Cavity Wall Insulation
(What are the benefits? …..…..DAMP)
From October 2008 all domestic buildings (being built, rented or sold) were required ‘by Law’ to have an Energy Performance Certificate (EPC) to help improve the energy efficiency of the building. The EPC provides an ‘A’ to ‘G’ rating for the building, ‘A’ being the most efficient and ‘G’ the least and to-date a ‘D’ rating is currently being banded as the average.
It is claimed that around a third of heat loss in a house is through its roof and walls and currently there is a government drive (supported by television advertising and the offer of Home Improvement Insulation Grants) to encourage home owners to increase loft insulation and also to fit cavity wall insulation, as it is claimed this can save on average around £180 per annum on heating costs!
However were you aware that by installing cavity wall insulation, whilst you may well be saving some money on fuel costs, you could also be creating a major expense for the future……..damp!
Example of cavity wall insulation
The cavity wall (as we know it) dates back to the early 1900’s and is commonly found in the coastal areas around Britain, used to reduce the risk of rain penetration. In the 1920’s, local building by-laws encouraged the construction of the cavity wall and by the 1940’s it had become the Industry Standard. The familiar cavity wall (as we know it) is two leaves of brickwork, forming a 60mm cavity and tied together with metal wall ties.
Even back in the good old 1970’s concerns were being expressed over Energy Conservation and home owners were then being encouraged to introduce loft insulation and it wasn’t long after that cavity wall insulation was also being recommended.
Fill your cavities with foam, polystyrene, mineral wool or any other material you can introduce through a small hole in the wall and you will save energy and loads of money. Sounds good, but what if by introducing this insulation you increased the risk of damp to your property, which in turn would cause internal decorative spoiling, plaster damage, fungal decay to structural and joinery timbers and also accelerate the risk of corrosion to the metal wall ties.
Could that really happen? Well the answer is yes and it is.
Paul Carter, the principal of Premier Heritage, has investigated hundreds of buildings over the past 20 years of so, where damp has affected internal decorations etc and found that the damp present was due to bridging of the cavity by the earlier installed insulation materials. Whilst some of these cases were wrongly diagnosed by others as rising damp, most of these buildings (if not all) retained a physical damp proof course, the newest being a 1980’s brick built bungalow in Hampshire.
Ok, lets put this into perspective, there have been thousands of cavity built houses within the UK that have been insulated and a good majority of these don’t currently have nor will ever have a problem with damp. But there are a great number that have and no doubt more will be affected in the years to come!
Increased rainfall in past years has resulted in a noticeable increase in damp problems affecting conventional cavity-constructed housing, due to moisture penetrating / bridging the cavities and in particular on the weather prevailing elevations and this isn’t a problem relating to current rainfall, but a gradual build of damp over many years.
Rainwater driving into the masonry of a building can penetrate the outer leaf brickwork leading to the wetting of the insulation materials, increased damp penetration and a reduced thermal performance of the material. Poor construction methods, mortar and perp joints, debris within the cavities, dirty wall ties and poor installation procedures by installers all contribute to the overall problem, which generally will result in the need to remove the insulation, which is not only expensive, but will almost certainly cosmetically scar the building when finished. Unfortunately it doesn’t come out through the same hole through which it went in!
So how do you avoid this problem? Well there’s no easy answer to this other than to look carefully at the building’s construction (porosity of building materials) and its exposure to the prevailing weather conditions. If having then decided to proceed, ensure that the chosen contractor / installer, during the survey, checks the cavities and cavity trays for debris and dirty wall ties, but more importantly offers a system and material that guarantees (preferably insurance backed) that the materials being installed will not transmit / bridge moisture through and into the internal wall!
Alternatively, if you’re still unsure then don’t install.
Examples of Cavity Wall Insulation causing damp:
Cavity Foam Insulation
1970’s block constructed bugalow with poorly installed cavity foam insulation and debris bridging moisture via wall ties, cost around £800 to remove and rectify internal damage caused.
Polystyrene bead cavity insulation
Polystyrene bead cavity insulation 2
some comments
There are currently 25 of themreply
Rockwool has been inserted into our walls and damp has now occured, this was done back in the 1980s by a company called comben homes who built these houses, at present unable to put insulation into walls as it spits it out.
How do we get our houses re insulated and propely done and how can we seek advice.
Hi.
I am a cavity wall installer myself and if you have had your walls already insulated then you need to get in touch with the company that installed the insulation to investigate the problem.
Not being able to pump any more insulation into the wall is a good sign as it means that it has got enough in.
If you do not know the company that installed your insulation then you need to get in youch with CIGA and they should be able to help you.
Could you elaborate on what kind of damp you are experiencing, ie. is it a patch in a certain place, black mould, can you feel moisture on the inner wall. What room is it damp. Is it on a certain wall.
Most damp problems are due to cavity being bridged by rubble. When the insulation is pumped in, the insulation drops, hits the bridge in the cavity and causes a void where no insulation goes. This is what we call a cold spot and can cause damp due to the intensity of the heat from your house going for the cold spot and condensating.
Also just so you are aware. Dont let anybody try pump anything other than rockwool into your cavity if that already exists. You cannot mix insulations due to the differant U values and this can cause damp also.
To Sum Up… Contact company that installed in the first place. Or contact CIGA if you dont know who will help you as it should be registered with them as done and by who.
Hi,
I have been in the insulation industry for 9 years. My job is to train the field surveyors to check each individual property to determine whether it is suitable for receiving cavity wall insulation.
If anyone is thinking of getting their homes insulated you should bear in mind the following:
Always go with a reputible, well established company.
Make sure that a complete thorough survey is undertaken (this should include a boroscope check and combustion vent check)
Ask what material they use, It must be superior quality (Knauf Supafil mineral fibre will not allow damp or cavity bridging to occur under proper conditions)
A good company will also colour match the mortar in the drill holes.
And make sure they are backed by a 25 year C.I.G.A. guarantee. This ensures that should anything happen you are covered.
There are many benefits in getting your home insulated, including saving money on energy bills, more comfortable living environment, reducing co2, reducing carbon footprint, improving energy rating (EPC)
A company I would recommend is Mark Group – a national based company that does all of the above.
http://www.markgroup.co.uk
Thanks to those of you who have taken the time to respond and apologies for my late reply.
Whilst I have been surveying buildings for dampness for over 30 years, over the last 20 or so, I have seen a major increase in dampness reported in cavity walls and those where cavity insulation materials have been installed, these buildings dating from the Victorian period to as recently as the 1980’s.
Whilst I accept that debris in the cavity / or on wall ties will cause dampness to bridge a wall, in the vast majority of the cases I have surveyed (if not all), the dampness affecting the internal walls, plaster and decorations was caused by the direct impact of moisture (rain water) bridging from the outer walls to the inner wall – via the insulation material, whether it be foam, blown wool / fibre or poly beads.
In every case as soon as the insulation material was removed the walls would dry down, but unfortunately the cost of removing these materials can be extortionate, depending on the building and more importantly can also cause irreversible visual damage. Assuming that the company responsible for the original installation is still trading, then these costs may well be there responsibility / or claims should be directed to the CIGA insurance scheme, assuming covered?
In my experience some properties are not suitable for cavity insulation and in most cases are not properly surveyed to assess their suitability or their standing or exposure in relation to the prevailing weather conditions. Cavities are not checked for debris, air bricks not checked, walls simply measured x £ (meter rate) and that’s the price of the job!
How do I know, well my elderly neighbours just had a quote and I sat in on the Sales pitch!
As I have stated in my earlier case studies, there are millions of properties that have and will continue to be insulated (particularly in the current climate and concerns about global warming etc) and most of these will probably never experience any issues relating to dampness, but I can assure you many will.
My walls are and will continue to be an insulation free zone. Cold and damp walls won’t insulate my home or save me money!
PC
Hello, I hope you can advise me on my house. I live on an estate built 2001-2003. The houses were built with 100 mm cavity walls. Some of my neighbours have just had their walls insulated with rock wool. All the houses are detached. I am concerned that filling the cavities with insulation could cause damp. Is a 100mm cavity suitable for this?
Thank you for your help .I am now getting in touch with CIGA.My problem has caused me to have my roof overhauled twice and then taken off redecked lined and covered.£3.000.00 later(THATS JUST FOR THE ROOF) Two ceilings falling down, damp in the bedrooms- dripping water -cold spots-damp down stairs-re-decorating .Water dripping from windows.Rendering falling off – guess what it is not my roof.Its the w.c.i.yes the water is bridging the gap and going over my ceilings and down the inner wall It has not saved me a penny but cost me an arm and a leg.Thank goodness for this page.
In response to Peter’s question, don’t assume that having a wide cavity will make the difference, as I’ve dealt with several jobs with extra wide cavities and they had lateral dampness, through the insulation material.
I think it’s all down to the density of the material, the installation procedure and more importantly the exposure of the walls to the prevailing weather conditions.
If you do decide to insulate make sure you use a reputable company and take out the insurance backed guarantee!!
PC
Janet,
What can I say…………….give me a ring if you need further help or advice!
PC
I have had a damp problem with mineral fibre CWI. I am covered by the CIGA guarantee but 13 months after first notifying them, I am still waiting for the material to be removed!
I have had a damp problem with mineral fibre CWI. I am covered by the CIGA guarantee but 13 months after first notifying them, I am still waiting for the material to be removed!
They have admitted liability but the guarantee only covers up to a value of £10000.
Hi,
My house was built in 2002, the cavity wall consisting of brick and Thermalite blocks. I recently contacted the building company (Persimmon) to enquire if CWI was installed during the build. They said no, but as they had used Thermalite blocks in construction, they should provide adequate insulation, so advised against the cost of having CWI.
Our house is an end-terrace and the lounge and master bedroom are on the end wall. Both get very cold in winter, so we thought whatever Persimmon had said it had to be worth £149 to have CWI and make this 25-35% energy saving that seems to be quoted everywhere. I’ve just been contacted by Mark Group to have my survey next week. I’ve also just been reading some horror stories about damp problems.
What would you recommend for me to do? Does my modern house need CWI, or should I stick with my cavity and Thermalite blocks?
Hi
My mums house was built in 1999 and the cavity walls were insulated with polystyrene boards. She is now experiencing serious condensation on one gable end and one builder has suggested blowing in bead insulation to try and push the polystyrene back against the internal wall. But can you mix these types of insulation? any advice would be greatly appreicated
Today my house was surveyed for its suitability for mineral fibre CWI which, should we chose, will be installed free of charge under a govt scheme. I was informed that this material would not affect moisture levels despite the outer skin being penetrated by January by driving rain. It has a water proofing agent in it, however under worse conditions such as water pouring in it won’t prevent water reaching the inner skin, on the contrary, I’m sure. My wife was later contacted at work to say we are eligible and do we want it? She said she’d ask me…. we live in the Outer Hebrides (Isle of Lewis) where the rain seldom touches down, it moves so fast. Half the house dates from the 1880’s with walls built 5 ft thick, packed with clay/subsoil. 10 years ago we built an extension, this is the focus of debate – should we insulate or not?
I can’t advise you whether you should insulate the walls of your property, it has to be your decision. I can only give you the benefit of my 32 years experience in dealing with damp walls caused by the introduction of varying types of cavity wall insulation.
As I have said many times before “there are millions of homes that may have benefited for CWI that will never have a problem with damp, buts there are many that will”
PC
Peter
There is no reason why you can’t add poly beads to the wall where you’ve already got polystyrene boards, although I wouldn’t add any other system and would suggest that the beads are bonded.
Introducing additional materials doesn’t however necessarily guarantee that you won’t still get condensation.
PC
hi all
i,m a brick layer , would just like to say to the people thinking of having cwi who live in modern houses ie 2001 and later, dont bother! the levals of insulation already in the walls should be more than good enougth already, cavity plus celotex cliped in place is as good as its going to get i would just put more loft insulation in.
as for the damp with cwi i would look at the materials the exposed outside walls are built from and how pourus
they are
i live on a 1960s street where 90% of the houses have now been done with no problems.
i am about to have my own property done. after years of cleaning and clearig cavities at work it does seem to go against the grain to fill them but im going to take the chance as the house is so cold compared to modern houses with high levals of insulation.
Hi hope someone can help!Had a leaking boiler that has sodden inside cavity wall through to downstairs bedroom and bathroom.Insurance is paying for builder to replaster etc but I am concerned that any insulation will be rot (insurance will deal with this too).Do I call someone to take it all out, or do I get someone to take out the bad stuff and refill with new stuff, or do I let it breathe and not refill at all after reading that insulation can cause more problems?Don’t really know what to do as I don’t want mouldy stuff left in,and not sure if I want new stuff now!Thanks Emma
We have recently moved into a 1950’s bungalow, its only about 300mtrs from the sea.
Built of brick and at present no damp at all. The floors are not concrete so there are vents so that air can circulate under the floorboards.
We have been asked if we want cavity wall insulation free of charge and after reading other posts here I am now concerned and not sure what to do.
Also as strange as it may sound we lived in a property about 25 years back, a new property and we had cavity wall insulation, not sure what type and within months I became ill. I was told after some time it could have been the cavity wall insulation effecting me.
We moved not long after and my health improved.
Can someone have a reaction to cavity wall insultation.
Hi my parents had CWI installed about 13 motnhs ago by a company in Cardiff called Miller Pattison.
13 motnhs later damp has appeared in the living room which is the pine end of the house house. This side of the house faces the prevailing wind and rain etc. The type of insulation used was the wool.
Since the damp appeared my father has removed bricks etc and found the cavity was full of debris and rubbish. This is despite the company saying they checked the cavity and it was deemed fine to proceed.
The company have offered to remove the insulation and meet all costs including decoration etc.
However some people including the local building inspector are saying that its not the insulation causing the damp and not to remove it as it is serving a purpose by being in there
what would you advise etc ?
Peter Haywood26 July 2010 at 11:57 ampermalink
Hi,
I have been in the insulation industry for 9 years. My job is to train the field surveyors to check each individual property to determine whether it is suitable for receiving cavity wall insulation.
If anyone is thinking of getting their homes insulated you should bear in mind the following:
Always go with a reputible, well established company.
Make sure that a complete thorough survey is undertaken (this should include a boroscope check and combustion vent check)
Ask what material they use, It must be superior quality (Knauf Supafil mineral fibre will not allow damp or cavity bridging to occur under proper conditions)
A good company will also colour match the mortar in the drill holes.
And make sure they are backed by a 25 year C.I.G.A. guarantee. This ensures that should anything happen you are covered.
There are many benefits in getting your home insulated, including saving money on energy bills, more comfortable living environment, reducing co2, reducing carbon footprint, improving energy rating (EPC)
We had cavity wall insulation put in through a grant about ten years ago. We are not sure of the name of the firm, or whether we have a guarantee.
Last year, the stream at the back flooded and the level of water around the house was higher than the damp proof course for about an hour.
We have not noticed any problems with damp, but have had a surveyer round who has indicated high levels of damp in certain areas.
I am concerned that the insulation will have got wet and with no air circulating, it will not have a chance to dry. What would you recommend? Should we remove bricks in the damp areas and see what is happening inside? If so, who should we get to do the work?
Many thanks.
Jane
Hi Jane
The answer is yes, its better to check now so that you can take appropriate action!!.
You could remove some bricks or use an optical endoscope which will initially be less destructive.
If the insulation is wet you may have to consider its removal, although you need to take specalist advice.
Where are you located?
PC
Im having problems with wet and dense cavity wll insulation . I contacted CIGA, who informed me that the work must of been done before 1995 so they have not got my details on their registar so they can not help me. HELP WHAT DO I DO NEXT.
Hi Teresa,
There may be nothing you can do. Was the work done before 1995? Do you know who the contractor was?
If you have no sucess you may have no option than to simply remove it at your own expense. You may however not need to remove all, it depends on the extent of the problem. Good investigation work required by suitable specialist.
Ring me if you need to discuss further.
PC