Bitumen to stick floorboards over underfloor heating

[bbw1973]

Hi all,

After reading many threads and picking up some really useful advice in recent months, I've finally taken the plunge and joined up! I'm hoping someone can help with the following....

We have a wet underfloor heating system that was recently installed. It has been screeded and my builder has put a levelling compound over the top (a little early for my liking, as I wanted the screed to have as much time as possible to cure). I'll just have to hope that it is sufficiently cured.

Anyway, my main concern is the flooring. We're having timber floorboards put down, and the builder wants to use bitumen to secure them. He says glue is far too expensive. I'm obviously pleased he's thinking about saving money, but extremely concerned about using bitumen. I know nothing about the stuff, but just looking at it is enough to make me wonder whether it's actually safe to use over underfloor heating (vapours, fumes etc etc). So, can anyone advise on this please? Also, if it does turn out to be a very bad idea to use bitumen, are there any other recognised, tried and tested safe products out there please?

Thanks a lot!

 

[WoodYouLike]

Ouch: bitumen is officially no longer allowed to be used inside and you are absolutely right to worry about fumes etc.

You're much better of using flexible adhesives like Sika or Mapei P990 in this case - could be a bit more expensive than the old bitumen but much more preferable and healthy!

(Are you sure you want to use your builder to install your floor now he's come up with this "solution"?)

 

[mac391]

I've never liked the idea of laying one screed on top of another by different companies, builders etc. The important thing is matching the screed with the original. Some pumped screeds over underfloor heating are all that is required and flat enough to lay new flooring directly to, without the need of another levelling screed on top, which could be the wrong one!!

Too many questions arise like, Is the original screed traditional sand/cement or gypsum based? Do i prime the new screed? if so, which primer? Should i use water-based, acrylic or latex screed no top? which adhesive do i use, etc etc..

It should be straight forward but for some reason this industry isn't.

Drying time is also important so i would leave your screed for a while to make sure it's correct and works as it should.

Ask about the screed used to cover your heating loops and about the screed your builder placed on top before you proceed. You could always test it for moisture with a hygrometer if you want to move on with it.

If all is well then f-ball make a solvent free, underfloor heating adhesive for wood flooring called B93 www.f-ball.co.uk The site also has helpful screed info.

Bitumen?? NO

Good luck..