Bathroom floor

[JCH]

Hi all

I need some advice please. We're redoing our bathroom, we had a seperate toilet to the bathroom but now we've made it one big room, so now we can fit a shower in, I've bought a 1200 x 800 preformed wetroom tray for the shower. The shower will be in a corner of the bathroom and will have a glass screen along the longest side with a small (smaller than the width of the shower) swivel panel on the end. Our floorboards are 20mm thick and in good condition, joists are about 400mm centres. We've chosen some porcelain floor tiles that are 500x300 and am trying to find a matching mosaic tiles for the shower tray. I'd aslo like to put a underfloor heating mat in and already have a tanking kit.

Could you tell me what I need to do to the floor. I was thinking of 12mm overboarding the floor, priming and applying the tanking, laying the underdfloor heating and then tiling.

I've read lots about the use of SLC and plastic matting that detaches the tiles from the substrate but am not sure about the SLC and the shower tray and I'd like not to bring the floor level up too much. I've also seen that people remove the floorboards and replace with 18mm ply.

Any advice would be great!

Thanks
james

 

[tilerbarry]

Make sure you screw all your boards down and then stick hardiebacker 6mm boards to floor with keraquick adhesive and also screws.

 

[JCH]

Hi Barry

Thanks for your advice! So would that be:

- make sure all floorboards are secure
- fit hardibaker (as you suggest)
- prime & paint on the tanking solution (taping the joints)
- lay the underdloor heating

And what would you advise next? Tile straight over the UFH or lay some SLC?

Thanks!!

 

[J Sid]

Before you screw the floor boards down you must check for pipes and mark there position. Would be a shame to tile floor and then to find a damp patch on the ceiling down stairs because you screwed into a water pipe.

 

[AliGage]

What tray are you fitting?

 

[JCH]

I think it's a Weidi, I bought it some time ago. It's a type of foam covered with a cement type coating.

Thanks

 

[AliGage]

Ok what thickness is it? 20mm?

 

[JCH]

Yes it's 20mm thick.

I forgot to mention the size of the bathroom previously. Not including the shower tray and once the bath is in there will be about 2.5sqm to tile.

Thank

 

[jollyroger]

Why are you changing to mosaics in shower area, would look much nicer with an envelope cut sloping to the drain ?

 

[AliGage]

Yes it's 20mm thick.

I forgot to mention the size of the bathroom previously. Not including the shower tray and once the bath is in there will be about 2.5sqm to tile.

Thank

Without seeing what you're up against its always difficult to advise when it comes to "structural" prep.

What I would be leaning toward doing is removing all the current floor boards. Set your tray onto the joists. Fill in between the joists under the tray buy adding supports to the current joists and boarding to bring that area flush. It is imperative that you fully support the tray.

Add plenty of extra noggins and support between the joists for the remaining floor area. Then board over with 15mm WBP ply. Most would suggest 18, but by using 15 you can then glue and screw 6mm hardiebacker over the ply and this will only hring you marginally above the tray height. However, if you use a thicker bed for the tray than the hbb you can get this almost spot on.

Then with a two part waterproof coat such as Ardex WPC I would do the whole floor area and within the wetarea.

 

[JCH]

Great, that sounds good. How is it best to tie in the underfloor heating mat? Lay that over the WPC and then float some SLC or tile straight onto the mat?? If using SLC is it best to bring the shower tray up so that the SLC finishes at the same height?

Thanks for the advice

 

[JCH]

I thought the mosaics would follow the falls of the tray better and was told the envelope cuts can leave sharp edges?

Thanks

 

[AliGage]

I'll be honest, I've never run UFH into a wetarea. I have an idea of how I would do it but ill wait and see if someone else pipes up for you. But FYI I would probably use a fibre based SLC and let it stand in the bucket for a bit to naturally start to stiffen, then trowel it over to try and keep the form of the tray.

 

[JCH]

Ok thanks. I don't think I'll take the UFH onto the shower tray, I'll just keep it to the rest of the room.

Thanks

 

[JCH]

So that I can avoid SLC on the tray I'll set the tray up high but how much thickness should I allow for the UFH mat and SLC? I'd like to set the tray so that the SLC ends up level with the tray.

Thanks

 

[AliGage]

You only need to just cover the mat. Especially if your replacing the floor boards. There shouldn't be a need to "level" so in which case allow about 5mm.