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Spray foam insulation in converted attic

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  • 21-09-2023 4:36pm
    #1
    banchang
    Registered Users Posts: 1,270 ✭✭✭


    A number of years ago we had our attic converted. My suspicion is that the insulation behind the plasterboard ceiling of the bedroom isn’t optimal, as the room gets v cold in winter, but there’s not a lot we can do about that now.

    However, around the sides of the attic we have crawl space which we use for storage. This space goes right around 3 sides of the house, & is approx 4 foot high, & 6 foot in a sloped apex from top to where it meets the floor. This space had roll out fiberglass insulation tacked between the rafters, but over the years this has fallen down & in many areas is completely bare now. As a result this area is v cold in winter, as is the bedroom. I would imagine that this cold also permeates to the rooms below through the ceiling.

    We are considering getting this small eave crawl space roof area sprayed with foam between the rafters - there’s nothing we can do about the ceiling within the bedroom as that is sealed up by the plasterboard. While we know it’s only a small part of the cause of the room being cold, we think that if we insulate it properly this should certainly help.

    Your thoughts & advice appreciated on this proposal, & any recommendations for contractors appreciated also.



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    #2
    zg3409
    Registered Users Posts: 6,707 ✭✭✭zg3409


    Fibreglass or glass wool is easiest and cheapest and could be done in a few hours. Get a few quotes and there may be grants too. You can also inspect the existing sloping insulation and it may make sense to destroy the ceiling in order to properly fix the issue. There are lots of general insulation guys that will give free quotes.

    Try get a photo of the attic space and try get a view of the sloping roof where insulation may be visible.



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    #3
    markw7
    Registered Users Posts: 363 ✭✭markw7


    This thread is warning about spray foam, I don't know if it applies to modern materials/methods just a heads-up.

    https://www.boards.ie/discussion/2058312417/video-on-spray-foam-its-20-minutes-but-worth-a-look




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    #4
    MicktheMan
    Registered Users Posts: 2,833 ✭✭✭MicktheMan


    The crawl space is supposed to be cold in that it is outside your thermal envelope. The floor and the knee wall however should be insulated well.

    However, the cause of the rooms being cold and unable to hold their heat is very likely due primarily to significant air leakage common to these type of structures. Therefore, sprayfoaming the rafters will likely be a waste of money, not to mention the concerns raised above by @markw7.



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    #5
    Sue de Nimes
    Registered Users Posts: 151 ✭✭Sue de Nimes


    There is a good article below from Which? in the UK which covers a lot of the pros and cons


    https://www.which.co.uk/reviews/insulation/article/spray-foam-insulation-ajTlp7t5K7lT



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    #6
    jasgrif11
    Registered Users Posts: 434 ✭✭jasgrif11


    @MicktheMan If it’s a reputable company doing the spray foam with vent cards throughout is there still a major concern?

    I suppose i’m asking if its the product itself or how its applied?

    I noticed issues in the UK with Mortgages for houses with Spray foam, but haven’t heard these happening in Ireland (yet).

    The reason I ask all this is that im considering a combination of spray foam and Cellulose in my attic as an upgrade to my 1.5 storey 2008 home.

    Thoughts?



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    #7
    MicktheMan
    Registered Users Posts: 2,833 ✭✭✭MicktheMan


    im considering a combination of spray foam and Cellulose in my attic as an upgrade to my 1.5 storey 2008 home.

    Can you expand on this please?



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    #8
    Madd002
    Registered Users Posts: 310 ✭✭Madd002


    we have a bungalow but done upstairs when building so only have crawl space around perimeter. We had a cubby hole in one bedroom but had to cut another one on landing so they could get in and around easily. Had spray foam done 3 yrs ago best thing we ever did. Eg roof this morning was still frozen no heat loss spots which we had before & all the loose insulation taken from rafters we pushed into floor rafters. I remember seeing a programme on uk channel ot long after we got ours done, about a couple who had it done but when they came to sell house young couple couldn't get a mortgage on it and older couple had to pay 8k to get it removed. I rang company we used and they said no ours is breathable we took a sample out since no damp and air is cold in attic but spray foam acts like a wooly hat. We also got a 10yr guarantee. A few local new builds got it also.



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    #9
    jasgrif11
    Registered Users Posts: 434 ✭✭jasgrif11


    https://www.boards.ie/discussion/comment/121589013#Comment_121589013

    My home is a storey and a half, so I have sloped ceilings in some of my bedrooms. The insulation in the slope part is 100mm of rigid Kingspan board. I had a thermal survey done recently, and let's say when the board was fitted, it wasn't fitted very well, which resulted in a lot of gaps for air to flow. I can't easily get to the insulation to remove/fix it without taking the first 6 rows of slates of the house and removing them from the outside, or alternatively, I could dryline the rooms internally.

    If I was to go the route of removing the slates I need to factor in the cost for hiring scaffolding, a roofer to remove the slates and put them back afterwards. I was wondering should I spray foam between the rafters (from the outside) on just the sloped area up as far as the flat ceiling. The foam would go directly onto the back of the plasterboard and I'd leave a 50mm airgap to to the top of the rafter.

    Cellulose would be for the flat part of the ceiling or I could use more rolled insulation.

    Does this make sense?



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    #10
    Biker1
    Registered Users Posts: 387 ✭✭Biker1


    If possible dryline the sloped sections. Removing the slates and using spray foam will make very little difference to what is already there and cost a fortune.



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