Has anyone used this before?

Hi,

I'm installing UFH in three GF rooms, then laying LVT, and need to get them all at the same floor levels too. To do this I end up with needing to lay 2 different thicknesses of Floor grade PLY to satisfy the top flooring specifications...9mm & 6mm.

I'd prefer to only use one thickness, to get a better price but also to keep the thickness above the UFH the same across the whole GF. Having the same thickness should mean I get the same heat transfer times everywhere across the floor.

So I had an Idea that I could raise the UHF by 3mm by raising the top face of the joists by 3mm using this..

https://www.soundinsulation.ie/floor-soundproofing/25-acoustic-joist-strip.html

It's a non compressible floor joist strip for soundproofing, and seems to be a recognised system, but I don't car about the soundproofing but just the 3mm in height it gives me.

The idea being stick this down onto the joists...raising by 3mm...then insert the 25MM UFH insulation / routing panels...then the spreader plates...then pin the plates through the 3mm and into the joists..meaning that I can then lay 18mm T&G ply ...then the 6mm FG1 Ply for Karndean.

And I can do that across the entire floor so ending up with the same thermal performance and only buying one thickness of flooring PLY....

Does that work?

Just lay 9 everywhere ok? Not sure what the issue is specifically.
A 3mm difference in floor height could be taken up very éasily that's the problem

Cheers John,

I could lay 9mm everywhere but it will take longer for the UFH to heat up 9mm than 6mm....not by much but it will be longer....and it costs more to buy.

Also, adding 3mm to the joists will mean that all three rooms on the GF will have the UFH Insulation panels and pipework all at the same height.

Have you ever seen this stuff being used?

I'm not a pro so i haven't really seen much bring used, but when i rebuilt all what passed for sleeper walls under our house the joists were already so warped that it would have been impossible to level it it would have been a luxury not to have 3mm up, down and everywhere else. But in a new floor you'd probably hope to have better leveling.