has anyone ever come across

[cam_low]

a plumber using what appears to be pallets of SLC to encapsulate wet ufh pipes ?

I dont know the brand of SLC used yet. still awaiting reply. all I do know is that is was £1500 to do a 10m2 40mm in depth.

What does this mean for drying times and commisoning the heating. Anything I should be made aware of ?

cheers folks

 

[DP Tiling]

Most fibre reinforced SLC can go up to 50mm in one hit these days so thickness of bed isn't likely an issue. What concerns me is if I remember correctly it says in bs 5385 that wet system UFH has to be in a min of 75mm screed, due to the flow temperature through the pipes - too close to the surface could cause the tiles to get too hot and can cause tenting or lifting of the tiles. I could be wrong but I don't think I am. Ajax is the man for this methinks. He is indeed a fountain of knowledge

 

[J Sid]

British & European standards

Several standards cover the different areas of underfloor heating, and are detailed below:
•Wet systems fall under the British standard BS.EN 1264, Parts 1 to 4. Part 2 of the legislation states that the maximum comfortable temperature underfoot is 29°C; while part 4 specifies the allowance in wet rooms of a maximum floor temperature of 33°C, and 35°C for a one metre perimeter zone. The standard also sets out a limit of 1.5 TOGs for any floor coverings.
•Most types of flooring are comfortable within this temperature range; basic vinyl flooring and lino can withstand a surface temperature of 27°C, while heavy duty plastic sheeting can tolerate a 29°C surface temperature.

 

[cam_low]

thanks so far @Ajax can you help?

I have just had a confirmation of the floor. concrete base, 18mm insulation fibre board, wet ufh and 20mm screed.

any thoughts ?

 

[Ajax123]

British & European standards

Several standards cover the different areas of underfloor heating, and are detailed below:
•Wet systems fall under the British standard BS.EN 1264, Parts 1 to 4. Part 2 of the legislation states that the maximum comfortable temperature underfoot is 29°C; while part 4 specifies the allowance in wet rooms of a maximum floor temperature of 33°C, and 35°C for a one metre perimeter zone. The standard also sets out a limit of 1.5 TOGs for any floor coverings.
•Most types of flooring are comfortable within this temperature range; basic vinyl flooring and lino can withstand a surface temperature of 27°C, while heavy duty plastic sheeting can tolerate a 29°C surface temperature.

Bear in mind that British standards are onl y guidelines and not legislation. You are able to step outside of the British standards and use what are termed proprietary systems. Additionally some systems are covered under Bba certification or cstb or Astm standards.

 

[Ajax123]

I have never seen a wet underfloor heating system encapsulated with standard self levelling compounds. However there are a few bagged materials such as our sure flow product which mix and act like slc but are actually thick screeds

One of the issues using a standard leveller is the drying shrinkage which could lead to cracking and curling. Not a good idea in my opinion and hellish expensive to do. However if it performs "structurally" speaking and you follow all the standard rules ie. Dry it, sand it, heat it, fix it (assuming it cracks) prime it then I can't see any reason to worry. I would probably go with ditra as a back stop though.

 

[cam_low]

Should I set it at 40mm or tiles straight onto the 20mm

 

[Ajax123]

I don't think it'll make much difference from the screed point of view. There might be a few hot spots at 20 mm though which might affect your adhesive. It'd need jointing properly.... My guess is the screed won't be jointed.....

 

[Sean SML Tiling]

The schluter bekotek system only requires 8mm of screed above the system so like ajax said the screed won't make a huge difference. I personally would go with ditra and proper expansion joints.