Discuss Sub Floor cracks with UFH in the Tiling Forum | Tile Advice area at TilersForums.com

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Hi everyone,

I had my floor ripped up after a leak two years ago and wanted to get UFH heating system in my kitchen. The kitchen units were not removed but the floor around was back to original concrete base (house circa 1880). see pictures

I wanted to maintain the original height of the floor so was advised to have a DPM then 60mm construction board bonded to the floor. electric UFH heating was then placed on the board and a latex levelling compound over the top.

Tiles were laid about three days later and the UFH heating commissioned at least six weeks later but not used consistently until the autumn.
in the spring of the following year I noticed some tiles sounded hollow and had some of them refitted but i noticed almost immediately other tiles were working loose.

After many calls to the tiler which remained unanswered i ripped up the tiles and noticed many cracks in the levelling compound and the floor see attached pictures.

There looks to be too little expansion gap between leveller and wall? and the cracks (the big ones) seem to have started in the middle of the room (possibly weakest point) could this be the problem there is no expansion gap between the insulating construction boards and the walls either

I have resigned myself that it is all coming up and want your advice on how to go about redoing it so it will not fail!

any help much appreciated!

thanks in advance

Rick
B2875831-E430-4207-9153-A087879CBF22.jpeg
0BDE3670-E41B-40F5-80AC-3AD65209C6C1.jpeg776EA2A8-271B-4160-93BC-C7F413B2B133.jpegF1FCDF8D-65B1-4FB3-A365-DBB6A45A2309.jpeg61AA2979-E0CC-440A-B831-9C29B3D53954.jpeg776EA2A8-271B-4160-93BC-C7F413B2B133.jpegF1FCDF8D-65B1-4FB3-A365-DBB6A45A2309.jpeg61AA2979-E0CC-440A-B831-9C29B3D53954.jpeg
 

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jcrtiling

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When you commissioned floor did you raise the heat slowly and when you did this was your heating on 24hours a day.
 
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When you commissioned floor did you raise the heat slowly and when you did this was your heating on 24hours a day.
it was set to be at 24 degrees and a minimum of 17 degrees when commissioned the thermostat said the floor was at 22 degrees ambient. the floor heating wasn't on 24 hours.
 

JulianSidney

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I'd be more concerned how and what the construction board was and how it was treated when being bonded to dpm and how and what slc was and what prep was done to the board and ufh wires.
To me it looks like the construction board wasn't bonded correctly.
 

widler

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Like julian says , which boards were used, were they stuck down, have you can pics of the floor from old floor to DPM, boards and matting being laid
 
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I'd be more concerned how and what the construction board was and how it was treated when being bonded to dpm and how and what slc was and what prep was done to the board and ufh wires.
To me it looks like the construction board wasn't bonded correctly.
Hi all thanks for your expertise, I think the boards are delta 60mm construction, they were apparently bonded to the concrete DPM. The original floor was ripped out due to a water leak and i am wondering if the concrete was still damp.
 

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In the first picture there appears to be a radiating crack. This looks indicative of the delta board blowing from the DPM.
 
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Ive just started another thread on this without realising Rick had beaten me to it! My initial thoughts on seeing the floor was that there are two things happening here to compound the problem. Thermal shock would cause the tiles to debond so cleanly an over the entire floor but more concerning is the movement in the boards themselves. I think the bond between the concrete slab and delta boards has failed
 

jcrtiling

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To be honest I think you best take one up and have a look, ,, oh then report back
 

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