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Old house attic insulation

  • 08-01-2020 10:08AM
    #1
    GreeBo
    Registered Users, Registered Users 2 Posts: 27,474 ✭✭✭✭


    Hey,

    I was wandering around my 70+ year old attic and discovered that the original insulation (50mm!) is laid across the joists rather than between them. It also appears that there is paper laid across the joists first and then the fibreglass.

    From what I can see this leaves huge gaps between the insulation and the ceiling below which I cant imagine is doing much for preventing drafts.

    So, i'm guessing that there is no point in me adding new insulation (200mm) on top of the existing since I'll still have these large gaps where the wind from the eaves is free to roam and I'm not actually insulating the ceiling at all.

    The existing insulation is pretty manky so I'd rather not have to remove it, but if I must I must!

    Also, I haven't seen paper under fibreglass before, anyone know what this is for?

    Cheers.


Comments

  • #2
    listermint
    Registered Users, Registered Users 2 Posts: 34,349 ✭✭✭✭listermint


    GreeBo wrote: »
    Hey,

    I was wandering around my 70+ year old attic and discovered that the original insulation (50mm!) is laid across the joists rather than between them. It also appears that there is paper laid across the joists first and then the fibreglass.

    From what I can see this leaves huge gaps between the insulation and the ceiling below which I cant imagine is doing much for preventing drafts.

    So, i'm guessing that there is no point in me adding new insulation (200mm) on top of the existing since I'll still have these large gaps where the wind from the eaves is free to roam and I'm not actually insulating the ceiling at all.

    The existing insulation is pretty manky so I'd rather not have to remove it, but if I must I must!

    Also, I haven't seen paper under fibreglass before, anyone know what this is for?

    Cheers.

    Fibreglass used to come packaged with the paper around it. So as you unrolled it it was there. The person installing this was obviously an amateur as they rolled it wrong for 1 and left the paper in situ 2.


  • #3
    GreeBo
    Registered Users, Registered Users 2 Posts: 27,474 ✭✭✭✭GreeBo


    listermint wrote: »
    Fibreglass used to come packaged with the paper around it. So as you unrolled it it was there. The person installing this was obviously an amateur as they rolled it wrong for 1 and left the paper in situ 2.

    That's what I expected but since it seemed so ridiculous I expected that there was some reason other then incompetence!


    It also explains why there are literally hundreds of metres of brown paper bunched up in my attic...:rolleyes:


    So I guess this install basically renders all this insulation (all 50mm of it) useless and likewise for any that I would be adding on top.

    I see hours of sweating inside a full facemask and a pair of marigolds in my future! :(
    Anyone know if fibreglass ok in a domestic bin or is it company dependent?


  • #4
    L1011
    Registered Users, Registered Users 2 Posts: 72,739 ✭✭✭✭L1011


    Bin company would not be happy with significant amounts of it; and 50mm thick from the entire attic floor surface of a normal sized house will be multiple bins worth. But it can go in a normal construction waste skip.

    The original insulation in my house, done right thankfully, was 25mm and they left all the bags up there for me to dig out when putting another 200mm over it. I doubt it did anything at all.


  • #5
    GreeBo
    Registered Users, Registered Users 2 Posts: 27,474 ✭✭✭✭GreeBo


    L1011 wrote: »
    Bin company would not be happy with significant amounts of it; and 50mm thick from the entire attic floor surface of a normal sized house will be multiple bins worth. But it can go in a normal construction waste skip.

    The original insulation in my house, done right thankfully, was 25mm and they left all the bags up there for me to dig out when putting another 200mm over it. I doubt it did anything at all.

    Attic is large so yeah I;d be looking at tens of bins worth.
    A skip seems like overkill, maybe a skip bag or two would work...


    I'm not even that bothered about what the existing is doing, more-so that, since its not 100% in contact with the ceiling below (its 50% at best and since its perpendicular and the paper is still in-situ, there are large air channels running end to end between each joist), it would render any additional insulation useless.


  • #6
    [Deleted User]
    Posts: 7,497 ✭✭✭ [Deleted User]


    No need to remove the old stuff.Just get it down properly .
    I'd move all the old stuff to one section of the attic and fill up between the joists. 3 layers of 50mm should do it.
    Then fill the rest of them with new stuff the correct thickness.
    After that you could lay another 200mm perpendicular to the joists when funds allow.

    Only recently fixed a bad insulation install in my own place and layed 200mm on top.
    It was a poxy job but the difference really is night and day.
    300mm is the current standard as far as i know.


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  • #7
    listermint
    Registered Users, Registered Users 2 Posts: 34,349 ✭✭✭✭listermint


    BrownFinger wrote: »
    No need to remove the old stuff.Just get it down properly .
    I'd move all the old stuff to one section of the attic and fill up between the joists. 3 layers of 50mm should do it.
    Then fill the rest of them with new stuff the correct thickness.
    After that you could lay another 200mm perpendicular to the joists when funds allow.

    Only recently fixed a bad insulation install in my own place and layed 200mm on top.
    It was a poxy job but the difference really is night and day.
    300mm is the current standard as far as i know.

    This!

    There is no need to waste money chucking it, it has a purpose. Recycling it in this way would be the best approach.


  • #8
    GreeBo
    Registered Users, Registered Users 2 Posts: 27,474 ✭✭✭✭GreeBo


    listermint wrote: »
    This!

    There is no need to waste money chucking it, it has a purpose. Recycling it in this way would be the best approach.

    It's pretty manky and compressed down to well under 50mm, more like 25mm in places.

    Also I'm not mad about having to move it twice, that fiberglass is a total bitch to work with.


  • #9
    listermint
    Registered Users, Registered Users 2 Posts: 34,349 ✭✭✭✭listermint


    GreeBo wrote: »
    It's pretty manky and compressed down to well under 50mm, more like 25mm in places.

    Also I'm not mad about having to move it twice, that fiberglass is a total bitch to work with.

    It's actually grand anyone that has problems isn't wearing full clothes and a mask and gloves.

    Get all the right gear put some headphones on and go at it. Be done in no time.


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