Hi,

So Im laying UFH (warm-up) in my bathnroom.

Ive covered joists with 18mm wbp ply which will be primed, then 2mm flexi adhesive,then 6mm insulation boards, then 2mm UFH, I am then going to self level over top - how much I'm not sure but would say 3mm.

Ill then tank then adhesive and then tile.

My problem is, that if I do all this my floor will be raising up about 20mm! Do you guys think thats acceptable?

Could I lose the insulation boards?

Is UFH really worth it? - any opinions?

Is there anything that ive listed that you guys thinbk I could get rid of to bring the floor level down.

Thanks
Mark
Plumber

Is the 20mm increase only a problem at the door threshold or is it causing problems elsewhere in the room?

Originally Posted by Bri

Is the 20mm increase only a problem at the door threshold or is it causing problems elsewhere in the room?

Hi, thanks for reply

I assume the only problem will be at the door threshold - think this will be ok?. I am only laying 4sq m of UFH on a 9sqm floor and assume I will just use SLC to level the rest of floor.

I'm just wondering if i insulate between joistswill the insulation board for the UFH really make that much of a difference?

If you can insulate between the joists I can't see why that wouldn't work, I assume you'd be using thicker insulation say, 50mm? What floor covering is the tiled floor meeting up to? If its carpet and underlay the total thickness will be about 15mm so it's only a 5mm height increase which can easily be hidden with a threshold strip.

your floor will end up more than 20mm imo but you can make or buy threshold bars to deal with this

if you don't use insulation boards you will lose heat by heating the ply up. not only a waste of heat but it will take longer to heat the tiles up. you can sometimes get away with running the boards along the landing to prevent the step (only if you haven't got bedrooms coming off it)

Originally Posted by kilty55

your floor will end up more than 20mm imo but you can make or buy threshold bars to deal with this

Yes you may be right but Ive decided to lose the insulation board and just insulate between joists really well.

If anyone put there thinks I'm wrong then please let me know :-)

unless the customer has specified that they dont want any step up i would proceed with the job and advise them what you need to do to properly lay the ufh

if they havent made and concerns to you i wouldnt worry about it almost every job where you are raising the floor ends up with a small variance in height which once laid is not a major issue generally

I'd go with the step........


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Does my builder need to insulate between the rafters with 120mm celotex or can he fit thick backer boards onto the rafters , fix the ufh mats and tile over that

Rafters, you mean joists..I would'nt be using backer boards directly over the joists...

Thanks for the reply whitebeam, what would you recommend the layers would be from the insulation upto the tiles with electric underfoor heating in between as well. Is there any way of avoiding the celotex between the joists as it is very expensive?

look around for chepaer brands..celotex and kingspan etc are all expensive but there are alterior products out there that do the same job

why are you filling the voids with celotex exactly ? is this a standard bathroom noty a new add on like a conversion that stipluates new insulation?

over board the joists with ply then lay 6mm cement boards i would lay cement boards direct to joists