Filling Cavity Walls with Pumped Insulation (a ticking time bomb ?)

self3137 · 21-10-2014 12:21pm #1

I have seen plenty of houses built in the 70's and 80's with their wall cavities been pumped full of insulation, this does reduce heat loss from the house, no doubt about that.

However I feel people are ill informed as to possible side effects associated that can cost far more to rectify that any savings in heating bills. Cavities are put in place for a reason and that is to deal with moisture and penetration of rain. It stops it from reaching the inside leaf of the house.

Filling the cavities bridges this cavity allowing moisture to bridge across creating dampness on the inside leaf of the house.Wall ties also get corroded which are put in place to hold the exterior and interior of the house together.

In my opinion if you want to add thermal insulation to your walls do so by adding it to the inside or outside walls, and make sure that you have at least 300mm in the floor of your attic as a starting point.

Would I buy a house that has had its cavities pumped with insulation, not sure I would.

Tefral · 21-10-2014 12:25pm

self3137 wrote: »

Wall ties also get corroded.

What proof would you have of this?

Dtp1979 · 21-10-2014 12:26pm

cronin_j wrote: »

What proof would you have of this?

Aren't wall ties stainless steel or galvanised ??

_Brian · 21-10-2014 12:29pm

self3137 wrote: »

I have seen plenty of houses built in the 70's and 80's with their wall cavities been pumped full of insulation, this does reduce heat loss from the house, no doubt about that.

However I feel people are ill informed as to possible side effects associated that can cost far more to rectify that any savings in heating bills. Cavities are put in place for a reason and that is to deal with moisture and penetration of rain. It stops it from reaching the inside leaf of the house.

Filling the cavities bridges this cavity allowing moisture to bridge across creating dampness on the inside leaf of the house.Wall ties also get corroded which are put in place to hold the exterior and interior of the house together.

In my opinion if you want to add thermal insulation to your walls do so by adding it to the inside or outside walls, and make sure that you have at least 300mm in the floor of your attic as a starting point.

Would I buy a house that has had its cavities pumped with insulation, not sure I would.

But.
The product is designed not to draw moisture across the width of the cavity and as per it's liscence it shouldn't be used in areas prone to driving rain.

Like many products, if used correctly it works as described.

I'd say a bigger issue with cavities is poor building detailing where you see mortar splashed all over wall ties, this draws moisture straight onto the inner leaf.

Andrew_Doran · 21-10-2014 1:51pm

All the reports of problems I have read of damp on the 'net have been from England where rockwool/fibre fill is popular. It tends to be poly beads used here and they don't wick moisture.

tred · 23-10-2014 1:27pm

Andrew_Doran wrote: »

All the reports of problems I have read of damp on the 'net have been from England where rockwool/fibre fill is popular. It tends to be poly beads used here and they don't wick moisture.

Read the specs of how the beads are installed, how the bond, and how they still breathable. Haven't seen or heard of a moisture ingress problem yet because of bead. its usually another root cause. Id be more concerned about the ventilation in these houses after bead and window upgrades. a lot don't even standard room vents.

Filling Cavity Walls with Pumped Insulation (a ticking time bomb ?)

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