Cavity Wall Insulation

Discussion in 'Builders' Talk' started by Shaunf, Apr 25, 2015.

  1. Shaunf

    Shaunf New Member

    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.
     
  2. Gatt

    Gatt Active Member

    Good
     
  3. tom.plum

    tom.plum Screwfix Select

    if you have a cavity i would recommend you don't fill it with anything, it is there for a reason, if its constructed correctly, there is a constant stream of moving air that is in itself a thermal barrier, its also ventilation, filling it with polli balls will cause long term damage and the will be a national campaign by lawyer firms suing there ' we'll fill your cavity ma'm ' profiteers very soon,
    Who do you trust the most, the builder who built your home or the call centre paper shufflers and their promices,
     
  4. Mr Rusty

    Mr Rusty Screwfix Select

    Think twice. I will not have cavity wall insulation. The outer leaf of the brickwork is designed to be porous, and water may run down the inside of the outside leaf. That's why we have cavity tray, drip vents, and drip points on wall ties - to stop water crossing to the inner leaf. The idea of putting any bridge in the cavity across which water might flow to me seems crazy. I know of a couple of people who have damp issues following cavity wall insulation.
     
  5. Hi Shaun.

    Possibly slightly biased info above. The vast majority of homes having had CW insulation have had no side effects - other than reduced fuel costs.

    In fact Which says it's the most cost effective improvement you can do to your home. And there's every chance you can have it done for free, regardless of when your house was built.

    BUT, there are some houses which can be more liable to being affected by damp than others. These are ones in very exposed, wet areas usually down the West of the country, and - obviously - any with dodgy render/ pointing etc.

    The "constant stream of moving air that is in itself a thermal barrier..." mentioned above is not really a thermal barrier. It's not a thermal barrier precisely because that 'moving air' takes away the heat that's come through the inner skin - although it is naturally better insulated than a solid wall.

    CW works by trapping that air in the cavity, so that it does stay still and act as effective insulation - air is a terrific insulator.

    So, the chances are it'll be a good move to have CW insulation. But you need to ensure that your house is suitable as mentioned above.
     
  6. Phil the Paver

    Phil the Paver Screwfix Select

    I'm with Tom and Simon on this one, your house was built in a time frame when cavity insulation was widely used, if you haven't got it, it's for a reason, filling may cause you untold problems in the future, mainly damp due to condensation through lack of airflow.
     
    FatHands likes this.
  7. Hmm, I'm all for reasoned discussion, but not too keen on jumping to conclusions.

    "...if you haven't got it, it's for a reason..." What are you saying this reason is? I can think of a few - like it cost a lot back then, or the owners didn't think about it, or energy was cheap back then, or... etc etc etc.

    Out of all the possible reasons, are you saying it's because it would cause damp problems? If so, you back that assertion up with what?


    "...filling may cause you untold problems in the future..." Yes, it might. As it has done for a small number of houses. A very small percentage. Which is why each home should be surveyed with care - the prevailing weather conditions, how sheltered it is, what condition of the walls are in, etc.

    But the main problems that will be caused for the vast majority of homes is that the owners may become alcoholics due to the extra disposable income...

    Ok, ok. But seriously - a few scare stories does not maketh a poor idea. It is not snake oil. If your house is reasonably well built and ain't perched on a cliff top in the Utter Hebrides, then it will almost certainly be a good idea.

    (My house is a 30's 'bungalow' and sits facing the west coast in North Devon - the sea is in direct view less than a mile away. Some of the winds that hit us makes the roof shake and my teeth rattle - and we have c-w insulation fitted by the previous owners (it looks like a set 'foam') which has not caused any issues whatsoever.

    Shaun, do your research (as you are doing) and consider reasoned arguments...
     
  8. tom.plum

    tom.plum Screwfix Select

    air needs to move
    that statement is hard to prove or disprove without any variant conditions,In the 50's and 60's houses where built with the traditional cavity, 2 brick walls with a cavity vented top and bottom with airbricks, imho the very best and never bettered,to fill them is sacrilege, the bricklayers went to great trouble to keep them free of cement snotters and rubble because they understood why that cavity is important to keep clear, later on standards slipped,builders used clicker blocks and breeze block and bricklayers stopped clearing the cavity and it became less affective, So if you own a home which was built up to about 1965 and you fill the cavity you will go to hell and recieve the worst punishment ever from the time served brick layers of the post war builders federation leader Mr Benn Doon and his Co- administrator Phil Mc Cavity, :(
     
    Gatt likes this.
  9. :)

    Ooh-er, I'm in trouble then... :oops:
     
  10. KIAB

    KIAB Super Member

    Had cavity wall insullation at a previous place, nothing but grief, will never have it again.
    Damp patches on walls, mould, etc, ended up opening up wall to find insulation had fallen,sunk down to the ground floor & had become totally waterlogged mess, ended up having to take out bricks here & there on the ground floor & sucking out the soaken mess with wet'n'dry hoover.:mad:
     
  11. Shaunf

    Shaunf New Member

    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.

    [​IMG]
    Some great feedback here from you all, many thanks. @KIAB, as a matter of interest which type of insulation did you have installed in your last house?
     
  12. Nice hoosie, Shaun.

    Am I seeing horizontal lines of 'damp' in that piccie? If so, Blimey.

    I'd suggest you get local independent damp advice for your issues - this has to be a 'known' condition for this type of build.

    However, at the risk of further upsetting the nae-sayers above, I'd have thought that your house, being a fairly recent build, will have an outer brick/block skin in very good order (so very little chance of rain-driven moisture), and therefore a good candidate for CW insulation.

    However, the best way to insulate external walls is to line the inside - but I can imagine that's not an attractive idea for you as you have coving etc.

    There is, however, a 3mm-ish thick insulation roll - I forget what it's called, a 'Rockwool' type stuff or summat (it was mentioned on the "insulating a connie" thread).

    But, proper independent advice. Someone who comes in and says "I know exactly what cause that - I've seen it on many houses around here - and I know exactly the best options to sort it"

    Rather than the genuine scare stories on here, or me saying 'no prob - do it...'
     
  13. Shaunf

    Shaunf New Member

    No, the walls are perfectly dry. This is 'Pattern Staining' where ghost images of the breeze blocks become visible in the wall due to very fine dust particles collecting on the markedly cooler surfaces where the mortar between the breeze blocks acts as a thermal bridge between the cold cavity and the room. So the idea behind warming up the cavity is to make the temperature across the surface of the wall more even thereby eliminating or at least improving the effects of 'Pattern Staining'.
     
  14. KIAB

    KIAB Super Member

    Some white fibre fluff, was blown in, after about 3-5 years a few damp patches appeared along bottom of dinning room & living room walls.
     
  15. Blimey, Shaun, that's a new one on me.

    I never knew that cold patches could attract fine dust like that.
     
    Jitender likes this.
  16. Phil the Paver

    Phil the Paver Screwfix Select

    Those mortar lines on your walls is down the a lack of plaster, it has nothing to do with thermal bridging, you'll do more good by fitting plaster board to that wall, than you will filling the cavity.
     
  17. Shaunf

    Shaunf New Member

    That's what I wondered to start with, but then why would we not also get this pattern staining on our internal walls which are also solid block walls. Also, why would our neighbour get this patten staining on the surface of his wallpaper?
     

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