Insulating 2" gap between houses . . .

[Odyssy]

1910 terrace, brick built with a narrow gap (approx 1.5" - 2") between ours and next door. The gap is sealed with mortar at the front, lead flashing at roof height front and back (except where both chimney stacks are), but open gap at rear.

SWMBO suggested having this cavity insulated to retain heat. I'm dubious that it could be done, (without drilling internal walls) the space is 8.3m deep and up to 10m high.

We had a engineers survey done 15 years ago and he suggested it was advisable to leave the gap open to allow ventilation.

Any thoughts appreciated.

TIA - Alastair

 

[Raize]

1910 terrace, brick built with a narrow gap (approx 1.5" - 2") between ours and next door. The gap is sealed with mortar at the front, lead flashing at roof height front and back (except where both chimney stacks are), but open gap at rear.

SWMBO suggested having this cavity insulated to retain heat. I'm dubious that it could be done, (without drilling internal walls) the space is 8.3m deep and up to 10m high.

We had a engineers survey done 15 years ago and he suggested it was advisable to leave the gap open to allow ventilation.

Any thoughts appreciated.

TIA - Alastair

That gap is, in essence, a party wall. Is there a specific reason you want to insulate it?

If it's for thermal reasons, then it really won't make much of a difference. You could get blown cavity insulation in there, but a better solution would be to insulate internally with a insulated backed plasterboard, something like Celotex's PL4000 or Kingspan K17 / K18.

If it for accoustic reasons, insulating that gap won't help. You'd need to construct an acoustic partition, internally.

 

[Deluks]

Are there any signs of vents or airbricks in either side (within the gap)

 

[Odyssy]

Thanks - the reason ? "SWMBO suggested having this cavity insulated to retain heat."

TBH I don't think it would make a deal of difference, but to keep the peace I told her I would enquire, so I'm enquiring.

I thought that blown cavity insulation was a possibility, but not sure if it was do-able without drilling through internal walls, which is not an option.

The next stage is to ask a contractor for an opinion - fairly sure I know what the answer will be . . . "Of course we can do it - it will save you £xx a year. And it will only cost you £xxx"

No vents or airbricks on either side.

It's not a particularly cold house considering they're solid walls, but I'm topping up the roof insulation and generally making it more thermally efficient.

A

 

[mointainwalker]

I think the existing arrangement is sensible. Measures have been taken to prevent/minimise water-ingress and one side left for ventilation if anything fails.

Think of the problems if the fill were to get wet and your neighbours complained about damp walls.