this will give you chance to add some extra noggings to the joists to receive board edges etc.

Then you can SBR prime the underside and edges of the new ply sub-floor, then as you say overboard with 10mm marmox, now marmox do say you can overlay onto timber with no fixings but i like you prefer to add fixings over timber floors..

What you could do is screw down as you say and then lay your UFH, slc over this to create a nice flat bed and then tank with Dural CI+ to create that tanked floor and help with eliminating stress to the marble... seen as you are using marble then again use the Marmox on the walls and fix as you say, then use the marmox self adhesive tape to cover the joints and fixings and internal joints to corners and floor/wall transitions.

If you click the link in my signature and talk to David at PHG Wetrooms, he can supply all your material needs and chat to y ou about your tray requirements...

Good luck and let us know how you get on.

As above, it's exactly how I would do it......


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Thanks Dave.

Excuse the dumb questions, but what is the purpose of the SBR primer on the underside and edges of the ply? Also, would you tank the shower area walls with membrane too, or is the Marmox sufficient. Do the preformed membrane corners you can buy work any better or can you just make them up from the tape easily enough?

Hi..

The purpose of the sbr to stabilise the ply from any air moisture within the cavity of the joists etc...


Marmox... yes if you tape the fixings and joints properly then you will have no probs but if you really want peace of mind then use the Dural WP as well...

Corners... pre-formed are great and not a bad price either but yes you cam make yo ur own.. i have done may times but peace of mind, then use pre-formed..

Thanks very much! All makes sense.

Do you rate Weber floor flex for slc?

It is a good slc yes... min depth on timber floors is 10mm , so maybe opt for Mapei renovation screed slc.. about the same price..

All great advice above you cant go wrong following that.

20mm for the walls? is that a bit much? I used 12.5 in mine.

Jonathon, check the link to my bathroom build in my sig... I pretty much did as you are planning, ie: 2 methods of tanking / overkill

Agree with advice given. My post on Marmox products may be of some assistance... Marmox ..... a quick guide to their products