Pumped in insulation
Discussion
If the property has a brick face and is even moderately exposed to wind driven rain I wouldn't do it.
Filling existing masonry cavities can be fraught with problems unless, amongst a number of things, a) the cavities are pristine b) there is no significant exposure to wind driven rain. A full examination of the cavities and proper risk evaluation should be carried out before evn thinking about this. The installers by and large are not interested and only want to sell the system.
I've lost count of the number of properties i've looked at which have received this treatment and suffered major damp issues not much further down the line.
Filling existing masonry cavities can be fraught with problems unless, amongst a number of things, a) the cavities are pristine b) there is no significant exposure to wind driven rain. A full examination of the cavities and proper risk evaluation should be carried out before evn thinking about this. The installers by and large are not interested and only want to sell the system.
I've lost count of the number of properties i've looked at which have received this treatment and suffered major damp issues not much further down the line.
Lotobear said:
If the property has a brick face and is even moderately exposed to wind driven rain I wouldn't do it.
Filling existing masonry cavities can be fraught with problems unless, amongst a number of things, a) the cavities are pristine b) there is no significant exposure to wind driven rain. A full examination of the cavities and proper risk evaluation should be carried out before evn thinking about this. The installers by and large are not interested and only want to sell the system.
I've lost count of the number of properties i've looked at which have received this treatment and suffered major damp issues not much further down the line.
Isn't this actually a major issue at the moment? It was on our local news not so long ago about those that were done under the incentivised scheme. I took interest as we had our last place done.Filling existing masonry cavities can be fraught with problems unless, amongst a number of things, a) the cavities are pristine b) there is no significant exposure to wind driven rain. A full examination of the cavities and proper risk evaluation should be carried out before evn thinking about this. The installers by and large are not interested and only want to sell the system.
I've lost count of the number of properties i've looked at which have received this treatment and suffered major damp issues not much further down the line.
Having done some reading since we moved I'd completely changed my views on it, and they seemed to be reinforced by the local news article. They were speaking to one company who were doing removal of the insulation on properties, and they said they could compelte jobs fast enough, they had that long a list of properties to do.
Looking like a booming business venture!
Swervin_Mervin said:
Looking like a booming business venture!
Is this the modern version of Keynes' "pay a man to dig a hole" theory? I do wonder if the retrofitting of inappropriate insulation is going to become a big scandal in the long run, up there with PPI, leaky condo crises, etc. Not only is it unpleasant and unhealthy for those living with damp issues that it may cause, but in some cases can cause structural issues with the house such as rotting timbers.
...think about the reason why the cavity is there!
This is not new, it's been going on for 20 years that I can recall. What has happened is it's become more popular in response to enegry policy and the usual response from fly by night companies sensing a fast buck
I have personally specced and supervised a contract to remove cavity insulation from unsuitable properties and acted on many occassions as an expert witness in litigation surrounding its inappropriate use.
Even the BBA will say that mineral fibre cavity insulation (one of many forms) will not hold water but I can personally recall wringing streams of water out of handfuls of the stuff as it was pulled out of an unsuitable cavity.
Think of cavity trays, dpc's and other critical features - how can they possible function properly once bridges by blown in cavity insulation. Dirty wall ties are the other issue.
Would not go near it personally, though of course many will have fitted it without issue. I just think the risk are too great.
This is not new, it's been going on for 20 years that I can recall. What has happened is it's become more popular in response to enegry policy and the usual response from fly by night companies sensing a fast buck
I have personally specced and supervised a contract to remove cavity insulation from unsuitable properties and acted on many occassions as an expert witness in litigation surrounding its inappropriate use.
Even the BBA will say that mineral fibre cavity insulation (one of many forms) will not hold water but I can personally recall wringing streams of water out of handfuls of the stuff as it was pulled out of an unsuitable cavity.
Think of cavity trays, dpc's and other critical features - how can they possible function properly once bridges by blown in cavity insulation. Dirty wall ties are the other issue.
Would not go near it personally, though of course many will have fitted it without issue. I just think the risk are too great.
Polybead insulation is a quite different proposition from blown fibre, of course.
I certainly wouldn't touch the latter with a bargepole, but I've built literally thousands of properties with polybead, without any damp bridging issues that I'm aware of. Polybead isn't perfect, of course - you can get localised pockets that reduce the efficiency, slightly - but still a hell of lot better than blown fibre.
Sorry - still can't advise you on any installers around Manchester, though!
I certainly wouldn't touch the latter with a bargepole, but I've built literally thousands of properties with polybead, without any damp bridging issues that I'm aware of. Polybead isn't perfect, of course - you can get localised pockets that reduce the efficiency, slightly - but still a hell of lot better than blown fibre.
Sorry - still can't advise you on any installers around Manchester, though!
Equus said:
Polybead insulation is a quite different proposition from blown fibre, of course.
I certainly wouldn't touch the latter with a bargepole, but I've built literally thousands of properties with polybead, without any damp bridging issues that I'm aware of. Polybead isn't perfect, of course - you can get localised pockets that reduce the efficiency, slightly - but still a hell of lot better than blown fibre.
Sorry - still can't advise you on any installers around Manchester, though!
Thank you I certainly wouldn't touch the latter with a bargepole, but I've built literally thousands of properties with polybead, without any damp bridging issues that I'm aware of. Polybead isn't perfect, of course - you can get localised pockets that reduce the efficiency, slightly - but still a hell of lot better than blown fibre.
Sorry - still can't advise you on any installers around Manchester, though!
You are still deliberately blocking a cavity the design intent of which is to provide a break between the external and internal surfaces of the building envelope to prevent the passage of damp from the exterior to the interior
Personally I would never do it, not least in the West if the UK.
Just be aware of the risks as removing bonded bead insulation from a cavity once installed is not going to be a simple task.
Personally I would never do it, not least in the West if the UK.
Just be aware of the risks as removing bonded bead insulation from a cavity once installed is not going to be a simple task.
Lotobear said:
You are still deliberately blocking a cavity the design intent of which is to provide a break between the external and internal surfaces of the building envelope to prevent the passage of damp from the exterior to the interior
... but if you do it with polybead insulation, you're blocking it with a material that is virtually incapable of transmitting moisture from one side to the other,Many hundreds of thousands of modern homes have fully filled cavities, by intentional design.
Fibre insulation in a fully filled cavity is questionable, particualrly in areas of high exposure, and there have been numerous instances of defects - moisture can 'track' along the fibres from one side to another, and water can cling to the fibres and saturate the material.
The risk of moisture tracking across hundreds of tiny, spherical objects that are each impervious to water is infinitesimally small.
Here's a practical test for you:
1) Fill your bath with water.
2) Place a section of fibreglass insulation batt into the bath.
3) Watch it sink as the water soaks into it.
Now:
1) Fill your bath with water.
2) Place a section of polystyrene foam into the bath
3) Wait until the water soaks through it until its upper surface becomes damp.
4) Continue to wait...
5) Continue to wait.....
6) Continue to wait.....
7) Continue to wait.....
Equs,
I realise you are the resident polemisist on here but, even taking that into account, your simple 'test' is quite clearly not remotely comparable to how a cavity wall works and ignores factors such as wind pressure, inherrent workmanship defects such as snotty wall ties, bridging mortar snots (which cannot dry out when encapsulated by polystyrene) and the near impossibility of attempting to achieve full and consistent coverage when injecting beads through small holes into a cavity wall. The added problem of 'holes' resulting in thermal bridges leading to condensation spots on internal walls whilst unrelated to the issue of tracking dampness is just another risk which, on balance, would make me run a mile from this or any of these retrospective cavity fill products.
Personal view of course, but based upon seeing the detimental effects first hand in many cases in the NW of the UK
I realise you are the resident polemisist on here but, even taking that into account, your simple 'test' is quite clearly not remotely comparable to how a cavity wall works and ignores factors such as wind pressure, inherrent workmanship defects such as snotty wall ties, bridging mortar snots (which cannot dry out when encapsulated by polystyrene) and the near impossibility of attempting to achieve full and consistent coverage when injecting beads through small holes into a cavity wall. The added problem of 'holes' resulting in thermal bridges leading to condensation spots on internal walls whilst unrelated to the issue of tracking dampness is just another risk which, on balance, would make me run a mile from this or any of these retrospective cavity fill products.
Personal view of course, but based upon seeing the detimental effects first hand in many cases in the NW of the UK
Lotobear said:
...your simple 'test' is quite clearly not remotely comparable to how a cavity wall works and ignores factors such as wind pressure, inherrent workmanship defects such as snotty wall ties, bridging mortar snots (which cannot dry out when encapsulated by polystyrene) and the near impossibility of attempting to achieve full and consistent coverage when injecting beads through small holes into a cavity wall.
And your assertions disregard the fact that moisture flows in two directions; hence even solid brick walls with no cavities work in the majority of instances, when kept heated, as the heating in the house drives the moisture back out faster than it can soak in from the actually very limited exposure to driven rain that it gets in operation. I actually live in a solid brick-walled house, over 130 years old, in an exposed coastal position, with no damp penetration. With full fill cavity insulation, the inner leaf is within the insulated envelope, so any damp penetration along mortar snots etc. is fighting the thermal mass of the masonry.
Yes, gross masonry defects can cause damp penetration, pretty much regardless of method of cavity insulation (or none). But don't confuse cause and effect.
Yes, I have acknowledged that polybead can suffer from voids unless properly installed: but it's still dramatically better than having an insulated cavity that is basically one big void.
Is your advice to leave the cavity uninsulated, then?
I'd be genuinely interested in evidence of instances where insulation defects (not gross masonry defects) have caused damp penetration with polybead (not blown fibre) cavity fill insulation, as in 35 years in the industry, including as head of design and technical for a major housebuilder that used polybead (and where I was first port of call for customer technical complaints of this sort), I've yet to encounter one.
Swervin_Mervin said:
Interesting stuff Equus.
What's the view wrt use of panels vs beads? Do they generally have many issues?
Panels of rigid foam insulation?What's the view wrt use of panels vs beads? Do they generally have many issues?
They're ok; the usual problem is that it's difficult to get them to butt up against each other (or against the thermal cavity closers at openings) accurately, so you get 'leakage' (thermal bridging) at the board edges. If you take a picture with a thermal imaging camera, it's often possible to discern a thin grid of 'hot' lines that follow the edges of the individual boards.
But manufacturers are now coming out with boards with T&G edges that slot into each other more accurately, minimising or overcoming this problem.
As much as it may appal Lotobear, full fill cavity insulation will become universal on new-builds... insulation standards are now so high that the alternative - to increase the cavity width sufficiently to allow both insulation and clear cavity - is becoming unpalatable for structural reasons.
Irrelevant in terms of this thread, of course, as you can't retrofit boards into an existing cavity wall.
Yes, I'm of course familiar with the raincoat/overcoat analogy and understand very well the other principles you outline from way back in the college days. In Cumbria and the North West we suffer from a high driving rain index (check the BRE doc) and I can tell you from experience of surveying many thousands of properties, and diagnosing building failures, over more years than I care to remember that no solid brick wall will resist the driving rain we experience here. Perhaps you live on the East coast though?
I'm a great believer in experiential wisdom - like you I have been working in property and construction for 35 years now, initially in design and also for a major Construction PLC. These days I'm a chartered surveyor running my own practice, and based upon first hand experience of a diverse range of properties and types, would never recommend retro fitting any form of cavity insulation in the West of the UK as the risks are simply too great (IMO) - my firms PI premiums are the lowest they have ever been so I will continue to take my own advice!
anecdotal stuff of course but worth reading, at least for the OP:
http://www.premier-heritage.co.uk/2009/08/cavity-w...
I'm a great believer in experiential wisdom - like you I have been working in property and construction for 35 years now, initially in design and also for a major Construction PLC. These days I'm a chartered surveyor running my own practice, and based upon first hand experience of a diverse range of properties and types, would never recommend retro fitting any form of cavity insulation in the West of the UK as the risks are simply too great (IMO) - my firms PI premiums are the lowest they have ever been so I will continue to take my own advice!
anecdotal stuff of course but worth reading, at least for the OP:
http://www.premier-heritage.co.uk/2009/08/cavity-w...
Lotobear said:
... I can tell you from experience of surveying many thousands of properties, and diagnosing building failures, over more years than I care to remember that no solid brick wall will resist the driving rain we experience here. Perhaps you live on the East coast though?
I now live on the east coast in Norfolk, yes. But when I say on the east coast, I mean on the coast... I look out of my front windows onto flat salt marsh, with the sea in clear view about half a mile beyond.Before moving here I lived on the south west coast (in a solid-walled house, again).
I spent a fair amount of my youth in Cumbria, though - my grandparents were hoteliers up there - and I have also lived and worked in the North West (I was manager of an architectural practice in Lancashire, on the edge of the West Pennine Moors for a while), so I'm familiar with your climate.
I would suggest that your opinion is being heavily coloured by your occupation, though. In the same way that owners of a particular car will only complain about its unreliability on internet forums, never its reliability, if all you ever get to see are the failures, you'll get a very skewed perspective.
I ask again: is your advice to leave the wall uninsulated?
I do not deny that gross masonry defects can cause problems, whatever the cavity insulation - and it's notable that the link you have just provided shows dreadful mortar issues which are quite clearly the primary cause - but to suggest that no-one should insulate their cavities with suitable insulation, properly installed, is bordering on reckless, in my opinion.
Yes, as a personal view I would always leave the cavity clear in an existing property as you can never be sure of it's actual condition regardless of endoscope inspections, periodic opening up and the like.
Most if not all social housing revites, and many others, in this County are now being carried out with externally applied insulation and render (I am guessing due to previous issues with cavity fill). I have to confess that I have no direct experience of this system as a specified but there are obvious practical issues of dealing with eaves detailing, rainwater goods, reveals and the like but it finds obvious favour as the tenants do not need to be decanted.
Personally I am in favour of internally applied insulation which is what I have done in many parts of my own house using Gyproc MF system (solid built, over 150 years old). This has been succesful though it's not practical in all cases and there are interstitial condensation risks to evaluate. What I like about it is the dynamic lag is short as you are not heating up a large thermal mass, at least not initially.
Before this, many of our external walls were damp due to penetrating moisture, despite being externally roughcast.
Yes, my views are most definately coloured by my occupation!
Most if not all social housing revites, and many others, in this County are now being carried out with externally applied insulation and render (I am guessing due to previous issues with cavity fill). I have to confess that I have no direct experience of this system as a specified but there are obvious practical issues of dealing with eaves detailing, rainwater goods, reveals and the like but it finds obvious favour as the tenants do not need to be decanted.
Personally I am in favour of internally applied insulation which is what I have done in many parts of my own house using Gyproc MF system (solid built, over 150 years old). This has been succesful though it's not practical in all cases and there are interstitial condensation risks to evaluate. What I like about it is the dynamic lag is short as you are not heating up a large thermal mass, at least not initially.
Before this, many of our external walls were damp due to penetrating moisture, despite being externally roughcast.
Yes, my views are most definately coloured by my occupation!
External insulation is, of course, a perfectly good idea where it is appropriate in Planning and architectural terms, but it frequently isn't desirable or practical.
HA's usually have the advantage of owning the whole of a block of housing stock, too. Since it's Manchester we're talking about...
And do you know, that's the first time I've noticed that the Coronation Street set appears to be built with cavity walls (stretcher bond), whereas to be authentic it should be 9" solid brick in common with the tens of thousands of other Manchester terraces that don't all suffer from damp penetration, despite being in the North West.
Of course, I'm sure you'll appreciate that most people's only experience of Chartered Building Surveyors is with structural surveys when buying their house... your preoccupation witharse-covering minimising your PI risks will seem dreadfully familiar to them, I suspect... but meanwhile in the real world some of us are forced to take a much more pragmatic view when balancing potential risks vs. potential benefits.
HA's usually have the advantage of owning the whole of a block of housing stock, too. Since it's Manchester we're talking about...
And do you know, that's the first time I've noticed that the Coronation Street set appears to be built with cavity walls (stretcher bond), whereas to be authentic it should be 9" solid brick in common with the tens of thousands of other Manchester terraces that don't all suffer from damp penetration, despite being in the North West.
Of course, I'm sure you'll appreciate that most people's only experience of Chartered Building Surveyors is with structural surveys when buying their house... your preoccupation with
Dreadful facade, tut tut - the lower orders eh, no taste?
It's not about arse covering, it's just providing informed advice to the client based upon seeing so many such installations go wrong and not wishing to see them put in the same position.
What would be reckless is to recommend cavity fill where local experience tells you that it would be inappropriate and carry an unacceptably high risk
Stopped doing structural surveys ago, most of my work is commercial and project based
It's not about arse covering, it's just providing informed advice to the client based upon seeing so many such installations go wrong and not wishing to see them put in the same position.
What would be reckless is to recommend cavity fill where local experience tells you that it would be inappropriate and carry an unacceptably high risk
Stopped doing structural surveys ago, most of my work is commercial and project based
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