Under Floor Heating on New Screed

[rj1884]

Good morning

I'm after a bit of advise if possible please. Went to see a job, newly built conservatory about 30m2 floor area. The customer was going to have wet UFH built into the screed initially but has since decided against this for one reason or another. She does however want electric UFH. Time is of the essence as is always the case.

The floor will be screed, sand and cement fibre screed.

What is the absolute earliest you guys would think about starting to fix the UFH system on this floor. I know the normal guidelines on times etc but just seeing if theres a way to do this earlier. The UFH will be ditra fixed over insulation boards. I've spoken to BAL who mentioned there green screed can be used after 24 hours however they don't recommend using it to fix the ditra heat directly to the screed. Have any of you guys fixed or would you recommend using green screed to fix the insulation board to the screed. I'm guessing that if I can use the green screed to do this I can then carry on as normal as in affect I would be fixing the UFH, tiles etc to the insulation board.

I apologise for the long winded explanation and thank you in advance for your comments.

 

[White Room]

Can it be stuck to the thermal boards which will be laid first.....

 

[rj1884]

Hi Whitebeam. My plan if suitable will be to fix the ditra on the insulation boards as you mentioned but I was sure if doing it to early would still cause problems.

 

[Stef]

You can use Weber set plus & AD250 add mix to make this a green screed, works out a fair bit cheaper than Bal.
I don't see how you can't fix to this although I haven't done it myself.
Alan (Ajax) is your man to ask on this..

 

[White Room]

Is it worth checking with Bal to see if green screed addy will stick to thermal boards....

 

[rj1884]

Hi. Thanks for your replies. I've spoken to Bal and they've said that their green screed can be used to fixed the boards which is a bonus I just wanted to see whether the more experience tilers have ever done this. My only worry would be is whether the screed drying would affect what's been laid on top of it but I suppose that's what green screed is designed to do.

 

[Ajax123]

Cant for the life of me think of a good reason to use an electric overlay system instead of an embedded wet system. Takes all sorts I suppose

 

[rj1884]

Exactly what I thought. Apparently there would be to much work involved based on where the boiler is currently situated. Would have been better though.

 

[Ajax123]

if they have a convenient radiator point they could connect straight into it with a simple 2 port manifold or a return temperature limit valve (I have these in my house) cant see what that has to do with the boiler position... still more work for your good self I guess so dont knock it. 🙂

 

[rj1884]

Exactly. I didn't really delve to much to be honest. I know you're the main man for screed advise, what would be you view on what I've explained.