Hi all, I'm planning to install electric underfloor heating (Warmup StickyMat) in a timber garden cabin and am looking for a bit of reassurance that what I'm planning will do the trick. Surprisingly (or maybe worryingly!), I've not been able to find anyone else online who's done it this way! The cabin sits on a concrete slab with 95mm timber bearers. We have already laid 30mm Celotex followed by 65mm sand/cement screed. The plan is to lay the electric mat directly on to the screed, then tiles (ceramic) straight on top. I'm thinking about priming the screed (e.g. Mapei Primer G), although not completely sure if this is necessary with the StickyMat system). I'll be using a flexible adhesive (e.g. Mapei Rapid-Set). The electric mat instructions advise to only use tile backer boards and as mentioned, I can't seem to find anyone online who has done it any other way. Any advice would be appreciated!
These products should be suitable but check with Warmup first: https://www.theunderfloorheatingstore.com/ultraplan-renovation-levelling-compound-25kg https://www.theunderfloorheatingstore.com/mapeker-rapid-set-flexible-tile-adhesive-20kg
An an update, we ended up doing it more or less as I outlined above. Could have done with a bit more primer as the top of the screed was a little loose in places which didn't help with sticking the mat down. Had more electric matting than necessary which was a slight issue but we made it work. Finally got around to wiring it up the other day and have enjoyed a couple of days of warm floors. Does take a couple of hours to get the room up to temperature (perhaps would be quicker with backer boards) but then the screed probably acts as a bit of a heat store so who knows.