Wood flooring on UFH screed

[Alex F]

Hello folks
I am trying to decide on flooring to use on the renovation of the farmhouse I am doing. It is for the ground floor which has new floor, DPC, insulation, slab, umderfloor heating and nicely level screed. Ideally I would like to use a reclaimed floor boards but appreciate there is some risk with movement particularly with the UFH. I have questions with regard to the installation:
1. Is it possible to glue floor boards direct to the screed with something like that Sika glue or is is necessary to lay either batten or or ply first which one then applies the floor to?
2. Does it make any difference (in terms of how one lays the floor (with or without battens/ply) whether one uses an engineered flooring (i.e. with ply pre-manufactured to the undersiden of the wood)?
I tring not to loose additional floor to ceiling height so hence and would rather avoid battens or ply under the floor boards. Moreover I am concerned regarding the Under floor heating conductivity as it will need to go through more wood or air before reaching the room and therefore presumably is less efficient then if the wood floor was direct layed on to the screed.
Advice and experience much appreciated - thank you.
Alex

 

[AMc]

Engineered boards where a 4-6mm solid wood board is laminated to a more stable ply base can look pretty good and will be cheaper, more stable and more efficient than ply with boards glued yourself. I've used this range and I'm very happy with the finish, though we're yet to fire up the heating.
http://www.vanillawoodfloors.co.uk/index.php?cPath=23_141

The advice from my underfloor heating installers is you should glue engineered board directly to the screed.
Battening would have needed to be fixed before the screed went in - you can't fix it in now for fear of hitting the pipes. If the battening were laid proud of the screed you'd create an insulating air gap which would seriously undermine the efficiency of the heating. The battens would also be very likely to move as they warmed and dried (or in the case of kiln dried maybe moistened and warmed).

I wouldn't try and create a floating floor from reclaimed wood, I would expect the boards to cup and bow splitting them and creating a shocking mess. We have relaid original floorboards over underfloor upstairs, but we notched the joists and installed the pipe and screed between the joists so the boards are firmly fixed to the joists. The screed upstairs is on;y 25mm vs 65mm in the solid floors downstairs.

 

[Alex F]

Thanks for that. Very helpful. I have 70MM over the actual pipes so would necessary it need to damage pipes. I was thinking I would glue the battens. Anyway I'll take your advice. Thanks. Alex