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Housing - Renovation: DIY-blow beads into cavity on lean-to conservatory?

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  1.  
    • CommentAuthora63245347
    • CommentTimeMay 22nd 2015 edited
     
    Hi All,

    I have a flat roofed conservatory lean-to extension. The wall that was the old external house wall is now the internal conservatory wall.

    I've discovered that there is no insulation in the cavity in this wall. The rest of the house has had CWI.

    So that means that the heat from the conservatory and the room on the other side of the wall is going into the cavity and up into the cold loft.

    I can get to the cavity from the top by sliding up the roof tiles and getting underneath the felt.

    I have had the following suggested to me

    1. "closing the cavity at the top of the wall" using expanding foam so that any heat doesnt rise straight into the loft
    2. "pouring" cavity insulation beads down from the top.
    3. blowing beads in using a vacumn cleaner blowing into a bag of beads and a spare hose on the other side of the bag into the cavity. I already have 2 big bags of fire retardent beads.

    The cavity is 50 to 60mm deep. The wall is about 7m long and single storey. I suspect it is too small for a commercial firm to be interested.

    Any thoughts on how best to treat this would be much appreciated. Thank you.
    • CommentAuthorgravelld
    • CommentTimeMay 22nd 2015
     
    Interested to see other responses because I'm going to do something similar to two walls which have been enveloped in extensions.

    My current plan is to do either 2 or 3, wait a few weeks for settlement, then do 1. I'll probably start with 2 to see how easy/fast it is and if it takes too long, 3.
    • CommentAuthortony
    • CommentTimeMay 22nd 2015 edited
     
    Pour in beads from the top and insulate up to join roof insulation with quilt after gears have finished settling.

    Edited: gears should say beads. Sorry
    • CommentAuthorgravelld
    • CommentTimeMay 22nd 2015
     
    I hope "gears" is not "years" :-D
    • CommentAuthora63245347
    • CommentTimeMay 22nd 2015
     
    I'm probably going to try 3 for the lower part, then 2 then 1 - mainly because 3 sounds fun and has the opportunity for disaster! But also because there is a blocked up window in the wall, and I want to get the beads underneath it.

    Good point Tony about revisting and topping up the insulation after settling.

    I was thinking of using a normal 1/2" garden hose pipe rather than a vacumn cleaner hose on the bag outlet for a bit more control and because the cavity is quite narrow.

    There are a couple of cables in the cavity that I need to remove 1st to prevent reaction.

    Is there any practical DIY way of adding glue somehow so that if the wall is drilled in the future the beads stay in it?
    • CommentAuthorskyewright
    • CommentTimeMay 22nd 2015
     
    Posted By: a63245347
    3. blowing beads in using a vacumn cleaner blowing into a bag of beads and a spare hose on the other side of the bag into the cavity.

    I think the usual arrangement is to have a "T" pipe, with the down stroke into the bag. Air is then blown into one end of the top piece, beads get sucked up by the venturi effect & air plus beads emerge from (a flexible pipe) attached to the other end of the top piece.

    Happy to be corrected...
    • CommentAuthorbarney
    • CommentTimeMay 22nd 2015
     
    If you can pour them in, then use a water mist sprayer with a bit of diluted PVA glue added as you pour in the beads - if you can just wet them, they'll stick OK

    Ditto if you have to drill the wall later - drill a small hole and then spray in some diluted unibond or similar PVA - then you can drill a larger hole without ending up ankle deep in polybead

    Regards

    Barney
    • CommentAuthorcjard
    • CommentTimeMay 28th 2015
     
    Sky right, that's the way my sand blaster works.. But then again the warmcel blower machine I saw on YouTube didn't seem to work that way.. Looked more gravity fed.
    • CommentAuthorskyewright
    • CommentTimeMay 28th 2015
     
    Posted By: cjardSky right, that's the way my sand blaster works.. But then again the warmcel blower machine I saw on YouTube didn't seem to work that way.. Looked more gravity fed.

    Many years ago (25?) and in a different place we had warmcell loft insulation installed & yes I think they fed the blower machine via a funnel like hopper? However, my comments above were about the polystyrene beads the OP intends to use, quite a different material to handle?
    • CommentAuthora63245347
    • CommentTimeJun 6th 2015
     
    I've now taken the lower roof tiles off.

    Plan is

    1. Tip polystyrene beads in the cavity (I'll leave the cables there for now - they'll be disconnected during redecoration in the next few weeks)
    2. Seal the top with expanding foam

    The next step is replacing the felt-on-ply with a warm flat roof.

    I'm planning the make-up as follows from bottom to top, after removing the existing felt.

    Existing Ply decking
    Self adhesive vapour barrier
    140mm non foil insulation boards
    EPDM cover

    Here's a pic of what I think I need to do where the new raised insulated roof joins onto the pitched roof.

    Remove fascia
    New vapour barrier over decking which extends to the right hand side to cover outer leaf of bricks
    Cut the insulation boards in between the pitched rafters and extend the boards all the way to the thermalite inner leaf. This will cover over the bead filled cavity
    Screw 18mm OSB lay board over pitched rafters, onto the tile battens. Board to extend onto insulation to provide a surface for the EPDM to stick to
    EPDM over the top
    Tiles back on

    Does this sound reasonable?
      Picture1.jpg
    • CommentAuthora63245347
    • CommentTimeJun 6th 2015
     
    another pic for perspective
      IMG_20150606_095759.jpg
    • CommentAuthorwoodgnome
    • CommentTimeJun 6th 2015
     
    If there is even the slightest breeze the beads will blow everywhere as you pour them in!
    • CommentAuthorchuckey
    • CommentTimeJun 6th 2015
     
    Don't seal the cavity top with foam, its too permanent. Use glass fibre.
    Frank
    • CommentAuthora63245347
    • CommentTimeJun 6th 2015 edited
     
    Beads are in, no drama. There was a reasonable breeze, but they went in like pouring water. I used some electricians cable pulling rods to "tamp" down the beads and try and spread them out at the bottom as much as possible.

    thanks for all the comments. Next stop tomorrow is felt roof off, and hopefully vapour barrier down.
      IMG_20150606_122313.jpg
    • CommentAuthortony
    • CommentTimeJun 7th 2015
     
    play some loud music, bang about and refill after a week and again after two, wait til no more settlement, i would pour in some highly diluted pva too.
    • CommentAuthorgravelld
    • CommentTimeJun 7th 2015
     
    Thanks for posting the pics!

    Any thoughts on the amount of glue mixture Tony, given the volume of bead?
    • CommentAuthortony
    • CommentTimeJun 7th 2015
     
    two half buckets 10:1 water to pva, I would use a watering can and hope it works, we spray the beads as they go in. :shamed: forgot to say earlier
    • CommentAuthorandyman99
    • CommentTimeJun 8th 2015
     
    Or, depending on how much access you have, get a sprayer with a long lance and poke it into the beads in as many places as you can. My thoughts when I did this was to create enough glued together beads to prevent the whole lot draining out if a hole is subsequently cut, never going to glue them all. I found the sprayer worked ok with a stronger mixture, closer to 3:1, but wouldn't want to argue with Tony on whats best.
    • CommentAuthorgravelld
    • CommentTimeJun 8th 2015
     
    Thanks! I'll have a scale that up about 2 or 3x for my project.
    • CommentAuthorAMG
    • CommentTimeJun 8th 2015
     
    Is there any risk of condensation forming in cavity now that there is no airspace? Hopefully vapour barrier on internal side will help but what if not 100% vapour tight?

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