Floor insulation?

Richard Roma

We’re currently in the process of a thorough renovation of our house. We’ll be getting the walls and ceilings insulated, and new windows and heating system along with various other improvements.

We had initially left the floor (suspended timber) insulation off the agenda as we’re very very tight for cash. We’re now considering begging, borrowing, or stealing (well probably not the last one) to pay for it. I know that heat rises, but I also understand that cold attacks the weakest point.

After chatting with the builder we’ve three options:

A. Do nothing;
B. Remove floor. 150 mm earth wool, new 18mm plywood;
C. Remove floor 70 mm earth wool, new 18 mm plywood.

Does anyone know whether not doing the insulation would lead to noticeable heat loss?

Thanks.

Bonzo Delaney

If your going down the road of removing the floor boards to fit insulation put as much insulation in as possible the labour costs are marginal instal a vapour barrier also and bring it 100 mm up the walls to be hidden by skirting.
There'll be a good difference in air transfer when it's done properly

jmBuildExt

had the same issue recently.
Budget didnt allow for it, so ended up with your option A but architect said it wasnt a major concern - we did external insulation, triple galzed windows and tpopeed up the attic. Given where the floor heating comes in that pyramid we came to our decision.
No practical comparison experience to offer you as a. the house is new to us. b. we only just had the work done, so hasnt been tested in the cold.

If you do go ahead and do it you should put a layer of draught proofing above the insulation. Edit: Yeah what he said.

BryanF

Installed two winters now. Very happy with the heat retention. Vapour barrier on warm side is essential. Run/tac a breathable felt under the joists, put insulation in between joists and tape/seal/tac vapour barrier over top of joists, then lay ply or timber floor.

Calahonda52

https://www.nsai.ie/S-R-54-2014-Code-of-Practice.aspx

I prefer alu faced rigid on supporting strips, fill gaps with expanded foam, then tape.

Making it 100% airtight around the perimeter is the most important, and most difficult piece to get right:
e.g. that joist running // to the wall about 4 inches or less out.

Lumen

Calahonda52 wrote: »

https://www.nsai.ie/S-R-54-2014-Code-of-Practice.aspx

Link doesn't work for me. This?

http://www.ili.co.uk/en/S.R.54-2014.pdf

Via

https://www.nsai.ie/about/news/publication-of-sr-542014-code-of-practice/