Hot Water Under Floor Heating On A Sand Cement Screed

[Perry]

one of those clever guys who know everything :furious3:

 

[Leatherface]

Guys - to do the job properly - first the screed should be allowed to dry out naturally - dependant upon conditions. Once dry the underfloor heating should be switched on and gradually brought up to maximum operating temperature - . Leave on once max temp has been reached for a couple of days , then allow to cool down prior to tiling. The reason for switching the heating on first is to allow for any initial expansion and cracking of the screed due to the heat.
Once tiles have been fixed again leave heating off for a couple of weeks, then again heating should be switched on and gradually brought up to maximum temp again.
Sounds a drawn out process, but a safe one. This is what I always advise and have never had any tiles crack or lift.

 

[DHTiling]

Spot on advise......works every time.........

 

[White Room]

If I was laying screed on under floor heating, It be would ready mixed with fibres mixed in for strength and leave to cure, never seen covering over screed, but 60mm have even layed 75mm,and your'll need more than a couple weeks. No heating until screed has cured notch up slowly, otherwise cracking will happen. They say concrete reaches its maximum strength after 30 years

 

[Leatherface]

Cheers Dave - will try to be as helpful as I can, where I can. Fair play ti IM Tiles for asking - have seen a few jobs done where tilers have not asked and carried on regardless with disasterous and costly results

 

[DHTiling]

And it will still happen....but hopefully we can show some the errors of there ways so to speak......keep it up mate...

 

[Leatherface]

As far as I know the advice is allow one day per mm of screed for drying out again dependant upon conditions. Please correct me if I am wrong

 

[DHTiling]

its about that..but the average screed is 30 days or so..but there are products that can be used to tile onto screeds as soon as they can be walked on..Like ditra mat.. it is a vapour equalising membrane and great for fastrack installations...and bal do a green-screed adhesive..........

 

[White Room]

As far as I know the advice is allow one day per mm of screed for drying out again dependant upon conditions. Please correct me if I am wrong

Same as, but no nobody wants to wait that long, with solid plastering you would have to wait 6 weeks, could'nt do that now

 

[Leatherface]

Yes I was using Ditra Matting on a job in Cheltenham last week - didn't know it was suitable for underfloor heating though ?
Bal Green Screed adhesive is extortionate in price.
Also if you are able to have an input into the screeding process, which is usually unlikely, some manufacturers do a Fasttrack screed that can be tiled onto in a week or so - Mapei are one such supplier