Wool Insulation which has degraded over time

[ltownranger]

Hi,

Just wondering if anybody has dealt with degraded wool insulation in their home? We have a 30 year old house which appears to have been insulated with rockwool insulation on Day 1. From what I can see, some of the wool has dropped down in the cavity walls over time meaning parts of the house don't have proper insulation. It is 32 years since the house was built so I suppose some kind of decrease in quality was to be expected.

My understanding is that I can't pump the walls with beads due to the wool. Drywalling is one option we are considering but I am not convinced that solves the problem. I know external insulation is an option but that is a very expensive solution.

Just wondering if anyone has dealt with this issue in the past and would be able to provide some advice?

Thanks.

 

[Micks'r]

"From what I can see, some of the wool has dropped down in the cavity walls over time meaning parts of the house don't have proper insulation."

How are you seeing this?

 

[ltownranger]

"From what I can see, some of the wool has dropped down in the cavity walls over time meaning parts of the house don't have proper insulation."

How are you seeing this?

Nothing too scientific - looked down through the cavity wall in gap in attic with a torch.

I should also add that we have had mould form in the top corners of a couple of the upstairs bedrooms so I thought this was linked to poor insulation. I'm no expert on this however.

 

[Micks'r]

For the cavity, the only option that I'm aware of is to have what is in the cavity removed and then redone with new insulation (e.g. certified bonded bead).
You will need the cavity filled in any case if you go with external insulation.
Imo, internal insulation should be the last resort.

Bear in mind that some cavity walls are constructed where the inner leaf wall is a block course higher than the outer leaf wall resulting in that top block of the inner leaf being uninsulated. If this is the case then the insulation hasn't dropped per se but a thermal bridge exists at the top of your walls. If this is the case then insulation can be added to link the cavity insulation with the attic insulation (how to do this depends on a number of things)

On the damp / mould issue, you are correct that the cooler wall surface higher on the wall is where enough condensation is occurring regularly to allow mould to exist. Improving your ventilation efficiency will help enormously with this so this should be considered too.

 

[ltownranger]

Thanks for the feedback. It may very well be a ventilation issue. I might get an energy assessor to look at the house and give us some recommendations on how to resolve the issue.

 

[bankrupt]

Imo, internal insulation should be the last resort.

I am curious about this point, is it because internal insulation will be less effective somehow? I'd guess that it's not easier to retrofit external insulation.

 

[Micks'r]

I am curious about this point, is it because internal insulation will be less effective somehow? I'd guess that it's not easier to retrofit external insulation.

Imo, there are many reasons why iwi is a poor specification, here are some in no particular order:
- loss of thermal mass
- introducing significant thermal bridging
- difficult to achieve decent air tightness
- moving the dew point from within the wall to within the room
- real risk of interstitial condensation, damp & mould
- reduction in internal floor space
- significant internal disruption (when retrofitting)
- can be more challenging to fix heavy objects to