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Spray foam insulation

  • 24-11-2020 8:19pm
    #1
    Registered Users Posts: 7,260 ✭✭✭ tom1ie


    Hi all
    I’m thinking of getting spray foam insulation done in the attic.
    I already have about 2 rolls thick (400mm?) of earth wool insulation in the attic.
    Is it worth getting the rafters sprayed also?
    Does the spray go all the way to the wall plate and block off the ventilation to the roof?
    I have installed 50mm insulated plasterboard on all the external walls, would it be worth getting the walls pumped with spray foam also?

    It’s a 1966 semi detached brick built 4 bed.

    Thanks all.


Comments

  • Registered Users Posts: 2,544 ✭✭✭ MicktheMan


    tom1ie wrote: »
    Is it worth getting the rafters sprayed also?

    No. The insulation on the attic floor defines your thermal envelope and the rafters are outside this so no impact.


  • Registered Users Posts: 7,260 ✭✭✭ tom1ie


    MicktheMan wrote: »
    No. The insulation on the attic floor defines your thermal envelope and the rafters are outside this so no impact.

    Grand. So if I wanted to improve heat retention in the house I would increase the depth of this insulation.

    What’s your view on getting the cavity’s in the external walls sprayed even though I have the inside slabbed? Is this outside the thermal envelope also?
    Thanks.


  • Registered Users Posts: 252 ✭✭ Biker1


    Cavity could be pumped provided it is not in one of the defined hi exposure areas.


  • Registered Users Posts: 7,260 ✭✭✭ tom1ie


    Biker1 wrote: »
    Cavity could be pumped provided it is not in one of the defined hi exposure areas.

    Right.
    Sorry, I don’t know what they would be? Would you have a link or anything please?


  • Registered Users Posts: 2,544 ✭✭✭ MicktheMan


    tom1ie wrote: »
    Grand.
    1. So if I wanted to improve heat retention in the house I would increase the depth of this insulation.

    2. What’s your view on getting the cavity’s in the external walls sprayed even though I have the inside slabbed? Is this outside the thermal envelope also?
    Thanks.

    1. No, not necessarily. What's your air tightness like?
    2. Is it certified for this application? No certification, no dice.


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  • Registered Users Posts: 7,260 ✭✭✭ tom1ie


    MicktheMan wrote: »
    1. No, not necessarily. What's your air tightness like?
    2. Is it certified for this application? No certification, no dice.

    I would say the air tightness would be poor enough to be honest. We have new windows new front and back door all external walls slabbed and insulated plasterboard brought to edge of windows to eliminate cold bridging, but, attic insulation is ok, doesn’t go all the way to the soffit to allow air in and let rafters breathe.
    Floating laminated floors over wooden floorboards which are over vented base wall footings so there’s no air tightness there.

    I presume it’s a massive deep retrofit type job to get a building like mine air tight?


  • Registered Users Posts: 2,544 ✭✭✭ MicktheMan


    tom1ie wrote: »

    I presume it’s a massive deep retrofit type job to get a building like mine air tight?

    Depends really but not necessarily once you know (or have been shown) where for example the top 3 issues are. If 2 of these can be easily addressed and the 3rd maybe later when improving something else then real improvements are possible without breaking the bank. There is generally also more than one way to airtighten a building and measures can always be incorporated when doing other works / improvements.


  • Registered Users Posts: 30,657 ✭✭✭✭ listermint


    MicktheMan wrote: »
    No. The insulation on the attic floor defines your thermal envelope and the rafters are outside this so no impact.

    Tbf though, moving the ventilation into the rafter space via approved card system and baffles . And then turning the attic space into a warm room does have an impact on the thermal envelope of the house.

    Saying it has no impact isn't true.


  • Registered Users Posts: 2,544 ✭✭✭ MicktheMan


    listermint wrote: »
    Tbf though, moving the ventilation into the rafter space via approved card system and baffles . And then turning the attic space into a warm room does have an impact on the thermal envelope of the house.

    Saying it has no impact isn't true.

    I was describing the impact within the existing thermal envelope i.e. the room(s) below the insulated attic floor. No mention was made by the OP of turning the attic into a habitable space which I think you are proposing if I understand your post correctly.

    Also, there is a myth out there that sprayfoam deals with airtightness as well as insulation and many '000s of euro have been spent in error by homeowners in these types of situations thinking they will have a warm attic by sprayfoaming the rafters.


  • Registered Users Posts: 7,260 ✭✭✭ tom1ie


    MicktheMan wrote: »
    I was describing the impact within the existing thermal envelope i.e. the room(s) below the insulated attic floor. No mention was made by the OP of turning the attic into a habitable space which I think you are proposing if I understand your post correctly.

    Also, there is a myth out there that sprayfoam deals with airtightness as well as insulation and many '000s of euro have been spent in error by homeowners in these types of situations thinking they will have a warm attic by sprayfoaming the rafters.

    Tbf I would have thought this was the case!!


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  • Registered Users Posts: 252 ✭✭ Biker1


    MicktheMan wrote: »
    I was describing the impact within the existing thermal envelope i.e. the room(s) below the insulated attic floor. No mention was made by the OP of turning the attic into a habitable space which I think you are proposing if I understand your post correctly.

    Also, there is a myth out there that sprayfoam deals with airtightness as well as insulation and many '000s of euro have been spent in error by homeowners in these types of situations thinking they will have a warm attic by sprayfoaming the rafters.

    So true


  • Registered Users Posts: 11 Cass007


    MicktheMan wrote: »
    I was describing the impact within the existing thermal envelope i.e. the room(s) below the insulated attic floor. No mention was made by the OP of turning the attic into a habitable space which I think you are proposing if I understand your post correctly.

    Also, there is a myth out there that sprayfoam deals with airtightness as well as insulation and many '000s of euro have been spent in error by homeowners in these types of situations thinking they will have a warm attic by sprayfoaming the rafters.

    Hi Mick,

    How is a warm attic obtained? Do you mean a sprayfoam insulation won't give you this? If someone was turning an attic into a habitable space what is the recommended way to do this regarding insulation?


  • Registered Users Posts: 195 ✭✭ In the wind


    tom1ie wrote: »
    Hi all
    I’m thinking of getting spray foam insulation done in the attic.
    I already have about 2 rolls thick (400mm?) of earth wool insulation in the attic.
    Is it worth getting the rafters sprayed also?
    Does the spray go all the way to the wall plate and block off the ventilation to the roof?
    I have installed 50mm insulated plasterboard on all the external walls, would it be worth getting the walls pumped with spray foam also?

    It’s a 1966 semi detached brick built 4 bed.

    Thanks all.

    I'm in a similar situation. Our upstairs rooms adjoin the unoccupied attic (dormer), those room are alway much colder even with heat on. I was considering replacing all the fibreglass insulation on the dwarf walls with kingspan fitted between the studs. Not a small or cheap job but yesterday i received my FLIR One thermal imaging camera & surveyed the rooms upstairs & basically the dwarf wall is quite well insulated with a few cold spots that need to be remedied.

    The major heat sink was the sloping section from the top of the dwarf wall to the dormer ceiling. This was measuring 5.5'C last night when I checked. That sloping section runs the whole length of the upstairs on both sides about 30sqm of heat sink. It's difficult to access this section which might explain why there is only expanded polystyrene (aeroboard:rolleyes:) for the first 30cm on the lower side.
    Check out the picture.

    So now i got to spray foam this section & i'm in the market for a competitive professional vendor with all the required certificates - any recommendations appreciated.


  • Registered Users Posts: 195 ✭✭ In the wind


    So I have the sprayer in today. The carding is being completed right now on the last area while the spraying is ongoing in another area.

    The last area being carded is being handled differently for some reason & I need urgent expert advice before they start spraying.

    The carding in the last area is being stapled underneath the joist & not between them. It is laid flat across the bottom of the joists & is not being fitted between them in a U shape as has been done in other areas.

    The building reg writes about insulation "BETWEEN" & "UNDERNEATH" the joists but the carding is being set up to go just underneath leaving the full depth of the joists uninsulated.

    Any expert advice greatly appreciated.

    https://thebuildingregulations.ie/guides/TGD_L__Buildings_other_than_Dwellings/Appendix_B_Fabric_Insulation_Additional_Guidance_including_Tables_of_U_values_for_Common_Constructions/Roof_constructions/


  • Registered Users Posts: 1,247 ✭✭✭ dathi


    the quickest answer is to ask them perhaps there are cables in the area ?


  • Registered Users Posts: 195 ✭✭ In the wind


    I just challenged it & he said he done it that way because it was faster.
    I rejected that as a good reason because I don't care about fast, I care about correct.
    He then changed tack & said the space was too tight.
    I challenged that with the fact that a different space they just completed correctly was even tighter.
    He then acknowledged that they were shortcutting & would rework the whole lot correctly.

    In a sense they should be thankful that I spotted this before they had started to spray as the rework could have been a lot more.
    The boss just turned up coincidentally & I brought it to his attention & he said it was completely wrong & that they had to rework the whole lot.

    It pays to keep an eye on workers & quality of work & understand the standards. I hope this is helpful to others in future.


  • Registered Users Posts: 195 ✭✭ In the wind


    dathi wrote: »
    the quickest answer is to ask them perhaps there are cables in the area ?

    Thanks Dathi, no mention of cables or any other good reason other than its faster. Sigh.


  • Registered Users Posts: 2,544 ✭✭✭ MicktheMan


    Cass007 wrote: »
    Hi Mick,

    How is a warm attic obtained? Do you mean a sprayfoam insulation won't give you this? If someone was turning an attic into a habitable space what is the recommended way to do this regarding insulation?

    Apologies, only seeing this Q now.
    Addressing heat loss in turning any space including an attic into a conditioned space requires, in the main, 2 things; insulation AND air tightness. Sprayfoam may well insulate but will not suffice for air tightness (regardless of what the salesman tells you) i.e. you still need to define and implement you air tight barrier. This is the point I am making.


  • Registered Users Posts: 195 ✭✭ In the wind


    I just challenged it & he said he done it that way because it was faster.
    I rejected that as a good reason because I don't care about fast, I care about correct.
    He then changed tack & said the space was too tight.
    I challenged that with the fact that a different space they just completed correctly was even tighter.
    He then acknowledged that they were shortcutting & would rework the whole lot correctly.

    In a sense they should be thankful that I spotted this before they had started to spray as the rework could have been a lot more.
    The boss just turned up coincidentally & I brought it to his attention & he said it was completely wrong & that they had to rework the whole lot.

    It pays to keep an eye on workers & quality of work & understand the standards. I hope this is helpful to others in future.

    so they're just tidying up there now. It makes quite a mess but a cleanable mess.

    -I completed a full inspection & found about a dozen spots of poor coverage / no coverage & they went in and fixed it up.

    -Fibreglass insulation needs to be rolled back into place where it was pushed aside for access.

    -Excess carding material needs to be removed from the attic as it is a fire hazard & looks like crap.

    - several monster cans cleaned up - it is hot stuffy work - I don't envy they guys but they were masked up.

    - the hardened foams crumbs & dust are all over the place but they're vacuuming that up now.

    -Plenty of wall & door scrapes from working in the area, I'll assess that when the place is cleared out. A little care here would have prevented this.

    - I noticed a chimney stack that is not sprayed is already sweating in the attic space so that needs to be dealt with intelligently. Sigh.


    Now lets see how the house feels tonight...


  • Registered Users Posts: 197 ✭✭ social butterfly 2020




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  • Registered Users Posts: 195 ✭✭ In the wind


    Yep I'm pleased with the result. The job seems to be working well & the house is warmer & quieter for sure. You will need to monitor the work as it proceeds & I recommend holding back 10% payment for a month or so until you have had time to complete inspection & to allow time for you to find issues or damage.

    I do need to throw an eye on the chimney that was sweating , in fact I'll do it this evening.



  • Registered Users Posts: 585 ✭✭✭ C. Eastwood


    tom1ie. I recommend that you should not expose your family to spray foam. See court case here:- https://www.irishtimes.com/news/crime-and-law/courts/high-court/judge-awards-couple-2m-in-damages-over-spray-foam-insulation-exposure-1.4427991?mode=sample&auth-failed=1&pw-origin=https%3A%2F%2Fwww.irishtimes.com%2Fnews%2Fcrime-and-law%2Fcourts%2Fhigh-court%2Fjudge-awards-couple-2m-in-damages-over-spray-foam-insulation-exposure-1.4427991

    It is best to have plenty of ventilation in the attic and the way to prevent Wet Rot and Dry Rot in timber is to have plenty of fresh air, which will ensure that the roof timbers are at approx 16% moisture content. The fresh air will also reduce/prevent condensation on the underside of the felt.

    External Walls. I can’t remember when Concrete bricks were introduced to Ireland, they were certainly in use in the 70’s. If your outer bricks are Concrete (usually light grey colour and some were dark grey) then you need expert independent advice on filling the cavity with insulation, to avoid ingress of rainwater and rising damp.



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