bathroom preparation help / advice please

[ninjanik]

Hi all,

Please excuse me if this is not the correct section to post this in...

I'm currently renovating my bathroom in a small back to back terrace 1915 circ. I've already made a few mistakes which thankfully reading this forum I've been able to catch in time (tile weights on plasterboard). Tiles will be 600x300 porcelean and cover the floor, back wall and shower end of the bath, and the sink / counter top area.

I've included some photos to hopefully make more sense of my questions


Questions

1) The framework which will carry a semi recessed sink is to be tiled. Whats the best substrate for this?
(ply and tank, ply and mrpb and tank, ply and cement backer or ply and marmox)
This also applies to the bath which will have a 100mm ledge which the bath will sit on on one side before the bath panel (which will also be tiled)


2) The back wall and shower end of the bath have been / will be batoned to hide a concealed shower / bath filler etc. The false walls will also be insulated to try and reduce sound from next door. One problem is in order to get the bath to fit, and hide the shower pipes I'm having to build stud work which will 'lap' over the shower end of the bath i.e. the board will sit on top of the bath lip.

What should I be using for these walls? (mrpb + paint tanking kit, hardi backer + paint tanking kit, marmox + tanking tape)

3) The floor!!!

Its a 22mm wood floor board (original) on joists. the joists span the entire of upstairs and the bathroom is located at the back of the house, so the floor is basically the first 1.7 metres of the joists. The joists dip in the middle of the house quite badly which means in the bathroom the floor slopes by 15-20mm from the wall to the sink.
The floor stable with minimal deflection, although I would feel happier if I could strengthen it.
Whats the best way to achieve this? Im not too fussed about a step into the bathroom as the landing already has 12mm ply on top before carpet.

Really sorry for the long first post... and really appreciate any advice / guidance

cheers
Nick

 

[swanman]

Good luck with your project

 

[ninjanik]

Good luck with your project

Cheers mate... any advice or answers to my questions?

 

[Olz]

Personally I would just use Wedi / Marmox or hardibacker cement board for the lot.

In relation to the lip over the bath made to hide the pipework for the shower, whilst your at it you might as wel change that plasterboard for a wedi / marmox / cement board as well so your not increasing the thickness.

If you can live with the slope in the floor you can screw the existing floorboards down and then overboard them with hardibacker cement boards as long as the floor, once screwed down is deflection free. If its not you will need to take the floorboards up and add extra noggings between the joints to strenghten it.

 

[ninjanik]

Thanks Oli,

I've been down to my local CTD today, and they have the hardi backer boards on offer at the moment - 1200X800 7.99 + vat and they recommended a Ardex tanking kit. I also enquired about wedi boards... and nearly fell over when they gave me the price.
I need to do the sums, ply(for the counter top etc)+hardi+tanking kit vs wedi + waterproofing tape.
Wedi / marmox type boards won't need ply under them... but they will still need sealing and from what i understand, the tap is a fortune?

I'm definately not comfortable using mrpb where it will be lipped on top of the bath shower area... just incase the bottom seal leaks.

The floor is a real concern though. I could lift all the boards and have replaced some already... but I've already started building the frame for the bath ledge etc onto the current boards. Also the soil pipe runs between 2 of the joists right in the middle of the bathroom from the back of the terrace to the front - so cant put noggings in there.

If I was to overboard with 18mm ply - would you try shimming the ply level or use a slc on top?
CTD also showed me durabase matting - laid on top of the overboard to waterproof and decouple the floor?

I'm also gonna research rubber type flooring - as this may work out similar costs for such a small area and then deflection shouldn't be an issue.

further advice really welcome

cheers nick