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Insulation

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  • 23-07-2014 11:26am
    #1
    alemap83
    Registered Users Posts: 37 ✭


    Hello,

    We are building an 3300sqft house with 150mm cavity wall. Can anyone recommend what insulation we should go with? Here's is some more information on the house.

    - we want a completely airtight house with a heat recovery unit
    - Solid fuel stove to heat the house along with oil also as backup
    - hoping to get a A2/3 rating
    - double glazed uPVC windows

    not sure if you need any more info. As you can probably gather from the above I'm pretty clueless!! We have gotten quotes from a few different builders and all their recommendations are completely different!
    I would appreciate any advice.. Thanks Pam
    Tagged:


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    #2
    Drift
    Closed Accounts Posts: 1,395 ✭✭✭Drift


    Hi Pam,

    Do you have a professional employed to design the house?

    Carrying out a DEAP/BER calculation for the house is essential to make sure it complies with the building regulations. This calculation will have the added benefit of giving you a good idea what the final BER Rating will be when the house is complete. A builder will not be able to do this.

    If you have not yet lodged your commencement notice you will have to submit these calculations before you start building anyway so there's no way to avoid doing them.

    P.S. You'll find when these calculations are done you'll have a much more accurate list of what you need in terms of insulation properties of windows, walls, etc and a target value for airtightness. (There's no such thing as a "completely airtight" house - it's a case of reducing the leakage to a very low level.)


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    #3
    snoop09
    Registered Users Posts: 49 ✭snoop09


    Hi,

    I built a similar house to what you are saying 2 years ago, I have 125mm pumped cavity wall insulation, 37.5mm insulated plasterboard on all external walls, 2 rows of 200mm attic insulation, double glazed future proof windows, air tightness tape around all window, door opes etc...

    I have a solid fuel stove and oil burner,

    Now here is my question, can anybody answer, if not can you recommend what thread I go to,

    My house is like a sauna in the summer, reaches up to 28 deg internally and in winter it is like an ice box, hit lows of 16 degs last winter!

    As winter is fast approaching, can anyone shed any light on my problem as how I can fix it?

    Thanks,

    Snoop


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    #4
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,140 Mod ✭✭✭✭BryanF


    snoop09 wrote: »
    Hi,

    I built a similar house to what you are saying 2 years ago, I have 125mm pumped cavity wall insulation, 37.5mm insulated plasterboard on all external walls, 2 rows of 200mm attic insulation, double glazed future proof windows, air tightness tape around all window, door opes etc...

    I have a solid fuel stove and oil burner,

    Now here is my question, can anybody answer, if not can you recommend what thread I go to,

    My house is like a sauna in the summer, reaches up to 28 deg internally and in winter it is like an ice box, hit lows of 16 degs last winter!

    As winter is fast approaching, can anyone shed any light on my problem as how I can fix it?

    Thanks,

    Snoop
    • thermal bridges
    • lack of air-tightness
    • hole in the wall vents
    • plasterboard on walls means thermal mass is not utilized and building heats up quickly but looses heat just as quickly
    • open flues
    take you pick, there will be other items but this is blind survey:)



    perhaps get a heat loss/air-tightness survey done

    btw don't spam posts across different forums, one post is enough! thanks

    edit: other 'soon to build' posters please refer to snoops post when he was planning to build, note the post 8# :)


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    #5
    sydthebeat
    Subscribers Posts: 41,072 ✭✭✭✭sydthebeat


    the stand out reason there is the internal insulated plasterboard

    youve removed valuable thermal mass which helps regulate your internal temperatures.


  • Options
    #6
    MicktheMan
    Registered Users Posts: 2,825 ✭✭✭MicktheMan


    sydthebeat wrote: »
    the stand out reason there is the internal insulated plasterboard

    youve removed valuable thermal mass which helps regulate your internal temperatures.

    ^^^^that and the block wall behind the insulated plasterboard is probably not air tightened.


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    #7
    DaveWalsh2020
    Registered Users Posts: 34 ✭DaveWalsh2020


    Id say the reason is ......

    Air is infiltrating the thermal dry lining system from the attic sections ( where ceiling plasterboard is fixed to joists and butted into wall it only takes 1 - 2 mm for thermal looping or air infiltration).

    Are the thermally lined boards blobbed on or mushroom fixed ??

    This air can travel from the ceilings into the thermal dry lining and on into the floor joisting and even on into the down stairs thermal lining system and into sockets etc.

    This film of air can render the cavity wall insulation useless as its taking the heat from the back of the 38mm thermal lined plasterboard.

    This thermal board is small and the detail is the best place to stop conduction !!

    Air moves through cavity wall insulation beads which means it can also take heat away ( beads do impede airflow but not stop it) Slow pour spray foam is a better product as it stops moisture and stops air.

    There may be other building fabric details making these weakness s worse , like a suspended timber floor , 4 " vents in all the rooms which are not sealed properly.

    I have seen people go for thermal mass and put in 200mm cavities as they think the heat will conduct into the wall and then hit this big fat layer of beads and bounce back!!! , they dont realise air moves well through the beads and i suspect that the rate at which the air (in the beads) takes heat from the thermal mass is faster than the rate at which it is being conducted through the thermal mass.


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    #8
    galwaytt
    Registered Users Posts: 12,761 ✭✭✭✭galwaytt


    I would think less the issue is the insulated plasterboard, but certainly airtightness would be my favourite suspect.

    I would recommend investing in an airtightness test. Then you'll have something to work from. Or, as they say in TV crime drama, 'to eliminate from our enquiries'.

    Ode To The Motorist

    “And my existence, while grotesque and incomprehensible to you, generates funds to the exchequer. You don't want to acknowledge that as truth because, deep down in places you don't talk about at the Green Party, you want me on that road, you need me on that road. We use words like freedom, enjoyment, sport and community. We use these words as the backbone of a life spent instilling those values in our families and loved ones. You use them as a punch line. I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the tax revenue and the very freedom to spend it that I provide, and then questions the manner in which I provide it. I would rather you just said "thank you" and went on your way. Otherwise I suggest you pick up a bus pass and get the ********* ********* off the road” 



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    #9
    RITwing
    Banned (with Prison Access) Posts: 246 ✭✭RITwing


    Do you have recessed lighting ? During the day i.e. when they are not warm from being switched on see if you can feel cool air entering around them

    I agree with all the points made about insulated plasterboard too.


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    #10
    RITwing
    Banned (with Prison Access) Posts: 246 ✭✭RITwing


    alemap83 wrote: »
    We have gotten quotes from a few different builders and all their recommendations are completely different!
    I would appreciate any advice.. Thanks Pam

    You need to appoint an architect engineer or surveyor to comply with building regs. anyway so ask them - don't find yourself in snoops position later


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    #11
    rampantbunny
    Registered Users Posts: 907 ✭✭✭rampantbunny


    DaveWalsh2020 wrote: »

    I have seen people go for thermal mass and put in 200mm cavities as they think the heat will conduct into the wall and then hit this big fat layer of beads and bounce back!!! , they dont realise air moves well through the beads and i suspect that the rate at which the air (in the beads) takes heat from the thermal mass is faster than the rate at which it is being conducted through the thermal mass.

    OP, don't want to hijack, but something in the above has my attention.

    I've a 200mm cavity wall construction.
    @DaveWalsh2020, are you saying that I will be robbed of heat because I intend to use bead insulation, due to airflow between beads?
    How strong are your suspicions? Evidence based?

    External walls are plastered and opes are sealed. The only place I can see air coming in is at wall plate level and along gables (and possibly service penetrations which will be sealed in any case).
    Should people be looking at sealing at wall plate and other areas with foam and the like, or is the airflow between beads actually negligible.


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    #12
    galwaytt
    Registered Users Posts: 12,761 ✭✭✭✭galwaytt


    DaveWalsh2020 wrote: »
    I have seen people go for thermal mass and put in 200mm cavities as they think the heat will conduct into the wall and then hit this big fat layer of beads and bounce back!!! , they dont realise air moves well through the beads and i suspect that the rate at which the air (in the beads) takes heat from the thermal mass is faster than the rate at which it is being conducted through the thermal mass.

    ...not to mention the fact that if some of your walls are block-on-flat (say to support hollow core as in some houses), you've twice as much mass.....without an internal dry lining, no room is getting warm until you heat the structure first........

    Ode To The Motorist

    “And my existence, while grotesque and incomprehensible to you, generates funds to the exchequer. You don't want to acknowledge that as truth because, deep down in places you don't talk about at the Green Party, you want me on that road, you need me on that road. We use words like freedom, enjoyment, sport and community. We use these words as the backbone of a life spent instilling those values in our families and loved ones. You use them as a punch line. I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the tax revenue and the very freedom to spend it that I provide, and then questions the manner in which I provide it. I would rather you just said "thank you" and went on your way. Otherwise I suggest you pick up a bus pass and get the ********* ********* off the road” 



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    #13
    rampantbunny
    Registered Users Posts: 907 ✭✭✭rampantbunny


    galwaytt wrote: »
    ...not to mention the fact that if some of your walls are block-on-flat (say to support hollow core as in some houses), you've twice as much mass.....without an internal dry lining, no room is getting warm until you heat the structure first........

    Let's say the thermal mass (be it block on edge or flat) is warmed up, do you have an opinion on the loss of heat from airflow through pumped bead insulation?


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    #14
    sydthebeat
    Subscribers Posts: 41,072 ✭✭✭✭sydthebeat


    rampantbunny wrote: »
    Let's say the thermal mass (be it block on edge or flat) is warmed up, do you have an opinion on the loss of heat from airflow through pumped bead insulation?

    if that happens it a sign of incredibly bad workmanship.

    there should be no ventilation opportunities in the cavity (its not a timber frame ;) )

    all external opes should be sealed, all pipe extrusions sealed, all cavities sealed.
    Also, the beads are put in with a glue mix as well which means draughts arent allowed to blow freely through a cavity.

    Thermal mass is widely valued as a good low cost energy efficiency factor.


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    #15
    rampantbunny
    Registered Users Posts: 907 ✭✭✭rampantbunny


    sydthebeat wrote: »
    if that happens it a sign of incredibly bad workmanship.

    there should be no ventilation opportunities in the cavity (its not a timber frame ;) )

    all external opes should be sealed, all pipe extrusions sealed, all cavities sealed.
    Also, the beads are put in with a glue mix as well which means draughts arent allowed to blow freely through a cavity.

    Thermal mass is widely valued as a good low cost energy efficiency factor.

    Very good..thought this was the accepted view, but a previous post made me stop and think.

    "..its not a timber frame"...meow :)


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    #16
    THE DON FANUCCI
    Banned (with Prison Access) Posts: 144 ✭✭THE DON FANUCCI


    Drift wrote: »
    Hi Pam,

    Do you have a professional employed to design the house?

    Carrying out a DEAP/BER calculation for the house is essential to make sure it complies with the building regulations. This calculation will have the added benefit of giving you a good idea what the final BER Rating will be when the house is complete. A builder will not be able to do this.

    If you have not yet lodged your commencement notice you will have to submit these calculations before you start building anyway so there's no way to avoid doing them.

    P.S. You'll find when these calculations are done you'll have a much more accurate list of what you need in terms of insulation properties of windows, walls, etc and a target value for airtightness. (There's no such thing as a "completely airtight" house - it's a case of reducing the leakage to a very low level.)

    how do I carry out a ber/deap calculation??


  • Options
    #17
    rampantbunny
    Registered Users Posts: 907 ✭✭✭rampantbunny


    THE DON FANUCCI wrote: »
    how do I carry out a ber/deap calculation??

    You're a little late to the party TDF, but you should look for a BER Assessor. This is not something you should take on yourself.

    https://ndber.seai.ie/Pass/assessors/search.aspx


  • Options
    #18
    murphy31ie
    Registered Users Posts: 62 ✭✭murphy31ie


    Hi,
    Currently in the middle of a new build, Windows's and doors in now, plan was for a 150mm pumped cavity and 50mm dry lined. I regret now not just having a 200mm cavity. Help really needed, should I not bother with the dry lining and just go with the 150mm pumped cavity??? The plasterboard was going to be mechinally fixed and the block wall was going to be scratch coated.


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    #19
    THE DON FANUCCI
    Banned (with Prison Access) Posts: 144 ✭✭THE DON FANUCCI


    murphy31ie wrote: »
    Hi,
    Currently in the middle of a new build, Windows's and doors in now, plan was for a 150mm pumped cavity and 50mm dry lined. I regret now not just having a 200mm cavity. Help really needed, should I not bother with the dry lining and just go with the 150mm pumped cavity??? The plasterboard was going to be mechinally fixed and the block wall was going to be scratch coated.

    Why do you regret not going with the 200mm pumped cavity? I'm starting new build soon. I need advice!


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    #20
    sydthebeat
    Subscribers Posts: 41,072 ✭✭✭✭sydthebeat


    THE DON FANUCCI wrote: »
    Why do you regret not going with the 200mm pumped cavity? I'm starting new build soon. I need advice!

    what does your assigned certifier advise?


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