Can anyone recommend a reliable installer of cavity wall insulation in Cumbria? Our 70s house in bloody freezing ….

There is a good reason why there is a cavity.
https://www.which.co.uk/reviews/insulation/article/cavity-wall-insulation/cavity-wall-insulation-damp-problems

Problems with cavity-wall insulation, caused by wind-driven rain

Damp Interior Walls

Filling the cavity in a house in Cumbria is only going to lead to damp.

External insulation is a possible option.

Check its suitable for your area, it’s not recommended if you regularly get driving rain that would soak through the outer bricks and saturate the insulation, might explain why you can’t find one in Cumbria!

[edit: Paton beat me by 27 seconds]

https://www.bbc.co.uk/news/uk-wales-42165358

This is e-on propaganda but it gives an idea of what external insulation is

more info

Thanks for that. I thought that EPS beads didn’t conduct the damp, but you maybe right about the lack of installers in Cumbria, I suppose …..

Better to insulate either outside or inside the house. We dry-lined a cold bedroom with Kingspan and foam-backed plasterboard and the effect was amazing. It’s the warmest room in the house now.

Im in Cumbria, and have had wool cavity wall injected. Works a treat, no damp.. Not sure who did it though, was done through a grant scheme some years ago.

Im in Cumbria, and have had wool cavity wall injected. Works a treat, no damp.

I’m in Wales, and have had wool cavity wall injected. Just had to pay to get it out again (16 years later) because of damp.

I would say don’t do it.

Lots of places around here have had the external insulation on some sort of grant. Seems to be OK, but I’d be concerned about the long-term durability of it.

@leebaxter – do you mean ‘mineral wool’? It claims not to transmit water across the cavity …

Ours was mineral wool.

It claims not to transmit water across the cavity …

That claim is, indeed, made. Turned out it was wrong, though.

Cost me £3k to get the insulation out of my cavity walls. West Highlands so probably similar weather to you. I’ll take draughty and dry over damp.

All of the cavity insulation allow water to cross the cavity. The cavity is there as a physical barrier to stop water reaching the inner wall, not to stuff full of insulation. Even on new builds there’s still a gap. Cold spots can also be an issue if the insulation doesn’t fully fill the cavity which is highly likely. This can cause condensation on the inner wall. It’s very easy to put in, lots of people don’t have issues but if you do it’s very difficult to get out again.

Here on the Sarf Coast (Eastbourne) we’ve got cavity wall insulation installed by the previous occupants of our 50’s bungalow.  One wall gets hit with the full force of the westerly winter storms and until we had our conservatory built against that wall it was always damp.  So even in a “safe” area I’d question its validity.

The least exposed and used room in the house suffers condensation issues unless the rad is on max and the windows left to vent as well.

Cavities designed are to prevent damp penetrating walls, to fill them with anything is a poor idea. Either use rock wool and render on the outside, or insulate and dry line the inside. Leave the cavity alone.

Avoid like the plague…

1) Insulation slumps over time leading to cold spots at high level leading to condensation / black spot mould occurring at the tops of walls.

2) Mineral wool or similar in the cavity will snag on wall ties leaving them frequently damp for prolonged periods of time, resulting in accelerated wall tie failure.

3) Over time mortar, sand, brick dust etc all break down & can get trapped on full-fill insulation, leaving a damp soggy mass in contact with the inner skin of brickwork with resultant damp transfer.

Crikey. That’s me told.

Insulation of the right kind works fine in a well designed new build, as long as there is an air gap. Foil faced PIR. Retro fitting insulation in an existing house is not really an option.

at about 5:25 in

Cavity walls and solid walls are two different things, but this (solid wall example) gives an idea of why external insulation is possibly a better option.

External insulation allows you to install a decent thickness off whatever system which will give significant benefits. However you will need to work out how to deal with reveals (to Windows and doors) and possibly relocate rainwater downpipes and soil stacks. Also think carefully about what kind of insulation you want as some are EPS which might prove to be difficult to sell on in the future. If you’re in a terrace or a semi then the junctions with next door will be ‘odd’.
It’ll also need to be ventilated and drained
Internal wall insulation is good and also provides some extra sound insulation. Will take a reasonable nibble out of your floor areas and you still need to think about window reveals though so decide how that works for you.