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 Post subject: Interesting article on cavity wall fill disadvantages
PostPosted: Fri Jun 25, 2010 11:20 am 
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Lots of Irish people are currently availing of grants to have their cavity walls retrospectively filled.

Here's an article that would make one think twice about it:

http://www.askjeff.co.uk/cavity.html

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 Post subject: Re: Interesting article on cavity wall fill disadvantages
PostPosted: Fri Jun 25, 2010 12:11 pm 
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The cavity is there for a reason, it always puzzled me that retro filling it became acceptable. It's just asking for problems.

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 Post subject: Re: Interesting article on cavity wall fill disadvantages
PostPosted: Fri Jun 25, 2010 12:15 pm 
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I've been told by an experienced civil engineer "You'd be mad NOT to fill them".

Sometimes you'd wonder if anyone in the construction business knows what they're at.

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 Post subject: Re: Interesting article on cavity wall fill disadvantages
PostPosted: Fri Jun 25, 2010 12:28 pm 
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doubleglaze wrote:
I've been told by an experienced civil engineer "You'd be mad NOT to fill them".

Sometimes you'd wonder if anyone in the construction business knows what they're at.

A few did, they were the ould fellas that took too long to do a job, wouldn't adapt the new faster techniques and didn't make a fortune during the boom. Most of them are the lads you see knocking about on small jobs today while the "experts" are on the dole or off to foreign climes.

This is quite an interesting read as it applies common sense and basic fundementals but it will be dismissed as a non expert opinion.

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 Post subject: Re: Interesting article on cavity wall fill disadvantages
PostPosted: Fri Jun 25, 2010 12:32 pm 
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The author, Jeff Howell, claims he is

" my own background experience, as a trained and experienced bricklayer, university construction lecturer, and lately as building columnist for The Sunday Telegraph."

(mentioned in the same above-linked article)

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 Post subject: Re: Interesting article on cavity wall fill disadvantages
PostPosted: Fri Jun 25, 2010 2:29 pm 
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I believe the most efficient retro fit of insulation is to apply externally and face with render. If you're in a semi and considering doing work it might be worth talking to your next door neighbour to achieve economy of scale. Of course it won't work in a victorian redbrick but there are plenty of rendered 60s/70s homes that would fit the bill

I have heard anecdotally that an average 4 bed 80s 'Sorohan' semi costs about €4.5k

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 Post subject: Re: Interesting article on cavity wall fill disadvantages
PostPosted: Fri Jun 25, 2010 3:51 pm 
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It is a very interesting article alright. I work in the construction industry, and I'm starting to come across cases of problems with cavity filled insulation. Dry-lining with insulation on the inside of the walls is a much more preferable solution.


mikewest wrote:
doubleglaze wrote:
I've been told by an experienced civil engineer "You'd be mad NOT to fill them".

Sometimes you'd wonder if anyone in the construction business knows what they're at.

A few did, they were the ould fellas that took too long to do a job, wouldn't adapt the new faster techniques and didn't make a fortune during the boom. Most of them are the lads you see knocking about on small jobs today while the "experts" are on the dole or off to foreign climes.

This is quite an interesting read as it applies common sense and basic fundementals but it will be dismissed as a non expert opinion.


Some big sweeping statements there lads! In my experience (working here and abroad for several years), the Irish construction industry is as competent and capable as any other country.


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 Post subject: Re: Interesting article on cavity wall fill disadvantages
PostPosted: Fri Jun 25, 2010 4:24 pm 
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Quote:
I work in the construction industry, and I'm starting to come across cases of problems with cavity filled insulation. Dry-lining with insulation on the inside of the walls is a much more preferable solution.

Apparently this combination is a good method for heat insulation and damp prevention.

However it's a problem for non-detached houses. Even if you haven't a lazily built party wall, and one which hasn't been compromised by having blocks cut or left out for floor joists, you've might now have as much or more sound leaking in from the non-party walls.

Effectively sound will resonate around the empty cavity when doors are slammed, as doors and windows are sitting in the cavity. Even relatively normal levels of noise can travel from a room via the window through the cavity and in next doors windows. I was explaining this to a builder of semi's (100's of them) and while he agreed it seemed like he'd never considered this before and felt adding cavity insulation afterwards would be a great solution.

Irish (UK really) building regs are particularly poor when it comes to sound. And in reality most people would put up with a cold house than one where the neighbours wake them up on a regular basis, so sound should come first.


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 Post subject: Re: Interesting article on cavity wall fill disadvantages
PostPosted: Fri Jun 25, 2010 4:53 pm 
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sorehead wrote:
Quote:
I work in the construction industry, and I'm starting to come across cases of problems with cavity filled insulation. Dry-lining with insulation on the inside of the walls is a much more preferable solution.

Apparently this combination is a good method for heat insulation and damp prevention.

However it's a problem for non-detached houses. Even if you haven't a lazily built party wall, and one which hasn't been compromised by having blocks cut or left out for floor joists, you've might now have as much or more sound leaking in from the non-party walls.

Effectively sound will resonate around the empty cavity when doors are slammed, as doors and windows are sitting in the cavity. Even relatively normal levels of noise can travel from a room via the window through the cavity and in next doors windows. I was explaining this to a builder of semi's (100's of them) and while he agreed it seemed like he'd never considered this before and felt adding cavity insulation afterwards would be a great solution.

Irish (UK really) building regs are particularly poor when it comes to sound. And in reality most people would put up with a cold house than one where the neighbours wake them up on a regular basis, so sound should come first.




Interesting points Sorehead. However, insulating to prevent heat loss, and sound proofing, are two different procedures / requirements.

For preventing heat loss - you only need to insulate the exposed external walls. There is no need/advantage in insulating party walls.

For sound proofing (b) - you only need to insulate the party wall (with a sound-proof insulation). Propagation of noise within the cavity is unavoidable, unless you fill in the cavity locally at the vertical line of the party wall. This would not be advisable, as it could cause a cold-bridge. The ideal solution is to form a cavity within the party wall, which rarely happens in Ireland (or in any other country).
I agree that the Irish (& UK) building reg.s are very weak on sound proofing.


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 Post subject: Re: Interesting article on cavity wall fill disadvantages
PostPosted: Fri Jun 25, 2010 5:18 pm 
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Why not spray the blocks in the cavity with some kind of sealant before filling with insulation?
Is it possible?

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 Post subject: Re: Interesting article on cavity wall fill disadvantages
PostPosted: Fri Jun 25, 2010 5:45 pm 
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While the ConstructIreland magazine has become a bit of an external insulation trade mag, it does at least try to present the benefits in a fairly thorough way. Over the last 12 months they have had a series of articles by Joseph Little (I think) called 'breaking the mould' where different forms of retrofitted insulation methods were compared. More to do with condensation/dew point than penetrating rain, but very relevant to this discussion none the less.

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 Post subject: Re: Interesting article on cavity wall fill disadvantages
PostPosted: Fri Jun 25, 2010 5:49 pm 
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Longtermrenter wrote:
Why not spray the blocks in the cavity with some kind of sealant before filling with insulation?
Is it possible?

No - it would trap water.

The problem with outsulation is that you've a cavity directly behind it (if you tack it on to existing) - air can circulate in this up to eaves and out - depending. Got to make sure it's sealed. Plus problems of soft surface, fixing around windows (cills etc.) and under soffits and gables.

The problem with insulated plasterboard is that there's a cold bridge at the first floor joists, and there can be condensation behind the board.


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 Post subject: Re: Interesting article on cavity wall fill disadvantages
PostPosted: Fri Jun 25, 2010 6:19 pm 
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The reality is that any form of retro-fitting insulation has their pro's and con's. One system/solution may work well for a particular building, but could be useless for another. Therefore, the most important thing before carrying out any retro-fitting work is to understand the building you are dealing with first, and then pick the method/product to suit around it. Good and impartial advise from an architect or structural engineer, (who has experience in this area), is invaluable and money well spent. It's a mistake to rely on advise from the product supplier, or from Bob the Builder who has "done this on loads of other houses".


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