Cavity insulation, can it lead to dampness?

[MoonMan2]

An associate of mine is thinking of getting the cavity between the outer brick and inner bricks filled. It is a detached house. I have seen them do it with neighbours. They drill holes into the bricks and squirt some sort of material in.

My question is. Will this material not sit on the ground between the two layers of bricks where there is no DPC?

And if so will this not cause the water to rise up the "material they squirt in" and eventually be abosorbed by the bricks, hence causing dampness, odour and other issues?

 

[dhutch]

I understand in the past it was not unheard of, along with slump of the filling leaving uninsulated areas at the top and below windows. But that with the current fillings, which are normally a closed cell eps ball which are coated with adheasive when blown in these issues are largly resolved.

However Im not expert and would be interested in other replies.


Daniel

 

[jeds]

Cavity insulation can cause an issue if the cavity is unsuitable or the product is not installed correctly. Good installers will survey first to check the cavity and will not install if it isn't right. Choose a good reputable installer and you will be OK.

 

[r896neo]

The insulation itself does not absorb water and so capillary action is not relevant.

 

[WabbitPoo]

capilliary action does not depend on absorption, however....

 

[r896neo]

Ok sorry what should i have said? wicking?

 

[^woody^]

Ok sorry what should i have said? wicking?

Absorption, sorption, diffusion, capillary action, percolation ....

Lots of ways, but if properly done in a suitable wall in a suitable location, then it should be fine

 

[MoonMan2]

if properly done in a suitable wall in a suitable location, then it should be fine

Am a bit confused by the last few posts. I understand what capilliary action is, it's how trees absorb water up through the roots.

Woody, can you give an example or two of where the material would absorb water from the ground and eventually cause dampness?

 

[^woody^]

can you give an example or two of where the material would absorb water from the ground and eventually cause dampness?

Not really, because that scenario is unlikely

You seem to be concerned about the fact that the insulation will bridge the DPC due to it extending down past the DPC towards the ground. The nature of the fibres or beads is such that it will not support moisture travel up it by any method

Also moisture soaking through he outer leaf will run down the face and not across the insulation in the cavity

Current new building practice requires insulation to go down past the DPC in any case

If you have no existing problems with the wall then you should be fine

 

[r896neo]

Forget wabbit's science lesson and take to heart that the insulation will not absorb water and so moisture will not climb its way up through it and bridge your cavity just as woody says.

 

[GuinnessSI]

It depends if there is any agent on the wall. Capillary action could potentially work its way to areas of damp. My senior Hydrostatics lecturer at university used to tell us to think of capillary action as putting two panes of glass together, eventually water from the bottom works its way up regardless of absorption.

Similar principle with brick that doesn’t absorb and cavity insulation, although very rare.

Although I don’t think this is the issue it might be of some relevance.

More likely is that the cavity was damp before and the insulation has aggravated what was there. Also surely you have a warranty with the work and should contact them?

 

[noseall]

I think there could be the 'sensation' that things are more stifled than they were prior to CWI.

Air would have been readily circulating throughout an empty cavity especially one that is vented. This would have an effect on the way a building is heated but no doubt it may have also felt less humid.

Maybe a placebo effect or maybe real, but one or two people have commented on a tangible difference regarding recently filled cavities and dampness.

The desired effect should be a distinct lack of any condensation related issues on the external walls and an improvement on heat retention etc.

But hey ho, the mind works in mysterious ways.

 

[dhutch]

Certainly when I had mine done I got the impression that airtightness of the building had also improved, which could in turn, lead to dampness.

I have some damp, but it is on the sloping skeling of one bedroom, which currently for want of a better explanation I am putting down to condestation, although it doesnt look much like it, on the uninsulated plasterboard which having had the loft done on the same day is be far the coldest surface in the room.


Daniel