Im new to this board and would be very grateful if you could help me with an issue I have. We have recently had a garage conversion carried out and the final part of this was to lay the underfloor heating by way of 3 heat mats connected to a thermostat with a floor probe. The builders have finished this work but the screed over the floor mats has severely cracked over the last couple of days and I would like some other opinions as to how the work was completed. The levels of flooring are as follows : 1) The original concrete garage floor was covered with bitumen 2) Then a damp proof membrane 3) Then a sand/cement screed over boards of insulation 4) Chipboard 5) Contact adhesive sprayed on to chipboard 6) Insulation mats stuck down then heat mats stuck on to the insulation boards http://www.theunderfloorheatingstore.co ... 4542576158 7) a laytex screed applied over the heatmats to a depth where you can still make out the pattern of the wires. http://www.qvsdirect.com/_search.php?pa ... eating+mat <http://www.qvsdirect.com/_search.php?page=1&q=stiebel+eltron+heating+mat> http://www.wickes.co.uk/Latex-Floor-Lev ... nvt/224669 As I mentioned at the beginning there are many large cracks on top of the screed, which has been down for over 2 weeks now.. When speaking to the builders they have recommended placing 6mm ply over the heatmats to cure the problem and then lay the floor covering on top of that. To me this sounds like a bodge which will not cure the problem and will absorb the heat from the mats. FYI - Half the room will have carpet and the other half will have either a laminate floor or something like Karnde (posh lino) ;-) Any help would be gratefully received.. thanks
could be a few things at fault here. 1st the compound used is total rubbish. 2nd You have chipboard on top of the concrete slab? Is there a moister barrier between the chipboard and concrete? how long was it left to dry and how deep is it? 3rd- Its sounds like you have ended up with a floating floor that you cant screed over. Well you defo cant with wickes compound but you may be o.k with a flex compound. Not recommened tho. have you spoke to the manufactorer about the issue?
Thanks for the reply , I don't think that there is a moisture barrier but a lot if the work was done whilst I was at work. Which manufacturer would u recommend to talk to ?? Is there a way they can remove the cracked screed from the mats and redo it ??
Any pictures m8, how deep was the screed, how long did they wait between stages, was this done during that bad weather over xmas? Brian
your last picture, Can you get another picture more end on so i can see how they have built up the layers.
I can take another one this evening. FYI - the layers that are visible are 1) Screed 2) Heat mat 3) XPS Standard board http://www.theunderfloorheatingstore.co ... 4529358221 4)Chipboard
could do with a larger picture. How is the chipboard fastened down? Is the xps board a solid board or soft?
The xps is a soft board , the chipboard is a t&c type so guess it just slotted together but I wasn't here when it was fitted. The ufh was off when the screed was applied, and has been on since, but not for long . Switched on by the builder on gull though !!!!
Let me just get this correct. 1st - The xps board is a soft board? The heating mat is layed onto the xps board, then the levelling compound is applied to the top of xps (soft board) and the heating mats? 2nd - The above materials are applied over a 'floating' chipboard base, the chipboard is floating direct over a new concrete slab with no DPM sheet between the two also?
well..... ye you have issues but you already know that. 1st- you can not apply a smoothing compound over a surface that has less compresive strength than the product itself. In English- The subfloor (xps) is to soft to have a smoothing compound on top (going on the fact you have told me it is soft). If you apply a compound that is more dense over a softer product it will crack and break up. 2nd- you should not lay a leveling compound onto a floating floor. Your chipboard (by what you say) is floating. Also as it has no DPM and the concrete under it has not been allowed to dry (1mm per day on adverage) the chipboard will take on moister and will warp, crumble etc. I dont think this is your issue but is the next issue you may have. There are a few more issues than this but i would need to inspect to prove them. I have not read the instructions on this xps stuff but if they say you can screed over it and it is 'soft' then they are wrong. Let us know how you get on, if you need someone to come out to do a full report on your issues then give me a shout and i will arrange for you. The report will stand up in a court of law if you need to go that far. Im sure you will get this sorted tho.
