Screed drying time

[lotstolearn]

I've got some wet UFH being installed and My builder is planning to leave about 70mm of screed 1 week before doing the SLC. The floor will then be tiled. The screed is not a rapid setting mix and after a bit of basic research I'm struggling to find anywhere that suggests this is long enough for screed to go off. Have asked him about it a couple of times and he sounds confident and knows I'll have him back in a flash if there are any problems with the finish.

Can anyone think of a scenario where this works or give me any reassurance based on what I've said??

Thanks

Alex

[Wes]

Hi Alex,

Have a read of this http://www.netweber.co.uk/tile-fixing-p ... crete.html. Be sure to read right to the end

[steviejoiner74]

70mm of screed will take months to dry out sufficiently to tile on.
The basic rule of thumb is 1mm per day for drying so say 70 days in your case.

[Bill Darr]

We always work on 1mm per day up to 50mm and then 2 days per mm for the remainder - so 70mm would take about 90 days.

Temperature and ventilation etc will have a +/- effect though.

[Andrewgateway]

It would dry quicker with the ufh on.


Sent from my iPad using Tapatalk HD

[steviejoiner74]

It would dry quicker with the ufh on.


Sent from my iPad using Tapatalk HD

[Wes]

It would dry quicker with the ufh on.


Sent from my iPad using Tapatalk HD

It would, but it depends what type of screed it is as to force drying it. Normal sand cement screeds need to be allowed to cure before drying. If they are dried too quickly, they can crack and curl. They become extremely brittle. Even Gypsum based screeds need to be handled with care when force drying, particularly within the first 7 days or so..

Just saying lol

[Handyman in Sussex]

Also worth bearing in mind that the UFH will need to go through it's warm up process before you tile the floor... From memory, It should be increased 5 degrees per day from the current ambient temperature of the floor over a period of not less than 1 week, then run at full temp for a week and then warm down at 5 degrees per day over another week, then turned off. I'd allow the screed at least 3-4 weeks before doing this too. Speak to the screeder and the plumber to check on these times, or Wes probably knows the exact timing process too. I wouldn't take chances by not doing that....

[steviejoiner74]

Also worth bearing in mind that the UFH will need to go through it's warm up process before you tile the floor... From memory, It should be increased 5 degrees per day from the current ambient temperature of the floor over a period of not less than 1 week, then run at full temp for a week and then warm down at 5 degrees per day over another week, then turned off. I'd allow the screed at least 3-4 weeks before doing this too. Speak to the screeder and the plumber to check on these times, or Wes probably knows the exact timing process too. I wouldn't take chances by not doing that....

Spot on with that mate,it's the way I've seen it done countless times.
The guy suggesting banging on the underfloor heating hasn't got a scooby.

[Wes]

Wes probably knows the exact timing process too.

Nope, depends on what's getting fitted. I find this process chops and changes a lot between flooring types and brands.

Every time I come up against UFH, I go with what the particular product manufacturer tells me (via email or installation literature). A bit of 'covering my own a@se' as well as preferring to trust their R & D You probably know - if something ever goes wrong - who the first person is that gets the finger pointed at them? Obvious answer, us

[lotstolearn]

Thanks everyone. It will be 4 weeks next week and that's when he's planning to do the SLC.

I'll be back onsite this week to see how it's all looking and talk about the plan for running in the UFH which they haven't touched yet.