Wetroom Tiled areas - plasterboard or backerboard?

[Conor]

Our stud wall company is supplying moisture resistant plasterboard for our bathrooms and wetrooms. 

 

We have a large walk in shower in our ES wetroom - is plasterboard OK to tank and tile or would we be better off using backer board for the parts we're tiling?

[Temp]

We went for 12mm Hardi backer board and would do so again in shower areas. Its hard work to install as its so hard and heavy but our builder recommended it and its bomb proof. I've fixed things like soap dishes and into it and they have remained solid for >10 years.

[Faz]

Can't go wrong with hardi backer.  However, no-one on mine wanted to use it so up went green board. I used 3 coats of the Everbuild wet room tanking system on all wet areas - simple paint on application.

[Gone West]

I also used 12mm Hardie Backer board for our wetroom. It's heavy and a bugger to cut but I think it'll still be there for many years.

[Pocster]

Backer board of some type NOT plasterboard . Slightest leak and you are (expletive deleted)ed 

[Pocster]

Ditra backer board . Light weight and easy to cut 

[Onoff]

12.5mm Knauf Aquapanel here then Aquaseal tanking membrane over that in the wet room corner. 

 

[Pocster]

  On 21/09/2021 at 19:48, Onoff said:

12.5mm Knauf Aquapanel here then Aquaseal tanking membrane over that in the wet room corner. 

 

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Rubbish 

[Onoff]

  On 21/09/2021 at 20:35, pocster said:

Rubbish 

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All true. 

[markharro]

I have installed Hardie backer for our shower enclosure but for the rest of the room I won't need to use this but the question is what is normally used? Moisture resistant plasterboard? We indeed to lime plaster whatever we use if that is relevant and the board will extend to within about 3mm of the (concrete) floor as a shadow gap.

 

Also do you need to use moisture resistant PB for the ceiling in a shower room? thanks.

[Pocster]

  On 23/02/2025 at 12:47, markharro said:

Also do you need to use moisture resistant PB for the ceiling in a shower room? thanks.

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I did because of ‘fear’ if I didn’t 

I then once skimmed used a bathroom paint I.e forms a ‘skin’ that’s moisture resistant.

[markharro]

And suggestions for wall board in shower-rooms?

[Nickfromwales]

  On 23/02/2025 at 12:47, markharro said:

I have installed Hardie backer for our shower enclosure but for the rest of the room I won't need to use this but the question is what is normally used? Moisture resistant plasterboard? We indeed to lime plaster whatever we use if that is relevant and the board will extend to within about 3mm of the (concrete) floor as a shadow gap.

 

Also do you need to use moisture resistant PB for the ceiling in a shower room? thanks.

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I have been fitting high-end bathrooms and wet-rooms for most of my life, and I personally dislike backerboards. 

 

I always used MR plasterboard and tank the living daylights out of it, with strips to internal and external corners / junctions etc, and I have never had a room leak; that includes wet-rooms on the 1st floor over timber floors and posi-joists etc etc. The only time I selected backer board (15mm thick) was to create a bespoke double-ended walk in (his&hers) shower area from scratch (2700mm x 900mm) as nobody on the face of the earth made one.

 

Belt and braces with timber and gaps, plenty of screws and adhesive, tanked until my arms fell off, still good to this day.

 

You may as well use the MR on the ceiling, cost difference is a couple of pints.

[jayc89]

  On 25/02/2025 at 23:20, Nickfromwales said:

I have been fitting high-end bathrooms and wet-rooms for most of my life, and I personally dislike backerboards. 

 

I always used MR plasterboard and tank the living daylights out of it, with strips to internal and external corners / junctions etc, and I have never had a room leak; that includes wet-rooms on the 1st floor over timber floors and posi-joists etc etc. The only time I selected backer board (15mm thick) was to create a bespoke double-ended walk in (his&hers) shower area from scratch (2700mm x 900mm) as nobody on the face of the earth made one.

 

Belt and braces with timber and gaps, plenty of screws and adhesive, tanked until my arms fell off, still good to this day.

 

You may as well use the MR on the ceiling, cost difference is a couple of pints.

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That's a relief 'cos it's exactly what I've just done in our ensuite after reading all the tiler forums saying the exact opposite 😆

[Nickfromwales]

  On 26/02/2025 at 09:28, jayc89 said:

 

That's a relief 'cos it's exactly what I've just done in our ensuite after reading all the tiler forums saying the exact opposite 😆

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Yup lol. I just think it’s too brittle and a pig to fix, and I’ve seen loads of the backer board installs where the tiler still tanks everything anyways, so why beat yourself up cutting that PITA stuff up. Also seen the screws and washers rusted out so no confidence of the longevity of the fixings that these are so heavily reliant on.

 

Last en-suite I did, 1st floor in a 16th century cottage, I had reinforced the floor heavily, and tanked everywhere. I then made up the 1200x1000mm wet area and fitted the drain. No tiles at this point. Wetroom former tanked too, even though technically the Wedi type stuff doesn’t need it.
 

I set my Rubi 1200mm wet tile saw up in the corner of the room closest to the drain, and then tiled the whole room with travertine. Had the hosepipe in the room with me throughout and literally rinsed the machine bed off after every cut, all going on to cardboard and the waste water going onto the tanking, and then into the drain. Coupe of weeks of that before the room was all tiled, walls and floors, plus I made the sills out of mitred trav too, and not a drip anywhere (clients office was directly underneath). Cleaned the cutter up and evacuated the room, then took my baby cutter back up and mosaic tiled the wet area and then grouted and sealed.

 

Bombproof.

 

Tanking is cheap enough to go mad with it, so no excuses, and best advice is don’t be a tight arse there!   

 

*Drain was a straight run of 50mm pipe, which, yes, I did clean out afterwards. 👍 

[Nickfromwales]

 

 

 

 

 

I thought the mitred shelves / sills looked a bit beefier, but were a time consuming pita to get all the bits matched so it looked like a thick bit of the same material. Worth the effort methinks. 

[Pocster]

Still prefer ditra backing board . Lightweight , very strong , keys easily to tile adhesive .

In a shower still tank it though of course .

I use this board for lots of others things like inside of Lightwells / ceiling backer . It’s just so good as a lightweight bonding agent .