cavity wall insulation.

[gangman]

Not rat trap more like a flemish garden wall bond. You could see it was an attempt at creating a cavity but without proper cavity ties.

These bungalows were built in the early 30s I think so they should have been able to get ties if they wanted to.

 

[madsey]

I sometimes wonder if any of you guys on here know anything about building at all!

Question: Does filling a cavity wall with insulation compromise the whole point of having a cavity wall,i.e. to stop transfer of damp from outer wall to inner wall??????

Answers given:
Does your house have cavity walls???? DOOO!!!!

Does your house have headers????? DOOO !!!!!

What colour is your front door????? DOOO!!!!!

Is your house built of mud and staw???? DOOO!!!!

Read the question properly before you start to answer the question!!!!!

I have now got the answer for myself.........

having spoken to a professor of building studies and design at birmingham university the answer is as follows........

by completely filling a cavity gap on a building you are risking damp transfer from the outer wall to the inner wall and in turn stopping the flow of air between the walls.
In modern buildings the insulation is pinned to the inner wall thus still leaving a cavity gap between the insulation and outer wall.

Read and learn!

 

[Bahco]

Having spoken to a professor of building studies and design at Birmingham university

Those that can, DO. Those that can't, TEACH!

By completely filling a cavity gap on a building you are risking damp transfer from the outer wall to the inner wall and in turn stopping the flow of air between the walls.

Tell that to the 40 % of houseowners in England that have had Cavity Wall Insulation with no problems!

 

[Balenza]

The professor wrote

by completely filling a cavity gap on a building you are risking damp transfer from the outer wall to the inner wall

Use Bonded bead Cavity Wall Insulation. The beads have a closed cell structure that prevents water absorption or penetration.

These inert beads will not shrink, crack, settle or flow after installation and even if the outer wall is saturated they don't lose their insulation value.

Nor can damp penetrate because the beads are bonded in such a way that air flows between them. This allows moisture to drain away without ever penetrating the inner wall. The special bonding agent ensures that when any future openings of the cavity are made for replacement windows etc, the insulation will stay in place.

Some builders are now constructing 150mm cavities and the wall ties for such widths are becoming more widely available.
A few are also constructing 200mm.

 

[^woody^]

having spoken to a professor of building studies and design at birmingham university the answer is as follows........

by completely filling a cavity gap on a building you are risking damp transfer from the outer wall to the inner wall and in turn stopping the flow of air between the walls.
In modern buildings the insulation is pinned to the inner wall thus still leaving a cavity gap between the insulation and outer wall.

Read and learn!

Give me that professors name and I'll take it up with him - Birmingham University or the University of Birmingham?

He's talking nonsense

By merely building a cavity wall and using ties between the two leafs you are risking moisture transfer. He really needs to qualify the risk, otherwise his statement is meaningless

Insulation is not pinned to the inner wall with a cavity gap "in modern buildings". This is just one of several methods, and certainly not the defacto method

And what if the airflow is reduced, what does this actually mean for the structure?

Did your expert professor also expand on the way brick walls deal with absorption, diffusion and evaporation of rain water over time?

 

[madsey]

The professor did qualify the risks to me,he said to me....
'i wouldn't have cavity wall insulation injected into my house'.

and if it's not good enough for a professor of building studies and design then it's not going in my house!

It's alright saying 'it's alright,you wont get damp coming across the gap'
it's too late when you've got damp patches on your walls,you cant just pump the stuff back out agian!

 

[Balenza]

madsey wrote

The professor did qualify the risks to me,he said to me....
'i wouldn't have cavity wall insulation injected into my house'.

Thats not qualifying the risks.
The fact is your professor doesn't know a lot about cavity wall insulation.

and if it's not good enough for a professor of building studies and design then it's not going in my house!

I expect his home has quite a high heat loss as has yours.
The problem with academics is that they rely on books for their information and many of these books are out dated to the modern methods used in construction nowadays .

It's alright saying 'it's alright,you wont get damp coming across the gap'
it's too late when you've got damp patches on your walls,you cant just pump the stuff back out agian

If you think modern cavity wall insulation will cause damp ingress into your home because of what a professor says then you are very dissillusioned.

 

[Bahco]

I am at present using a hoover to suck out my CWI as the mad professor is not to be ignored!

 

[madsey]

Hey Balenza,
it's obvious by your comments your not in the building trade.

For one thing you dont know this professer his qualifications or experiance.
secondly,on newbuilds they dont completly fill the cavity wall,they
pin the insulation to the inner wall so that there is still a moisture gap.

check out this,you might learn something!http://www.insulation.kingspan.com/uk/pdf/k8.pdf

 

[madsey]

or check this out if you dont have pdf.

http://www.insulateonline.com/index1.htm?products.htm~main

 

[noseall]

woa guys stop arguing.

full fill fibreglass or mineral insulation is acceptable as is partial fill rigid board.

the beauty about the rigid board type is you have the best of both worlds. air is a good insulator so too is expanded plastic. the two together form an effective insulation provided it is installed snug against the inner wall.

i'm not convinced about blown in loose fibre type insulation though. it does encourage air movement within the cavity. air that moves over a surface-cools that surface.

we tend to use dritherm full fill method for its speed and cost. also, i have never been a fan of constructing the inner skin first.

 

[Balenza]

noseall wrote

air that moves over a surface-cools that surface

.

Which is exactly what happens in cavities with rigid board fitted .

Im not a fan of rigid board as I have seen how builders lash the stuff in.
Bonded bead is proven and works well .
I wouldn't pay to much attention to what Kingspan have to say either as their job is to market and sell a product.