UFH Suspended wooden floor

[Lemna gibba]

We are planning a significant renovation to our house. Currently, we have a 1930s detached house that was significantly extended in the early 80s. We are removing internal walls to make an open plan living space, replacing a rear conservatory with an extension of similar size, and creating a front porch. On top of this we are going to improve the insulation (EWI throughout, triple glazed windows, and topping up the loft). The idea is to ditch the gas and replace this with a heat pump.

 

The 1980s part (kitchen) has a solid concrete floor. We plan to dig this out and insulate, so that we can run UFH across this together with new rear extension. In these room we'd want a stone floor, so UFH would be great. The 1930s part (labelled lounge and entrance hall) is a suspended timber floor. I think we have three options here.

 

1   Fill this with concrete, insulate and have a similar UFH system throughout. I'm not keen on this as I would worry about damp rising through the walls. I have no specific reason to be concerned, but have read horror stories. 

 

2  Keep the suspended floor, insulate between joints with kingspan and run floor panels with pre-cut spaces for the UFH pipes. Something like  in this link https://www.theunderfloorheatingstore.com/profloor-returns  Ideally we wanted to install bamboo flooring in this room. That would be fine from the point of view of the flooring, but I am concerned that with this solution we might end up with a not insubstantial amount of heat going to the space under the house. An alternative here would be to lay stone flooring throughout the ground floor. 

 

3  Just run UFH in the kitchen/rear extension and have radiators in the front of the house. Then we could insulate between rafters and use wood flooring. 

 

We're tending to the second option, and possibly with wood like ceramic flooring. I'd appreciate people's opinions. Our architect says that we should just do what we want, but we want the heating to be as efficient as possible.

 

[JohnMo]

Option 1, you include a DPC below.  An option maybe to apply DPC, insulation, the concrete.  Attach UFH pipes to the insulation.

 

2.  How deep are you floor joists and how much space below to ground.  A better option would be to insulate between with a dense Rockwool, more forgiving to install than PIR.  Use aluminium spacer plates to carry the pipes.

 

3.  Similar to 2.

 

 

[Lemna gibba]

Thanks for the quick reply. The questions about the floor joists and space to the ground are important. I won't know this until we start to take up the floor and I'm reluctant to do this until we get a bit further with the plans. I can see this is important, as if the joists are shallow then we're not going to have much to play with. I'll look into the the dense rockwool.

[JohnMo]

Something like Rockwool flexi.