Do I need to latex over UFH pipe prior to laying ditra matting?

[Eileen Dover]

Hi all,
I have recently had JK Underfloor heating route out my existing screed floor with a 15mm groove to take the underfloor heating pipe. They have done a great job but my tiler is worried about sticking the ditra matting straight over the top without latexing it first to take up any small voids. Is this necessary as this is going to add a lot of cost? The tiles are 800mm square so very large tiles and with the ditra matting as well I would have thought it would be fine but I would be glad of your expert advice!
Many thanks

 

[Waluigi]

Latex

 

[peteablard]

I've always gone over them with SLC. Not familiar with this system but them ones I have tiled have always left the pipes a few mm proud.

 

[Eileen Dover]

Hello Peteablard, thank you for your advice. The pipes are not proud so the ditra would run straight over, and the ditra adhesive would fill some gaps. I have attached a couple of images for your info. Just dont want to pay for latexing if its not really necessary as it is gonna cost an extra £1000-£1500! Got about 80sqm to do!

 

[Old Mod]

I’m no heating engineer, but that’s an awfully concentrated run of pipes in the centre and to the left side!
Surely even heat distribution will not be possible like that.
I’d want it latex’d too, with the system charged cold to 5-6 bar the pipes will expand, leaving room for expansion and contraction below the finished floor, increasing your chances of a successful install, it will also enable a far better transfer of heat to your finished floor.
If latex’d, an antifracture Mat would suffice instead of ditra. This will enable a lower build up and will be more cost effective.
@Chalker may be able to advise on the ufh set up.
Are your tiles 10mm plus porcelain or thin tile?

I can see that this is a large investment on your part and I can appreciate you don’t want to spend money unless it’s absolutely necessary, however, have you considered the cost if your install fails?

 

[Waluigi]

On the plus side, you won’t tread on the cat laying at the bottom of the stairs 🙂

Definitely latex. It’s not even belt and braces, it’s a must.

Your Tiler has already raised his concerns.

Edit: I know the system here and the sales rep does a good job of explaining why having no insulation on older properties isn’t the end of the world. I’m not 100% convinced.

 

[GoneGuy]

I would ensure all ufh pipes or cables are encased.

 

[Spare Tool]

I've never seen anything like it...screed chased out to house the pipes is a new one on me, and what's with the big clusters of pipes, got to be latex then uncouple, and not just a thin skim either, I'd advise around 6-10mm of fiber reinforced leveler over that lot

 

[Flintstone]

Something doesn't seem quite right to me.

 

[Dumbo]

Surely with that concentration of heat pipes in front of the radiator wouldn't it be best to overboard the floor with hardie backer before tiling . I wouldn't be comfortable tiling on that.

 

[Dumbo]

I've had a better look . That's not the worst bit is it .