Alternatives to 22mm NMP TG4 on wetroom floor?

[SJRSJR]

So I previously did a lot of research into wetrooms and thought I had it all decided. I was going to use NoMorePly 22mm TG4 screwed and glued to the joists with an Impey Aquadec 22mm former, all tanked with Impey Waterguard membrane which acts as a decoupler for the tiles. What I liked is that it's just the one layer and keeps it to 22mm.

I've already bought the Aquadec former and membrane and just as I'm about to place the order for the rest, I'm getting nervous! The TG4 boards are getting on for 50 quid a square metre so it's going to cost over £1000 over a couple of rooms.

Given that I'm tanking the floor, is there a cheaper way of doing it that doesn't cut corners but works with a 22mm wetroom former?

Thanks

 

[SJRSJR]

I can see it’s quiet at the moment but just giving this a bump.

 

[mrrusty]

Possibly https://www.cwberry.com/kronobuild-p5-fast-shield-tg-chipboard-flooring-2400-x-600-x-22mm

I had an offcut piece left outside in the rain for 6 months, and then found a use for it. It hadn't delaminated, warped or twisted and the core was bone dry after I cut the T&G off. Designed to be left out in the weather for a couple of months during a build until the building gets watertight. I'm fairly sure with a tanking over it would be fine, but I don't think its a designated use

 

[StephenStephen]

Hardiebacker?

 

[SJRSJR]

Thanks - I don't think Hardiebacker is structural so it would have to go over something else. What do people use these days? Previously I used marine ply but that seems to have its critics. I pulled out chipboard and don't think I'll be putting similar back in unless the moisture resistant stuff is much better.

 

[mrrusty]

The stuff I linked to isn't just moisture resistant - it has something like a laminate surface which makes it very water resistant. When I last used it for a floor, it was exposed for a couple of weeks during which we had torrential rain and water pooling on the surface. No issue whatsoever.

 

[yorksbuilder]

The TG4 is your best bet in my experience, very solid, won't have issues with it later


An alternative may be https://relentlessmicrocement.com/product/kudos-aqua4ma-wall-and-floor-panels/

But this may cost even more and I don't think it's tongue and groove

 

[sophiembc]

If you're looking to reduce the cost without compromising quality, it might be worth considering MgO boards like AquaBoard Eco, or the cement-faced tile backer boards like Baseboard. Both are moisture-resistant and suitable for wet areas — especially when combined with a tanking system.


Baseboard starts at 4mm thickness, so it gives you more flexibility around height build-up while still offering compressive strength and insulation.
AquaBoard Eco is a great value option if you’re already using a full membrane over the top (like your Impey setup). Alternatively, the aquatank tanking system gives full waterproofing, comes as a complete kit and is ready to tile in 2 hours.

Might be worth checking with your supplier on pricing for these as they are available across the UK.

 

[yorksbuilder]

Are you a bot Sophie or just joined for this and posted using chat gpt?

The OP wants a single layer structural board that matches height of shower tray, without using a wood substrate. If he wanted to he probably would have already bought 6mm NMP and overlaid the floor

 

[SJRSJR]

Thanks for the helpful replies.

it has something like a laminate surface which makes it very water resistant

Thanks mrrusty. FWIW AI tells me that it’s not suitable for wet rooms but I guess it’d okay if I put tile backerboard over the top. But if I’m going to do 2 layers I wonder how P5 board (which is the Kronobuild), compares to WBP ply?

An alternative may be https://relentlessmicrocement.com/product/kudos-aqua4ma-wall-and-floor-panels/

Thanks yorksbuilder. They are more expensive per sq m but at first glance I’m a bit confused by them. They seem to be sold as a final finish but it also says they’re suitable for taking microcement products (nothing I’m familiar with).

So I could look at 18mm sub floor (P5 or other) with 4mm backerboard on top but I think the minimum backerboard thickness for floor tiles is 6mm so that makes 24mm instead of 22mm. Maybe 2mm is neither here nor there, so I’ll weight it all up. Materials wise it’d be cheaper but then there’s the time spent doing it twice.

 

[mrrusty]

Unless you are intending your flooring to be part of your waterproof barrier, the product I linked IMHO will be fine. I'd certainly use it in a wetroom. Last time I used it for a floor on a build it was exposed to the weather for 2 weeks before the roof went on with water pooling on it. No problem whatsoever. It has a sort of laminate surface - not just a moisture resistant chip

 

[SJRSJR]

Thanks, I’ll look into it. So how did the laminate surface interact with tiles and/or a decoupling/tanking membrane?

 

[mrrusty]

I didn't tile over it, so can't say, all I can say is that I would use it for any flooring application where there is a possibility of damp and/or you are building exposed to weather. Having used it, I'm very impressed.

 

[yorksbuilder]

It looks good stuff, I have used it before construction decks but it's not meant to be tiled over, USB better to getting a moisture resistant chipboard floorboard type products and then overlaying with cement board. Done this many times and had no issue, just pack up your shower tray slightly to match the level. Or go ahead with the tg4