Cavity wall insulation

Discussion in 'Builders' Talk' started by Diy Darren, Feb 26, 2004.

  1. Diy Darren

    Diy Darren New Member

    This may appear a stupid question but please ignore my lack of basic building knowledge!!

    I am currently replacing the window cills into several rooms in my house (1950's, brick, no cavity insulation) whilst I have access to the cavity can I 'stuff' wall insulation of the woollen variety into the cavity? Does it have to be held back against one side as with the board type insulation or does it just fill the cavity - is there a damp crossing problem??? Finally will this have any effect or could it cause more problems than benefits due to the 'partially filled void'??

    Any response greatfully recieved.
  2. The Trician

    The Trician New Member

    I was going to post something like this query myself - Ta DIYD! My house is bl00dy freezing at the moment and I'd wondered about cavity wall stuff. I was worried about damp-proofing being undermined too. I am also concerned about the type of stuff they use - is it chemically safe? Or will we be having a 'scare' in the future similar to asbestos. I can already see a head of steam building up about the use of MDF - all the Free Radicals being given off from the woodglue solvent etc. I won't have the horrible stuff in my house.
  3. Dewy

    Dewy New Member

    I had my walls done on a full council grant. They blew some mineral fluffy stuff in every 3 feet along & up the walls. The energy saving grant was more than the work cost so they made it up with some low enerby light bulbs when they were new & very expensive. That was over 10 years ago & I have never had any damp problems.
  4. bodget&scarpers

    bodget&scarpers New Member

    well this may help a little bit?
    but it may take a while 2 do!!!!!!!!
    wicks sell this loose fill insulation,but the package looks like wool bats.when u open it is all compressed so u just grab a handfull and drop in 2 cavity,u can also put a small battern in cavity 2 drop the stuff further away ,then flick it around in cav,then iv u got access to the top coarse of bricks in loft do the same up there!
    or do wot dewy did.
  5. oggie

    oggie New Member

    Sorry to burst your bubble guys but the cavity was invented for good reason to allow free airflow between two walls allowing a damp wall outside and a dry wall inside and no condensation in between ask yourself the question is it not better to insulate the drywall? being in the damp buisness i have recently removed patio doors to find cavities full of soaking wet fodder my house is ex council which has the blown stuff and dampness has shown at all windows and doors
  6. bodget&scarpers

    bodget&scarpers New Member

    eer, so wot about rat trap bond!!!!and yes it was widley used.
  7. Thermo

    Thermo New Member

    Why not get it done properly. british gas offer a subsidised installation, with intrest free credit for up to three years. It cost 240 to get my place done and you pay £6 a month, basically the price you will save on heating bills by having it done. As for damp problems, i had quite a few before installation, but not now
  8. Dewy

    Dewy New Member

    I'm glad I had my walls done. My gas bill dropped quite a bit.
    My only problem was the air vent in the wall that was done when the gas fire was installed. This was merely a couple of bricks knocked out & covered with vent covers. The insulation company rolled up a piece of card to keep the vent clear. As it's behind my chair I suffered a lot of cold draughts on my feet. I cured the problem by making a duct feeding from the vent to the side of the fire along the skirting board. Now the fire gets a good supply of fresh air & I have lost the draughts.
  9. oggie

    oggie New Member

    Only one answer its carp!(^_+)
  10. catcoddler

    catcoddler New Member

    Trician - if you find yourself inexplainably lusting after some MDF, I think there is a liquid you can get, which brushes on to the stuff, whcih effectively seals it so it doesn't off gas. I seem to remember the same compaby sells a paint which absorbs VOC's. If you want me to dig out the company, let me know. You're absolutely right in keeping this #### out of your house. There is a very good book on the dangers posed by most runof the mill household goods/materials - if you want details, lmk
  11. Malcy

    Malcy New Member

    Scottish Power (check google for web address) will give you at least a 50% grant (receipt of no benifits) up to 100% if you get certain types of benifits.

    Blown mineral fibre which has a chemical treatment to resist absorbing water is the stuff to be using. The good news is if it all goes wrong and water is penetrating across the caity it can be sucked out again.

    The cavity is thee for a good reason (to keep the rain out). If you are on top of a hill, or other exposed location forget it. A render and decent overhangs at the eaves help to protect the walls making cavity ins. less risky as does a wider cavity (a few are 75mm, most are 50mm).

    Hope that helps.
  12. Rog

    Rog New Member

    Must agree with Oggie's post,this time of year I can spot the position of the wall ties from inside a customers house by the damp spots on the wall!(quite pretty patterns they make)

    I have on a few occasions been asked to quote for re-pointing the external brickwork of houses,this has arisen because the householder has complained to the cavity wall insulation firm about damp patches on their walls,the firms excuse is to tell the customer that property needs re-pointing! This has proved to be absolute rubbish,bricks & mortar absolutley sound.

    The cavity should be left clear to do it's job,you can not get the stuff out once it's been injected.
    Look at alternative insulation or pay the extra heating bill is my advice.

    PS I would not purchase a property if the cavity had been injected,I was taught to keep the cavities clear on site the hard way although a good Lufkin tape is still in one.
  13. The Trician

    The Trician New Member

    Trician - if you find yourself inexplainably lusting
    after some MDF, I think there is a liquid you can
    get, which brushes on to the stuff, whcih effectively
    seals it so it doesn't off gas. I seem to remember
    the same compaby sells a paint which absorbs VOC's.
    If you want me to dig out the company, let me know.
    . You're absolutely right in keeping this #### out
    of your house. There is a very good book on the
    dangers posed by most runof the mill household
    goods/materials - if you want details, lmk

    Cheers meowd, I HATE MDF cheap short-cut stuff - same as that crappy chipboard flooring they use in new-builds - HATE that too:) Drop us the book title - I'd be interested to read more.
    Cheers

    TT
  14. wardoss

    wardoss New Member

    Oggie

    I have a 1960s council house with uninsulated cavities and recently on one of the wet and windy days water was dripping down from the head of the window on the exposed gable wall.

    Recently replaced windows and the seals are all in A1 condition. What do you reckon.

    When wet the bricks (which are an LBC) shine slightly, i think water is seeping throught the bricks and dripping down the cavity. Pointing in places is not 100% either
  15. oggie

    oggie New Member

    A land of many things
    Q Did it drip before the windows went in?
    q Is there a window above that window ?
    Q Did they take out all the cavity closers and DPC when they put the new windows in ?
    Q were the new windows put in and sealed on a rainy day?
    Q do you have any slates missing ?
    answer theese and i will get back to you
  16. wardoss

    wardoss New Member

    Thanks Oggie

    Firstly windows installed myself.
    No window above this.
    No cavity closers were taken out.
    It was a wetish day when we installed them
    No slates or tiles missing
    The wall is quite exposed and there is a solder course of bricks above the window.
    There was no drip before or since, just one day when it was really hammmering it down.
  17. oggie

    oggie New Member

    Ok then !
    As you say the roof is sound then your only entry is through the pointing or a cracked brick

    Check top of soldier course to see if it dropped when you took out old window if so ......................repoint
    Check for any cracking in bricks .........take out repoint
    If after that or even if you dont see any cracking spray wall with Water repellant silica and allow to dry On a dry day spray from highest point and allow to run down wall face till it soaks in make sure whole face is covered equally also recheck your sealing round windows to se if its lifting as silicone does'nt stick in the damp any problems give me a shout
  18. wardoss

    wardoss New Member

    Thanks Oggie

    I'm gonna wait until the summer and when the wall is complete dry and repoint, waterseal and probably reseal round windows.

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