Some bathroom refurb questions ...

[RogerS]

We're undergoing a major refurbishment.

SWMBO would like to have some gentle background underfloor heating in the bathroom. Current flooring is chipboard. I see some people recommend something like this Budget Backer Board

http://www.theunderfloorheatingstore.co ... ker-boards

to improve warm-up times and reduce heat loss through the floor.

What do you guys think?

Also what thickness tile-backer boards for the shower walls would you recommend? I've seen thicknesses ranging from 6mm (way too thin IMO) to 20mm..which is overkill surely ?

Researching bathroom floor tiling, suggests that I should rip-up the chipboard and replace with plywood ?? Overkill ?

And lastly, if I'm going for one of those overhead drenching type shower heads, is 15mm pipe OK or should I go up to 22mm? The manufacturers website is a bit sparse in detail.

Head spinning.

TIA

 

[Setch]

If you're redoing the subfloor I'd fit plenty of noggins to driven everything up, then fit thick insulation between the joists. The 6mm insulation board will give you extremely little help, but fitting insulation below the floor will allow you to have thick, effective insulation without raising the floor height.

 

[MrDavidRoberts]

btw those backer boards are NOT water resistant, they just don't come apart if water gets on them but still soaks up water and lets it through..
For walls there is no point swapping plasterboard (if thats what you currently got) for cement boards, unless you plan to hang some seriously heavy tiles or need it for structural strength.
the liquid waterproof membranes will do a much much better job, Ripping out chipboard and replacing with plywood is overkill and not needed for sure..
this is your friend:

as for 15mm pipe, it's more than fine... I bet the rest of your pipes are 15mm as well? So you have to change all the rest of the pipes to larger 22mm as well to actually gain anything.

 

[RogerS]

Thanks, chaps. No danger of the joists moving..there is enough steel in the property to influence the earths' magnetic field!

Baths use 22mm pipe, I think.

 

[jimmy_s]

I would lay insulation under the floor to give a reasonable U value. You can loose a fair bit of heat from UFH due to back losses so its worth laying decent insulation. I wouldn't lay floor tiles directly to chipboard and would use WBP ply.

Shower piped with 15mm should be ok if your pressure is ok. Bath taps are normally 22mm (3/4" bsp)

 

[RogerS]

Doing a bit more Googling, there seems to be several opinions regarding the width between the studding (assume a recessed shower). Do you make the width exactly the outside dimension of the tray, slide the tray in and then apply your substrate (backer board etc) onto the studs and down onto the top of the tray, silicone seal the join then tile.

Or make the width wide enough to allow the substrate to be fitted to the studs all the way down to the floor so that the finished width is that of the shower tray which is then slid in etc.

Further complicated, I think, if the tray has an upstand ...

 

[gregmcateer]

Doing a bit more Googling, there seems to be several opinions regarding the width between the studding (assume a recessed shower). Do you make the width exactly the outside dimension of the tray, slide the tray in and then apply your substrate (backer board etc) onto the studs and down onto the top of the tray, silicone seal the join then tile

Or make the width wide enough to allow the substrate to be fitted to the studs all the way down to the floor so that the finished width is that of the shower tray which is then slid in etc.

Further complicated, I think, if the tray has an upstand ...

Depends how wide the edge of the shower tray is - i.e. the 'flat' rim around the main tray that slopes towards the drain. You'll want some rim, so need to allow for the tiles and adhesive. I've done it both ways and as long as you are careful and methodical with your sealing. Either way, I have found sealing the internal join between wall and tray BEFORE tiling (and after as well, of course), does give a better seal.

The real secret is ensuring you have everything supported well - if you can prevent (or minimise) the flex caused by the weight of the occupant - the silicon is far less likely to be stretched and therefore maintain a good seal.

HTH

 

[AndyT]

On tile backing board... When I redid our bathroom, I nearly bought some cement based board, probably Aquapanel, IIRC.
But fortunately I found Marmox board in stock in the tile shop. It's much better - closed cell foam with a glassfibre reinforced cement coating. It's strong, doesn't soak up water, and most importantly it's really light weight and easy to handle.

http://marmoxboard.com/en/marmox_board_ ... ction.html

 

[RogerS]

Thanks, Andy...I'd not come across that one before. The last ensuite I did I used Hardibacker IIRC ...'sold' on their 'score and snap'. Turned out to be more 'score and not snap....rescore and still not snap...out with the angle grinder'!