Redoing the En Suite

NoNameNoNumber · 11 May 2022 at 14:29

We recently moved house, the en suite was nice stuff, but really badly fitted, around 5 years old.
I've started demo-ing the lot, main goal is to fit a wet room/ walk in shower like we had at the old place and to drop the floor level so it's not a 20mm step up from the bedroom carpet.
I do have a couple of questions for the more experienced among us

1, I've made quite a mess of the plasterboard, so intend to just redo every wall. Green 12mm square edge vapor board the stuff to use? 3 walls are stud, the 4th is dot and dab.
2, The original subfloor (guessing chipboard) has 18mm play laid on top. Can I remove both subfloors, refit with 18mm structural ply, then 6mm hardibacker, flex levelling compound with heating matt in then tile? That would drop my height difference by around 10mm.

Buffman · 11 May 2022 at 16:53

1. I'd go with a waterproof tile backer e.g. Marmox boards or jackoboard in the shower area (best to go with 12.5mm to align with the rest of your walls). I believe if studs are wider than 600m centres you need 20mm marmox boards so worth checking datasheets before you buy.

2. Yes. Or you could buy 18mm chipboard then put hardi backer on top. Overboarding 18mm with 18mm ply seems mad. Are you sure this is what's been done?

NoNameNoNumber · 11 May 2022 at 19:34

OK thank you.

1, I see marmox, hardi backer, jacoboard etc, some cementitious, others polystyrene based. Is one better than the other?

Also, DITRA uncoupling matting, is that a better option on the floor instead of tile backer?

2, I'm not sure if the original subfloor is ply or OSB but it's definitely been doubled up.

JRJ · 12 May 2022 at 10:58

N&C/Nicobond do their own version of tile backer board which I've used and comes in a lot cheaper than the bigger brands, if you've got a store locally its worth popping in and having a friendly chat for a nice discount, specs are identical to Marmox/jackoboard and as quoted by @Buffman above.

I wouldn't worry too much about Ditra on this occasion, 6mm backer on primed OSB with a decent flexy adhesive and then screwed will be rock solid.

b0rn2sk8 · 12 May 2022 at 11:16

Buffman said:
1. I'd go with a waterproof tile backer e.g. Marmox boards or jackoboard in the shower area (best to go with 12.5mm to align with the rest of your walls). I believe if studs are wider than 600m centres you need 20mm marmox boards so worth checking datasheets before you buy.

As above for the shower area, it saves tanking the shower area although it is more expensive.

You should also check the tile load rating if you plan to tile, plasterboard isn’t strong enough for certain tiles and you need to proper tile boards like those mentioned above anyway.

You can always add more studs if you need to rather than going for thicker boards.

The polystyrene based boards have insulating properties if that matters to you.

200sols · 12 May 2022 at 16:45

NoNameNoNumber said:
1, I've made quite a mess of the plasterboard, so intend to just redo every wall. Green 12mm square edge vapor board the stuff to use? 3 walls are stud, the 4th is dot and dab.

Standard plasterboard is fine, in wet areas (shower/around bath) use marmox/jackoboard or similar. Much better.

NoNameNoNumber said:
2, The original subfloor (guessing chipboard) has 18mm play laid on top. Can I remove both subfloors, refit with 18mm structural ply, then 6mm hardibacker, flex levelling compound with heating matt in then tile? That would drop my height difference by around 10mm.

Rip it out and board with 18mm chipboard or ply*, get it level on the joists first using shims etc, screw it down securely. Overboard that with 6mm marmox if using under floor heating, otherwise just use hardi boards. As your floor will be level use a 6mm trowel and a standard flexi adhesive, mechanically fix the boards as well, the role of the adhesive here is just to take up any unevenness in the floor let the mechanical fixings do the work. Use a class S2 adhesive for tiling the floor. If tiling yourself use a slowset adhesive, you have no need to use rapid setting products and put yourself under pressure.

*The quality of many plywoods these days is terrible, it really isnt worth the premium.

Participant · 12 May 2022 at 22:42

200sols said:
Use a class S2 adhesive for tiling the floor. If tiling yourself use a slowset adhesive, you have no need to use rapid setting products and put yourself under pressure.

I couldn't find any standard setting S2 adhesive when I looked. Are there any?

Orifice · 12 May 2022 at 23:01

Mapei Ultralight S2 has an 8hr pot life.

NoNameNoNumber · 14 May 2022 at 12:24

Here's the latest.
Original subfloor is 20mm tongue and groove. The stud wall is sitting on top and nowhere near any joists, what do I do with that? Am I still best replacing this? I'd need to hack some more holes to get the pipework where I need it.

Also, the external wall, would it be sufficient to fill the holes with some browning plaster and tile straight onto that?

Floor joists are 220mm x 45mm on 450mm centres

200sols · 14 May 2022 at 13:11

NoNameNoNumber said:
Original subfloor is 20mm tongue and groove. The stud wall is sitting on top and nowhere near any joists, what do I do with that? Am I still best replacing this? I'd need to hack some more holes to get the pipework where I need it.

That is how they do it. Does this floor have any flex in it or is it solid? Is it level?

NoNameNoNumber said:
lso, the external wall, would it be sufficient to fill the holes with some browning plaster and tile straight onto that?

Fill holes up to a reasonable size with tile adhesive. As long as the wall is pretty level and your tiles arent heavy it will be fine.

ANDARIAL · 14 May 2022 at 13:16

DO NOT choose porcelain tiles if possible (personal opinion) very hard to cut and a pain to fix as the adhesive needs to be mixed not got from a tub

NoNameNoNumber · 14 May 2022 at 14:36

200sols said:
That is how they do it. Does this floor have any flex in it or is it solid? Is it level?

Fill holes up to a reasonable size with tile adhesive. As long as the wall is pretty level and your tiles arent heavy it will be fine.

To be fair it is pretty solid. I'm struggling to see how I could get the wastes down into the floor anyway so perhaps it won't need lifting.

If these boards stay, what's the best to lay on top before UFH and tiling?

Do I need to prep the sections of wall that still have paint on them?

ANDARIAL said:
DO NOT choose porcelain tiles if possible (personal opinion) very hard to cut and a pain to fix as the adhesive needs to be mixed not got from a tub

The Mrs is swaying towards large porcelain... I'm pretty well tooled up for cutting them though so not too worried. Didn't know that about the adhesive though. Guess you have to prime the porcelain too?

ANDARIAL · 14 May 2022 at 15:10

As has been said check the weight/loading of the pb or whatever board you use.porcelain are heavy
Definately check for correct adhesive,fairly sure it has to be mixed and goes off quite quickly so only mix as much as you can useup
Not sure about priming the porcelain tiles ,before i retired i was only helping out tiling occasionally

NoNameNoNumber · 14 May 2022 at 15:31

Yeah I hear you

Well, I've pulled the floorboards up... basically, for us to have a flush floor/walk in shower, the 40mm waste needs to enter the stack about 80mm lower than it currently does.
And to access that, means floor up and probably a hole in the dining room ceiling

Pics incoming.

Participant · 14 May 2022 at 15:32

Large tiles porcelain or not should be back buttered with adhesive trowelled with the correct width notches and never use pre mixed. Mixing the adhesive is the easiest part of the whole thing if you follow the instructions precisely.

They are harder to cut but the looks make it worth it.

Recommend hiring a wet saw. You can use a grinder to good effect but it takes ages, although you'll need a grinder with a diamond blade anyway for awkward cuts and large holes.

Forget the cheaper score and snap cutters as every other cut will not be straight with the very hard porcelain tiles.

katie279 · 14 May 2022 at 16:51

Just did our ensuite with my other half!

Definitely recommend marmox - it has great insulation values, so useful for heat/sound and dead light/easy to cut.

Go with porcelain - agree re the look! Didn't find it too hard - mostly using score cutting and cut very clean. Used wetsaw for some fiddly bits.

Just get plenty of diamond saw bits for any holes you want in it....! Very hard stuff!

NoNameNoNumber · 14 May 2022 at 17:07

Tiling complications can wait... First I need to fix this waste issue.
I need to get that 40mm waste (EDIT and the toilet waste! )below floor level and over to the left hand wall as you look through the door.
Access to that stack is pretty dire though, even if I go up through the dining room.
HELP

b0rn2sk8 · 14 May 2022 at 17:39

You’d need to notch/drill out the joist but I can’t tell if there is enough joist to take through a 40 mm pipe.

How thick is the joist?

The regs are online here https://www.labc.co.uk/news/how-get-it-right-notches-holes-solid-timber-joists

200sols · 14 May 2022 at 18:14

NoNameNoNumber said:
If these boards stay, what's the best to lay on top before UFH and tiling?

Do I need to prep the sections of wall that still have paint on them?

I would use 12mm hardibacker boards.

You shouldnt tile over paint either, if that wall is plaster boarded i'd just rip it out and replace tbh.

200sols · 14 May 2022 at 18:15

ANDARIAL said:
As has been said check the weight/loading of the pb or whatever board you use.porcelain are heavy
Definately check for correct adhesive,fairly sure it has to be mixed and goes off quite quickly so only mix as much as you can useup
Not sure about priming the porcelain tiles ,before i retired i was only helping out tiling occasionally

You can get slowset adhesives with 6-12 hour working times. Tub adhesive is crap, only suitable for small tiles and sometimes mosaics.