Laying over underfloor heating??

[beaky]

Hi Guys,
Ive got a friend who's laying over water based underfloor heating, he has a concrete base, then his underfloor heating is approx 30mm would he have to lay some plywood over this or is he better to use a levelling compund or something else??

Thanks

[GazTech]

Is the UFH buried in the 30mm screed ?

[beaky]

yes it is

[DEtileD]

I think I understand what your asking....Well all i will say is that is a lot of leveller. Have you looked into products like the schluter Bekotec? Will save a lot of materials, keeps everything in place and is easy to work with.
D

[GazTech]

No sense in overlaying in plywood, just be sure to use powdered flexible adhesives and flexible grouts. you must also allow the screed to cure properly before tiling, one inch per week, is the drying time. After you have finished tiling, the customer must wait 2 weeks before running the UFH, and it should be increased by 5 degrees per day till max, and the same down to off, this gives the addy and grout chance to accustomise to the temerature changes......Gaz

[DEtileD]

or maybe i don't understand
D

[beaky]

brilliant, thanks gaz

[GazTech]

A solid bed of adhesive is required to maximise the heated effect, anthing you are unsure of then plz ask,
....lets have some pictures please we like them....Gaz

[wetdec]

As Gaz has said.......

You will do well to lay a membrane such as Durabase CI to prevent cracking of tiles due to expansion and contraction of the screed. Fix the durabase using a flexible adhesive to the existing screed then tile over the matting. A fleece surface on the screed side of the mat absorbs any latteral movement so preventing cracks traveling through to the tiles fixed to a mesh on the upper serface.

A membrane should be used when tiling over wood floors, new screeds and heated screeds to prevent latteral cracking of surface coverings.

More info is available here for you, Dura-ci uncoupling membrane


Tiler

..

[brian c]

good advise Gaz m8.

[Mike]

in case you don't know these are old posts. job will be well finished by now