Hi, Could i ask some expert opinions on our current project... At first floor level in our latest project we have - Timber floor joists with two timber flooring types ontop - Original Portion of the house - 1950's T&G floorboards, New 3 storey extension - New timber floor joists with 22mm caber floor on top. Ontop of the entire first floors we're planning to install Wet UFH with wundatrade wundatherm boards which are 20mm xps aluminium backed dense pre grooved boards housing the pipework. Original plan was to go straight ontop of these pipe boards with a high quality Amtico Click, however i'm concerned with the heat levels and the click. New plan is to ply out the floorboards and caber floor with ply - likely 9mm screwed and glued. Then install the wundatherm boards, install the pipework and cast 10mm of self leveller over the top - finally finishing with Amtico LVT. I've looked at Mapei 3240 Renovation screed which has fibres and also various Ultra (Instarmac) products with fibre reinforcement. I'm just a little concerned about the potential for a little flex in the timber joists and how much flex the levelling screed could take? Both reps from both companies would seem to think it would be fine at 10mm thickness, but i don't trust warranties out of previous experience. Main concern would be that if the levelling screed cracked and broke up at all, the lvt stuck would of course be compromised and a repair would be incredibly difficult! I've considered adding rendering mesh to the boards before screeding ontop to add even more strength... Any tips or comments would be amazing! Thanks in advance Tom
If I was you I would get a written specification from Wunda and Amtico. There’s so many reasons why this system won’t work. You need to do it by the book and that is usually pretty impossible with so many systems/trades involved.
Thanks for your reply. The advice from Wunda is that it is fine to self level over the top of the wundatherm boards. They recommend Mapei or Instarmac products to do it. The aluminium boards must be primed however first. Could you elaborate on the things I may not have taken into consideration?
Is it fine to stick Amtico to? I don’t think I’ve ever seen one of these systems I would Be happy to stick a 2.5mm lvt on. Prefer a laminate or floated engineered wood. If Amtico say it ok and wunda say that’s how you prep it thats great But get it in writing
Well the Amtico would be stuck to the self leveller with heat resistant adhesive due to the UFH below. I was originally going for a click LVT or click laminate floor directly over the aluminium wundatherm boards, but a few people have mentioned that click flooring directly over UFH pipes wouldn’t be a great idea?
I’d use a MS flexible adhesive to bond the XPS down, then use the sane adhesive over the top of the XPS then use a product called uni board 4mm, then install the click, any further advice please dm me
A thick floated floor with a low tog rating will be fine. Clic lvt is ok with ufh but not with direct sunlight. Although some good quality rigid clicks are fine. Bit of a minefield on quality and clic systems though. Also save you a lot of money having a floated floor
Speaking to Amtico today about this system and it is a recommended ufh system. As long as there’s not too much deflection in the timber subfloor and the panels are fully bonded down as it says prim grip, 10mm renovation screed and stick to that. I’m still a bit dubious. It does also say you can bond solid oak directly to the panel! Can’t see that working! Like I say I’ve never actually seen one that’s been installed good enough. Usually the panels are half stuck and the pipes are sticking out of the grooves. If you have a good plumber you might be ok
Thanks a lot merit, it’s just what is defined as not much deflection… the floors are about as solid as a timber suspended floor could ever be, and we’re then reinforcing them further with ply ontop. I’ve found a new product made by Uzin which is a fleece mesh. Very expensive, but might be worth looking at for additional reinforcement.
