Discuss Screed & wet UFH issues. in the Tiling over Electric Underfloor Heating area at TilersForums.com

Sean Kelly

Sean Kelly

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I went to see a floor on Saturday. Roughly 12sqm of screed with wet UFH in a ground floor extension. The screed went down last week.


The surface of the screed was very rough and I could scrape up parts of it into my hand (very sandy). I could see and feel spongy insulation, as some of it was actually on the surface of the floor.


The wet UFH is actually part of the central heating. I believe the builders removed a radiator and connected the return and flow to the UFH pipes.


Nobody knows how deep the screed is, but the heating was turned on literally a few days after the screed had been laid. There is no ‘zoning’ and I believe the heating has been turned up high.


The heating is on a megaflow and several leaks appeared upstairs when the heating was turned on.


My advice was to carpet/vinyl or lay a wooden floor.


Questions:

  1. Is this form of UFH normal?
  2. Can anything be done with the screed?

I think I might know the answers to both questions, but I thought I should put it out there. What makes matters worse is that the new extension is part of a lounge. The old part of the lounge does not have UFH. The couple want 60x60 tiles and they want the grout lines to line up with the tiles in the hall and kitchen (also 60x60)....the old tiles were laid about 5 years ago. Therefore I am not able to span a tile across a heated and unheated floor.

Insulation showing:
20171202_135920.jpg

Sandy top:
20171202_135934.jpg 20171202_135945.jpg 20171202_140027.jpg

New screed (left), flat old screed (right)
20171202_141728.jpg
 
Chalker

Chalker

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Walk away mate!
Having no manifold, or blending valve. Will make the pipework run at the same temp as the rads. This could be up to 80 degrees!! It will ruin any floor that is laid.
 
Sean Kelly

Sean Kelly

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  • Thread Starter Thread Starter
  • #6
Thought you would all say that.

The other complication is that the customer is my GP and my neighbour. I have told them straight, that it is not suitable for tiling onto but I would investigate if anything could be salvaged from the situation.
 
A

Ajax123

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Ok. I see your dilemma. In terms of the screed it is clearly badly laid and poorly mixed and compacted. It is also of indeterminate depth which means as it is it should not be tiled. the insulation is the bit that makes it most difficult as there are no thin screed systems that can be laid at the sorts of depths you would need. Dealing with poor compaction and poor mixing even with very low cement contents is doable but only if sufficient depth is available.
 
I

Italy

it is possible to execute it.
but then, you should change your doctor and home.
I would explain the situation to the doctor well.
usually doctors understand.
 
A

Ajax123

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If you could excavate two or three small samples to find out how deep it is if it is sufficiently deep you could use a stabilising epoxy such as PSRS from Ardex or PHS from Flowcrete to stabilise and harden the screed. It would then be suitable for tiling. If it is not deep enough then you might as well call it a day and walk away. Im sure regardless of the fact he is your doctor and your neighbour he would rather have a proper job done. I assume he has paid for the screed in which case he can probably kiss that money goodbye...
 
LEE MAC

LEE MAC

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The cheapest solution to this problem is to pull the screed up (2-3hours work) get a competent plumber/heating engineer involved, rescreed and tile. Job done!
 
D

Dumbo

It'll be alright it's been done by a builder you can trust them
 

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