Cavity Wall Insulation

[JtB]

Knowledgeable CC'ers,

I'm looking for guidance on finding a reputable cavity wall insulation company. I live in the Hampshire area and have contacted a number of companies including a Hampshire based company which has the highest rating on Checkatrade. However, this company turned out to be (in my opinion) a complete bunch of cowboys who I wouldn't let anywhere near my home. Their sales person turned up and carried out a 1 hour assessment of my home, then without a word of explanation handed me a contact to sign for proceeding with the order subject to referenced "terms and conditions". When I asked to see a copy of the referenced "terms and conditions" he told me that there were none based on the fact that it would be "free". He also told me that it would take about 14 days for the grant application to be processed but when I then spotted the "notice of right to cancel" hidden away under the contract it indicated that I had a maximum of only 7 days should I wish to cancel the contract. I then noticed that the sales person had falsified the year of build of my home as 1995 even though I had explicitly told him the property was built in 1997. When I highlighted this discrepancy he mumbled something about me not worrying and that he would sort it out. I then pointed out to the sales person that he was being a bit presumptuous expecting me to sign a contract when he hadn't even explained what work they intended carrying out and what type of insulation material (for example) they would be using. Only at that point did the sales person mention that they would be using "poly beads" which were well proven and that the work would come with a 25 year warranty backed by the government agency CIGA. In fact I remembered something on the internet when I was doing my research that CIGA have a strong track record for ignoring and resisting claims against their guarantees which may be something to do with the fact that CIGA are not a government body or even an independent industry body since the directors for CIGA LTD are also appointed directors for some of the major insulation companies.

Later when the above mentioned company called me back to enquire why I had refused to sign the contract I asked if there was any significance in a build date of "1995" and was told that houses built after 1995 would not qualify for a grant. When I informed the caller that the sales person had falsified the date on the contract as 1995 he told me that he shouldn't have done that and that he was probably just trying to help me out. Needless to say I shall not be considering that company, however I would still appreciate help in identifying a reputable cavity wall insulation company. I would also appreciate any feedback on the relative merits of poly beads, white wool and Rockwool as insulating materials.

Many thanks in advance for any guidance.

 

[annedonnelly]

There are lots of government/council supported schemes about at the moment. Does your local council have a list of recommended installers? My cavity wall insulation was done many years ago so I can't comment on recent stuff, but I've had no problems with mine.

 

[raleighnut]

Are there any "reputable" insulation companies in existence, also AFAIK any houses built after 1995 have cavity wall insulation built in when they were erected hence the cut-off date (I may be wrong but I'm sure that is when the building regs. changed, assuming the house was built to building regs that is)
@Archie_tect may know a lot more than me.

 

[midlife]

Why do you want insulation? Just curious as I thought by then your house would have thermalite blocks or similar? Just curious.

Shaun

 

[TissoT]

I can nt remember if they where insulated or not at this time . its just on the boarder line I think
I used to work on new builds (site work joiner).
if a test hole was drilled and a camera poked in at the time of the survey .
http://www.theguardian.com/environment/ethicallivingblog/2008/may/09/teeadlightlyinstallcavityw

 

[Archie_tect]

depends who built your house.

It may even be timber framed, you can't assume the cavity wall is built with masonry or that the cavity doesn't already have partial or whole cavity filled batt insulation within it.

RN is correct, the Building Regs changed in 1995, bringing in much lower 'U-values' for walls, floors and roofs. I think it came down to 0.35W/sqm.degK... so the walls will already be reasonably well insulated already [in 2005 it lowered again to 0.28, we work on 0.2 or less with modern timber frames]. Recent changes have lowered it again.

To be sure can you check who built your house JtB and you can track back to see what the specification was that they were using.

We don't specify polystyrene beads either but that's personal choice, as they often have a glue in the mix to bind them in place [otherwise they fly everywhere] which could bridge the cavity across wall ties allowing water to track across to the inner leaf.

 

[User6179]

I would think a house built in 97 would have cavity wall insulation , I built an extension in 98 and I have 65mm thick insulation in the cavity( Scotland).

 

[Archie_tect]

I can nt remember if they where insulated or not at this time . its just on the boarder line I think
I used to work on new builds (site work joiner).
if a test hole was drilled and a camera poked in at the time of the survey .
http://www.theguardian.com/environment/ethicallivingblog/2008/may/09/teeadlightlyinstallcavityw

Have you still got a copy of the survey from when you bought it? If they did a cavity inspection that would be fantastic!
Alternatively look on line for the planning permission for your estate's approval which should list the house builder if they were the applicant.

You could ask to see the Building Regs approval in your LA Council records but they may have ditched them by now and it would be a slog to track down.

 

[JtB]

One of the cavity wall insulation surveyors confirmed that our cavities do NOT currently contain insulation. As I recall, our house was built using thermal breeze blocks so the walls probably already meet the required 'U-values' of the day. However, we are seeing 'Pattern staining' on the insides of some of our external walls due to the mortar between the breeze blocks forming thermal bridges to the cold cavity. Our internal dividing walls are also solid blocks and we are not seeing 'Pattern staining' on any of them. Furthermore, some of our neighbours are also seeing similar problems even where their walls have been papered. I'm therefore looking into cavity insulation to warm up the cavities to see whether we can eliminate or at least improve the 'Pattern staining' problem.

Some great feedback here from you all, many thanks. I'm really glad we didn't get pressurised into going with polystyrene beads, so I guess that narrows it down to either White Wool or Rockwool.

 

[Archie_tect]

In 1997 they may have used insulated blocks with 25mm of foam insulation glued to the cavity side of the inner leaf blockwork... this would produce the pattern staining you have noticed. Thermalite lightweight pulverised ash blocks [which have a honeycomb like texture] can also cause pattern staining... but I'm really surprised they plastered the walls rather than dry-lining them- mind you plaster seals the walls better as it fills all the holes in the bclockwork [edit predictive text... clockwork indeed!] joints otherwise left open to leak expensive heat, which is good!

If the cavities are clear then I would prefer to use [proper] Rockwool cavity fill as their installers have a genuine guarantee and they'd CCTV the cavity first and they can thermal-image the external walls to check for cold bridges and gaps in the cavity fill where it needs topping up. They can drill holes internally if necessary which you can plaster patch which avoids seeing the hole patterns drilled in the motary joints externally. Not as cheap as other installers but you then get what you pay for rather than find there's bits of wall without any cavity insulation at all- and how could you tell?

 

[Archie_tect]

Here's the Rockwool technical data sheet from their website with a link to registered installers....
http://www.rockwool.co.uk/products/u/2014.product/9841/building-insulation/rockwool-energysaver®

If the cavity wall used thermal block inner leaf the cavity may only be 50mm thick which is the minimum NHBC requirement which means the cavity fill will not be as thermally efficient as a wider cavity- if you drill a hole through from the inside [in a discreet place that you can fill after] use a length of coat hanger wire with a 90 degree 'L-shaped' bent end so that you can check how thick the inner leaf is and how wide the cavity is to the inside of the brick outer leaf... ideally the cavity will be 75mm wide, 50% better than 50mm but then 50% more expensive to fill than 50mm, which will significantly improve the 'U- value', but you will get what you pay for!

 

[JtB]

Thanks @Archie_tect. I'm more concerned with the long term cost than the immediate installation cost. A free installation today could turn out to be very costly long term if it ends up compromising my cavities and since my house is the biggest investment I shall ever make then I would sooner pay more for the installation and get the job done right.

 

[Archie_tect]

A call to Rockwool [Technical Dept in Wales] will answer any queries you have and probably give you 2 or 3 local installer contacts to speak to.... give them the information you know about and get them to visit- they'll check the cavity themselves.

Edit!!
Local area advice about installers......

 

[Profpointy]

I'd be inclined to give the whole thing a miss. Fair enough to roll out a foot of insulation in the attic, and other non-invasive ideas, but retro-fitting insulation into a cavity not originally designed for it - not so sure. If you get dampness you're buggered - as you're not going to be able to remove it. Add to this you've got an industry full of shonky salesmen chasing grants.

 

[Smokin Joe]

I'd be inclined to give the whole thing a miss. Fair enough to roll out a foot of insulation in the attic, and other non-invasive ideas, but retro-fitting insulation into a cavity not originally designed for it - not so sure. If you get dampness you're buggered - as you're not going to be able to remove it. Add to this you've got an industry full of shonky salesmen chasing grants.

I'd agree. The internet is full of horror stories and R4's You and Yours consumer programme had some very sad tales a couple of weeks ago. The potential aggro wouldn't be worth what can only be a fairly minor benefit at most.