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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthorrsk1
    • CommentTimeAug 25th 2019
     
    Victorian house, wooden floors. I am debating whether to pull up the boards in my dining room in order to insulate underneath. Originally I was planning to replace a few knackered boards and then sand the floor and have it bare, the floor is generally in not too bad nick. But now i am wondering whether i should pull it all up as this would mean i could get 50mm PIR between joists, lag the pipes etc. It's 4 x 4m so a big area
    What to do ? it would be great to have insulation, but it's a lot of timber and I doubt the boards would survive being pulled up, so they'd end up as firewood: seems a bit destructive/wasteful. Plus I would much rather have nice old boards than crappy new pine ones. I could keep the old floor and try hard to fill all gaps to reduce draughts, but its a leaky old floor and it would be hard to do well. Anyone have any opinions what I should do? Other options I could consider?
    • CommentAuthortony
    • CommentTimeAug 25th 2019
     
    Can you get to the underside of them via a crawl space?
    • CommentAuthorrsk1
    • CommentTimeAug 25th 2019
     
    <blockquote><cite>Posted By: tony</cite>Can you get to the underside of them via a crawl space?</blockquote>

    no, that's the problem
    • CommentAuthortony
    • CommentTimeAug 25th 2019
     
    I would fully fill the void with lightweight particulate insulation, vermiculite or polystyrene beads

    Happy to help
    • CommentAuthorrsk1
    • CommentTimeAug 25th 2019
     
    that would be around 5 m3 of vermiculite. And would block ventilation of the space, so not a good idea
  1.  
    I'm doing something similar at the moment. I lifted a group of 4 boards, and will shove insulation as far in as I can reach in both directions, using a prodder etc. Then lift another group of 4 boards further down the room, and so on.

    I took a tip from GBF to use a hammer and punch to drive the nails right through the floorboards. So far they've all lifted without serious damage that way, and will be relaid.

    From previous experience it's definitely worth insulating under the boards, in all cases but especially if you are not having carpet, they are so cold to stand on otherwise. (Edit to add: is equally important to fix all air leaks aka draughts, your cold feet will detect if you missed any!)

    For the rooms with more space under the floor I will use wool-dangling-in-a-net stapled to the joists, but for the room with a really shallow floor void, it might need to be strips of PIR as I can fix these without getting an arm and shoulder in to staple the netting. This will be needed over the dwarf walls too.
    •  
      CommentAuthordjh
    • CommentTimeAug 25th 2019
     
    Posted By: rsk1that would be around 5 m3 of vermiculite

    Not quite sure what you mean by that, but perhaps you're suggesting it's a lot? We'd need to know the floor area to understand. By contrast 50 mm of PIR isn't a lot. Does it even meet building regs? Personally I'd look at EPS rather than vermiculite, and if you went for vermiculite or perlite make sure it is the type treated to be water repellent, not the natural types used in agriculture for their water absorbtion properties.

    As for the ventilation aspect, you've been a member for a while; I'm surprised you haven't seen any of Tom Foster's posts about full filling suspended floor cavities?
  2.  
    Rsk1 mentioned his/her floor area is 4x4m. I think 4 x 4 x 0.3m = 5m3.

    FWIW, building regs part L1B in England do not require you to install insulation, unless it has an economic payback within 15years. If the payback is longer than this (which it will be, if you include labour at sensible rates) then there's no particular requirement for any insulation thickness or value.

    I've been here a while, I like the 'fill your void with beads' idea, but am not going to touch it until at least another 100000 people have tried it first.
    • CommentAuthorrsk1
    • CommentTimeAug 25th 2019
     
    <blockquote><cite>Posted By: djh</cite><blockquote><cite>Posted By: rsk1</cite>that would be around 5 m3 of vermiculite</blockquote>
    Not quite sure what you mean by that, but perhaps you're suggesting it's a lot? We'd need to know the floor area to understand. By contrast 50 mm of PIR isn't a lot. Does it even meet building regs? Personally I'd look at EPS rather than vermiculite, and if you went for vermiculite or perlite make sure it is the type treated to be water repellent, not the natural types used in agriculture for their water absorbtion properties.

    As for the ventilation aspect, you've been a member for a while; I'm surprised you haven't seen any of Tom Foster's posts about full filling suspended floor cavities?</blockquote>

    I've now read lots of previous posts about insulating under suspended floors, which I should have done before posting myself. Couldn't find any about full filling though. could you provide link?
    • CommentAuthorgyrogear
    • CommentTimeAug 25th 2019
     
    Posted By: WillInAberdeenI like the 'fill your void with beads' idea,


    I blow my crawlspace with warm air from the house, via a small fan, and just let it vent outside through a small orifice; hopefully taking away any radon or other nasties that's down there...

    gg
    • CommentAuthorKenny_M
    • CommentTimeAug 26th 2019
     
    In my previous home, suspended timber floor, well ventilated underneath, I stapled the netting between the joists and put glass fibre insulation (long before I encountered GBF and the stuff was £3 a roll from B&Q at the time due to some energy company subsidy so was very cheap to do).

    The rooms were mostly carpeted, tiled or already had modern wood flooring over the top and be honest, I didn't notice any appreciable difference from adding the glass wool. I think its the draughts that are the worst thing in these houses, so bare original floorboards would be a different story. The floors in that house even before the insulation were a lot, lot warmer than my current 1990 extension with concrete slab and tiles.

    Also interested in the eps bead fill thing, hadn't heard that one before but have searched and found some of the threads. Off topic, but I remember reading something a while back about blowing eps in behind lath and plaster which sounded interesting.
    • CommentAuthorPetlyn
    • CommentTimeSep 3rd 2019
     
    Another alternative to EPS beads are glass beads - free flowing (can be poured or blown), won't be eaten by insects or rodents, fire proof and doesn't take on more than 15% moisture.
    • CommentAuthorRick_M
    • CommentTimeSep 5th 2019
     
    Is it possible to add an air barrier if you did take up all the floorboards? I guess you'd have to install a floating floor to avoid puncturing the barrier?
    • CommentAuthortony
    • CommentTimeSep 5th 2019
     
    It is always possible to install an air barrier
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