Jump to content
House Price Crash Forum
Saving For a Space Ship

Could The Cavity-Wall Insulation Scandal Rival Ppi? - Dt Article

Recommended Posts

Could the cavity-wall insulation scandal rival PPI?

http://www.telegraph.co.uk/finance/property/advice/11411880/Could-the-cavity-wall-insulation-scandal-rival-PPI.html

Article is a bit vague on stating what type of insulation has a damp problem.

I assume its the blown paper & fibreglass type, not the rigid foam.

Edited by Saving For a Space Ship

Share this post


Link to post
Share on other sites
Guest

I'd heard rumours of CWI being a bad idea, but it is so all pervading that one could be forgiven for presuming it is a sound principle.

Share this post


Link to post
Share on other sites

I'd heard rumours of CWI being a bad idea, but it is so all pervading that one could be forgiven for presuming it is a sound principle.

It is sound, as long as the moist air is removed from house and replaced with dry. I'm not sure I buy the moisture from the outside penetrating the inside walls via insulation, but the better the house insulated (and the more people live in it), the more moist the air inside gets.

Take a normal 2 up 2 down, add PVC windows, cavity wall and loft insulation, cover the vents (which, if not covered, totally defeat the purpose of the above) and the house does get warmer, but also very very wet. It's just a matter of time then until the mold settles and timbers start to rot (unless the felt paper promptly destroyed itself to save them). Properly chosen (see building regs) and installed MVHR with a heat exchanger sorts it out in a week. Then there's a science to properly run MVHR and lack of programmable controllers that do the job, but that's a different story.

Share this post


Link to post
Share on other sites

Properly chosen (see building regs) and installed MVHR with a heat exchanger sorts it out in a week. Then there's a science to properly run MVHR and lack of programmable controllers that do the job, but that's a different story.

I have stripped my place down to just the structure with the prime reason to fit one of these - figuring out the ducting layout/positioning is key. Not easy but it makes the air quality much better.

Share this post


Link to post
Share on other sites

Are they trying to imply that these badly built Victorian wrecks have cavity walls?

Of course they will have damp and other associated problems, those buildings are well past their sell by date and are worthless. The value of the land they sit on is another thing.

4085238_PICTURE-BY_3195383b.jpg

Share this post


Link to post
Share on other sites

I was going to apply for the grant available to have CVI installed a while ago but read an article by the same guy in the Telegraph a while back.

http://www.askjeff.co.uk/cavity-wall-fill/

it completely changed my mind and I would go so far as to say that I wouldn't buy another house with it installed until more is known about the long term affects. Too risky in my view and my house isn't particularly cold anyway.

I live in a mid terrace and the BTL guy who owns next door is an Architect, and he won't have it installed either. The other side of me also lets his property (currently working in USA) decided against it too when I showed him the article.

Edit to add: I've learnt so much from this guy's column in the Telegraph and he's well worth listening to imo.

Edited by Solitaire

Share this post


Link to post
Share on other sites

I have the fibre type insulation, live in Zone 4 and have an exposed West facing wall.

I have not had any problems since installed 4 years ago.

I think that the reason is that the outside wall was spar rendered years ago. When this became worn, I painted the outside with an exterior paint. Now, the outside wall does not get wet because of the paint.

The house is noticeably warmer.

Share this post


Link to post
Share on other sites

Its hard to find someone in the UK building industry who has an honest, truthful opinion on houses

At best, the trades tend to have a narrow focus. Very few have an understanding of a house as a whole.

All I tend to get is 'A mate told me ....' stuff. Some trades are outright idiots/conmen.

Don;t get me started of labourers pretending to have a trade. Or any technique.

At worse, you have a load of scamsters hanging around on the edge with heavily sold crap - upvc windows, cavity wall filling.

The Telegraph is interesting as he's bright and thoughtful. And not a builder - he started off doing a degree in Nuclear Physics before going to full-time bricklaying and FE teaching. His book are well-worth reading.

Share this post


Link to post
Share on other sites

I have an Edwardian property (built 1930's) within 500 metres of a sandy beach Westward facing.

Wintertime a lot of sand gets blown off the beach and lays about in the streets. So much so the council don't bother clearing it up till Spring.

The cavity wall to the front has filled with sand over the years when it has blown through the airbricks or got in otherwise at the eaves. Slow process but eventually it all builds up. Couple of years ago noticed a damp problem in my dining room. Called my builder round who suspected it was this sand allowing water to breach the gap.

Solution is not easy or inexpensive. In the end we took the plaster off back to the brickwork and dry lined the wall plaster boarded, then new plaster. This turned out to be the cheapest option and will be good for all the time the treated battens stay viable. Soon as they rot the wall will have problems but builder chap reckons that is 30+ years down the road.

Other than this is was a case of plaster off remove some of the bottom course of bricks and try to tease out the sand. No guarantee you would get it all and it would only fill up again in time anyway.

Share this post


Link to post
Share on other sites
Guest eight

It is sound, as long as the moist air is removed from house and replaced with dry. I'm not sure I buy the moisture from the outside penetrating the inside walls via insulation, but the better the house insulated (and the more people live in it), the more moist the air inside gets.

Take a normal 2 up 2 down, add PVC windows, cavity wall and loft insulation, cover the vents (which, if not covered, totally defeat the purpose of the above) and the house does get warmer, but also very very wet. It's just a matter of time then until the mold settles and timbers start to rot (unless the felt paper promptly destroyed itself to save them). Properly chosen (see building regs) and installed MVHR with a heat exchanger sorts it out in a week. Then there's a science to properly run MVHR and lack of programmable controllers that do the job, but that's a different story.

So basically any attempt to insulate a typical UK house results in dampness?

Share this post


Link to post
Share on other sites

So basically any attempt to insulate a typical UK house results in dampness?

No. Any badly thoughtout attempt will probably result in damp.

Share this post


Link to post
Share on other sites

I'm reading through this Hansard Report - it will take some time but thus far I'm not reassured about CWI.

Westminster Hall Tuesday 3 February 2015

[Mr Adrian Sanders in the Chair]

Backbench business

Cavity Wall Insulation

http://www.publications.parliament.uk/pa/cm201415/cmhansrd/cm150203/halltext/150203h0001.htm

Edited by Solitaire

Share this post


Link to post
Share on other sites

So basically any attempt to insulate a typical UK house results in dampness?

Yes, you are correct.

The typical UK housing stock is 120 years old a fit for demolition. They were 'designed' to have open fires, no insulation, outside toilette, you kept warm by wearing more clothes and gettign your 7 kids to shovel more coal on the fire.

IMO most pre 60's need demolishing, or making the owners pay even more tax to make up for their energy inefficient houses. Like car tax for housing.

Share this post


Link to post
Share on other sites

Well, having read the Hansard Report I certainly won't be getting CWI. I'm sure the majority of installations are fine but there are enough contra-indications that I wouldn't be confident in getting it done.

It seems that CWI should not be installed in Category 4 and some Category 3 properties re driving rain. Unless I'm reading the map wrong it seems to include NI, Cornwall, Wales, half of Scotland and pretty much the whole of the West coast of UK. (see map on page 39) http://www.planningportal.gov.uk/uploads/br/BR_PDFs_ADC_2004.pdf

One person found it had nullified their insurance, presumably because they didn't notify the insurance company that they were having the work done but my overriding concern is that the installers and CIGA seem to be actively obstructive in remedying any fault with the initial survey that is done and installation problems. So if you do get damp and mould problems after installation you'll have a real battle to get things put right.

As the energy saving is said to be only around £100 per year I'll give it a miss.

Share this post


Link to post
Share on other sites

In fact we were in this situation, sort of. No cavity insulation because of solid walls. However, we did fit uPVC windows and put in suspended ceilings with lots of insulation. Result, place reasonably snug but as we had got rid of the draufgrs along the way we had lots of condensation leading to mold. I new abou heat recover ventilatio but was not about to tear the place apart to fit it.

Then I triped over single room heat recovery ventilators. They really consist of nothing more than a couple of fans and a heat exchanger. They suck air in form outside through the heat exchanger and blow out the warm, moisture laden, air through the heat exchanger. So the incoming air is warmed up. Result is lower humidity in the room without too much heat loss.

In our case it has worked as well as we hoped. No more condensation, bedroom warmer as we don't have a window open a crack all the time and no noise from outside. Downside is that the thing does make a bit of noise itself but I reckon the trade off is fine. The one we got was a Vent Axia but lost of different makes available. Fitting was a matter of putting a 4" hole in the wall and lining it with a bit of 4" plastic pipe. I paid about £150 or so for the one we bought, they were on sale that day normaly about £170 for that model. You can pay a lot more and I don't see what more they can do.

All in all, one of my better decisions.

If I were building a place from scratch the rules would be insulation and more insulation together with heat recover ventilation.

Share this post


Link to post
Share on other sites

The main problem with fiber/paper/PU foam insulation that has been installed after the house is built is the fact you will always end up with bridging from the outer wall to the inner wall, if the outer wall is not waterproof this bridge transfers the water along it from outer to inner wall this what results in damp the worst product has got to be paper based insulation as it all falls to the bottom of the cavity

Just about all face bricks are porous and the same goes for concrete blocks hence why concrete blocks are rendered but face bricks are generally left/used for their aesthetic appeal and are no where near as porous as concrete blocks and will not cause damp unless they have a bridge,this is reason when insulating this type of wall from the building stage the insulation used is predominantly kingspan PU foam/XPS foil backed boards or similar and it common practice to have the boards attached to the inner wall with specifically designed fasteners

I know of one local council that has spent 10`s-of thousands of pounds rectfeiing damp problems caused by PU foam insulation bridging problems in their own properties so yes this could be the next PPI

Share this post


Link to post
Share on other sites

I suspect that in quite a lot (but certainly not all cases) the problem with CWI is everything else that has probably been done to the house. uPVC windows and doors which are pretty airtight (unless there are trickle vents), fireplaces get blocked-up, some people even put draught excluder's on the loft hatch and some even block up the eaves in the attic, leaving nowhere for the condensation that builds-up in the house to escape.

The average person sweats and breathes out around 750ml of water a day, then there is the steam generated through cooking and bathing, and if you've house plants they transpire. That's several litres of water a day which needs to escape from somewhere, if it doesn't it'll eventually cause mould, which is why modern well insulated homes have things like automatic extractor fans in kitchens and bathrooms.

Share this post


Link to post
Share on other sites

I understand paper based insulation will carry moisture through the wall but foam is waterproof and moisture will not pass through it. Bridging is a thermal transfer issue and not moisture transfer problem. Modern houses use the foil backing with special fasteners to create a very small air gap to prevent thermal bridging. Where thermal bridging occurs you will get condensation at the point of bridging.

Share this post


Link to post
Share on other sites

I understand paper based insulation will carry moisture through the wall but foam is waterproof and moisture will not pass through it. Bridging is a thermal transfer issue and not moisture transfer problem. Modern houses use the foil backing with special fasteners to create a very small air gap to prevent thermal bridging. Where thermal bridging occurs you will get condensation at the point of bridging.

The problem with foam injected into the cavity is the fact you can't tell if the cavity is full this inevitably leaves pockets of air with a physical bridge from the outer skin to inner skin this dose cary moisture (if any moisture gets through the outer skin),theres a whole council estate near me thats having this problem after having PU foam CWI, they have damp patches all over the houses in a random fashion from floor level down stairs to ceiling level upstairs none of the house`s ever had damp problems before PU /CWI

They are now having to render the houses which are face brick outer skin

Share this post


Link to post
Share on other sites

The problem with foam injected into the cavity is the fact you can't tell if the cavity is full this inevitably leaves pockets of air with a physical bridge from the outer skin to inner skin this dose cary moisture (if any moisture gets through the outer skin),theres a whole council estate near me thats having this problem after having PU foam CWI, they have damp patches all over the houses in a random fashion from floor level down stairs to ceiling level upstairs none of the house`s ever had damp problems before PU /CWI

They are now having to render the houses which are face brick outer skin

The air pockets cause different temperatures on the inner surface of the wall - the damp patches are condensation forming on the coldest points. A good test of this is if you reduce a section of lagging in the loft - condensation will form where this has been exposed. Increasing the thermal efficiency of a house magnifies any weaknesses in the insulation. With timber structures this can cause serious problems if the condensation occurs within the structure - interstitial condensation - strangely called leaky building syndrome in New Zealand where it has nothing to do with water ingress. I agree with you whole heartedly that unless done properly I.e. when the house is built then it is a disaster in the waiting for some properties.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

  • The Prime Minister stated that there were three Brexit options available to the UK:   219 members have voted

    1. 1. Which of the Prime Minister's options would you choose?


      • Leave with the negotiated deal
      • Remain
      • Leave with no deal

    Please sign in or register to vote in this poll. View topic


×

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.