Looking for some help deciding if Spray Foam insulation underfloor is going to be a good or bad thing for my house.
The 100 yr old wooden floor is always cold so some form of insulation would be good but I hear horror stories about this kind of insulation in lofts where lack of airflow has allowed damp to seriously damage the joists.
Would the risks be the same for subfloor ?
I have an installer, Q-Bot, quoting for the work but clearly it’s in their interests
To sell the product.
Advice much appreciated, thanks
Just watched a video with that question and it says. That even with insulation. Floor is still going to be cold to your feetOriginally Posted by eddie1
His example is. Body temp is 98 degrees and if your house temp is set to 75. The floors will only reach a 75 degree temp. So compared to your 98 D body temp. Floor is still going to feel cold
https://www.youtube.com/watch?v=cFXZ...rawlSpaceNinja
DON
Useful video thanks
Rockwool would seem to be the better option
I’m going to guess that it’s a late Victorian or Edwardian house with a small void under the ground floor joists. There are a number of pertinent factors which would include surrounding ground levels, whether the house is mid-terrace, end-terrace/semi detached or detached (as that will affect the number of ventilation airbricks), are you on top of a hill or in a flood plain, what subsoil, etc...
Generally, underfloor voids can be quite humid and sometimes very damp. I would be wary about anything that might impede air flow unless it’s an unusually dry underfloor area.
As a thought, do you have old square-edge floorboards? If so it’s likely that cold draughts will be coming through every gap where they have shrunk. Fixing that might help considerably.
Hi yes it’s an Edwardian semi with aprox 2 foot subfloor space with air bricks around but built over London clay.
Floor boards are not original and in part covered with laminate.
Always seemed that a lot of heat gets lost through the Floor / or cold rises
Up From it which is why I was considering insulation.
Can’t do the external walls as not cavity
In the past, I've accessed the void beneath the floor and cut and installed Kingspan or equivalent between the joists simply held in place with small turn lock battens screwed to the bottoms of the joists.
Thanks Reggie
My crawl space too small to do that
But was your house Warmer for it ?
That would be the preferred option (for me) TBH.
When you look long into an abyss, the abyss looks long into you.........
Having done this quite a few houses, Celotex RIB can be cut to fit between the joists then a gap filler used on the floorboards. Lose the laminate. You will maintain the airflow and prevent mould growth.
The gap filler is called StopGap, not an insulator, just stops draughts.
If you use celotex then wear a mask, goggles and a tyvex coverall. You’ll thank me if you decide to do that.
You say you have approx 2 foot void ? Unless you're Billy Bunters brother, that's huge !!! 😆 And yes, the difference was quite unbelievable as were the fuel bills difference over the coming years.
Thanks all very
Helpful
My brother in law used something like chicken wire to create baskets between the joists into which he laid the insulation. A lot of work but he did this when he had the house gutted. He also installed under floor heating which did feel under foot.
I was going to suggest garden netting draped between the joists
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