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Pumped Cavity versus Xtratherm rigid Insulation

  • 15-04-2015 02:53PM
    #1
    Fuseman
    Banned (with Prison Access) Posts: 158 ✭✭


    Hi Folks

    There is so much information around I am a little overwhelmed and need some guidance.

    We are in the process of just starting an extension for an existing dwelling. The architect spec'd out a 300mm Cavity Wall for the extension. So that would be 100mm Brick, 100mm Insulation and 100mm Brick

    Chatting to the builder today, he said that if he was building the extension for his own house he would pump the cavity and then put up a 50mm Insulated plasterboard inside.

    I am lost :-(

    FM


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Comments

  • #2
    893bet
    Registered Users, Registered Users 2 Posts: 9,745 ✭✭✭893bet


    Fuseman wrote: »
    Hi Folks

    There is so much information around I am a little overwhelmed and need some guidance.

    We are in the process of just starting an extension for an existing dwelling. The architect spec'd out a 300mm Cavity Wall for the extension. So that would be 100mm Brick, 100mm Insulation and 100mm Brick

    Chatting to the builder today, he said that if he was building the extension for his own house he would pump the cavity and then put up a 50mm Insulated plasterboard inside.

    I am lost :-(

    FM
    Ignore both and ask for a 150mm cavity and pump it.


  • #3
    Strolling Bones
    Registered Users, Registered Users 2 Posts: 615 ✭✭✭Strolling Bones


    893bet wrote: »
    Ignore both and ask for a 150mm cavity and pump it.

    +1


  • #4
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,146 Mod ✭✭✭✭BryanF


    893bet wrote: »
    Ignore both and ask for a 150mm cavity and pump it.

    Seconded

    Plastered block internal finish with an eye on air-tightness, your designer should be specifying air-tightness measures


  • #5
    DOCARCH
    Moderators, Home & Garden Moderators, Science, Health & Environment Moderators Posts: 18,905 Mod ✭✭✭✭DOCARCH


    @Fuseman. For balance, there is nothing wrong with what your architect has specified (for an extension to an existing house).

    Full fill cavity insulation is tricky to install correctly, so, I would suggest the builder may (or may not) have a reason for offering his thoughts?

    Personally, if it is brick outer leaf, I would prefer to use (a certified) full fill cavity insulation over bead (not matter what the bead is certified for).


  • #6
    Fuseman
    Banned (with Prison Access) Posts: 158 ✭✭Fuseman


    DOCARCH wrote: »
    @Fuseman. For balance, there is nothing wrong with what your architect has specified (for an extension to an existing house).

    Full fill cavity insulation is tricky to install correctly, so, I would suggest the builder may (or may not) have a reason for offering his thoughts?

    Personally, if it is brick outer leaf, I would prefer to use (a certified) full fill cavity insulation over bead (not matter what the bead is certified for).
    Its not a brick outer leaf. Its just a standard 4" block as far as I am aware. The builder wouldnt do it himself. He would sub contract in a certified insulation company to do the pumping


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  • #7
    Strolling Bones
    Registered Users, Registered Users 2 Posts: 615 ✭✭✭Strolling Bones


    DOCARCH wrote: »
    @Fuseman. For balance, there is nothing wrong with what your architect has specified (for an extension to an existing house).

    Actually - if the existing house is drylined then it would make sense to dry line the extension too.


  • #8
    DOCARCH
    Moderators, Home & Garden Moderators, Science, Health & Environment Moderators Posts: 18,905 Mod ✭✭✭✭DOCARCH


    Fuseman wrote: »
    Its not a brick outer leaf. Its just a standard 4" block as far as I am aware. The builder wouldnt do it himself. He would sub contract in a certified insulation company to do the pumping

    Fair enough. I would not fill a 100mm cavity with bead and dry-line.

    Just to say, your architect will not be too happy if you go back, at this point, and suggest a 150mm cavity and/or 100mm with bead plus dry-lining (as suggested by your builder) as it will change the overall wall thickness (add approx. 50mm to the wall thickness). That could have a knock-on in relation to structure, general detailing and/or space internally.


  • #9
    Fuseman
    Banned (with Prison Access) Posts: 158 ✭✭Fuseman


    DOCARCH wrote: »
    Fair enough. I would not fill a 100mm cavity with bead and dry-line.

    Just to say, your architect will not be too happy if you go back, at this point, and suggest a 150mm cavity and/or 100mm with bead plus dry-lining (as suggested by your builder) as it will change the overall wall thickness (add approx. 50mm to the wall thickness). That could have a knock-on in relation to structure, general detailing and/or space internally.

    Is there specific reason for not filling the cavity with bead and dryline?
    example Mould problems etc


  • #10
    thatslife
    Registered Users, Registered Users 2 Posts: 75 ✭✭thatslife


    I'm currently looking into this same thing.
    I was told to avoid bead. He was explained to me that overtime bead will degrade in the cavity.
    Like a football, air inside beads would slowly seep out and ur insulation thickness wud become less and less


  • #11
    DOCARCH
    Moderators, Home & Garden Moderators, Science, Health & Environment Moderators Posts: 18,905 Mod ✭✭✭✭DOCARCH


    Fuseman wrote: »
    Is there specific reason for not filling the cavity with bead and dryline?
    example Mould problems etc

    Always try and keep your insulation in one layer...if at all possible.


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  • #12
    hexosan
    Registered Users, Registered Users 2 Posts: 1,740 ✭✭✭hexosan


    thatslife wrote: »
    I'm currently looking into this same thing.
    I was told to avoid bead. He was explained to me that overtime bead will degrade in the cavity.
    Like a football, air inside beads would slowly seep out and ur insulation thickness wud become less and less


    Told by who ?? Timmy in the pub or Johnny down the road


  • #13
    thatslife
    Registered Users, Registered Users 2 Posts: 75 ✭✭thatslife


    hexosan wrote: »
    Told by who ?? Timmy in the pub or Johnny down the road

    Johnny told me on the road to the pub and Timmy seconded it. Whats your opinion Hex?


  • #14
    mikeymouse
    Closed Accounts Posts: 568 ✭✭✭mikeymouse


    In same boat here,
    what's the price diff?


  • #15
    sydthebeat
    Subscribers Posts: 42,945 ✭✭✭✭sydthebeat


    thatslife wrote: »
    I'm currently looking into this same thing.
    I was told to avoid bead. He was explained to me that overtime bead will degrade in the cavity.
    Like a football, air inside beads would slowly seep out and ur insulation thickness wud become less and less

    in my opinion, thats rubbish

    polystyrene is already air blown so so teh air has no need to go anywhere
    also its a pretty rigid material... polystyrene boards havent sagged so why would beads?


    quilted material, yes definitely.

    who told you? a foam insulation seller by any chance?


  • #16
    Strolling Bones
    Registered Users, Registered Users 2 Posts: 615 ✭✭✭Strolling Bones


    thatslife wrote: »
    I'm currently looking into this same thing.
    I was told to avoid bead. He was explained to me that overtime bead will degrade in the cavity.
    Like a football, air inside beads would slowly seep out and ur insulation thickness wud become less and less

    Well nothing lasts forever. All materails degrade over time. In this case - centuries.....


  • #17
    thatslife
    Registered Users, Registered Users 2 Posts: 75 ✭✭thatslife


    Relax lads, I'm just repeating what was explained to me. My engineer recommends a 150mm cavity therm. No dry-line. Thoughts? here is the link to it http://www.xtratherm.com/wp-content/uploads/2012/01/CavityTherm2011irl.pdf


  • #18
    Superdaddy
    Registered Users, Registered Users 2 Posts: 234 ✭✭Superdaddy


    thatslife wrote: »
    Relax lads, I'm just repeating what was explained to me. My engineer recommends a 150mm cavity therm. No dry-line. Thoughts? here is the link to it http://www.xtratherm.com/wp-content/uploads/2012/01/CavityTherm2011irl.pdf

    Ive used it in mine. Major hassle with getting blocklayers to install it as per instructions. Great product when installed correctly in my opinion.


  • #19
    thatslife
    Registered Users, Registered Users 2 Posts: 75 ✭✭thatslife


    Superdaddy wrote: »
    Ive used it in mine. Major hassle with getting blocklayers to install it as per instructions. Great product when installed correctly in my opinion.

    Any tips on installation?


  • #20
    soccercrew
    Registered Users, Registered Users 2 Posts: 116 ✭✭soccercrew


    thatslife wrote: »
    I'm currently looking into this same thing.
    I was told to avoid bead. He was explained to me that overtime bead will degrade in the cavity.
    Like a football, air inside beads would slowly seep out and ur insulation thickness wud become less and less

    I have opened up 25 yr old walls with beads and no change whatsoever.


  • #21
    Superdaddy
    Registered Users, Registered Users 2 Posts: 234 ✭✭Superdaddy


    thatslife wrote: »
    Any tips on installation?

    Get a Blocklayer that's happy to build from the outside on scaffold. If they don't follow instructions, sack them without hesitation.


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  • #22
    murphy31ie
    Registered Users, Registered Users 2 Posts: 62 ✭✭murphy31ie


    Hi,
    Currently in the process of a self build, starting the roof next week. I have a 150 mm cavity that I am going to pump, did not want to build in insulation as you need to be standing over the builders to ensure joints are being taped. Anyway was planning on dry lining along with the 150 mill pumped cavity, is that a bad idea. Cheers for any info


  • #23
    murphy31ie
    Registered Users, Registered Users 2 Posts: 62 ✭✭murphy31ie


    murphy31ie wrote: »
    Hi,
    Currently in the process of a self build, starting the roof next week. I have a 150 mm cavity that I am going to pump, did not want to build in insulation as you need to be standing over the builders to ensure joints are being taped. Anyway was planning on dry lining along with the 150 mill pumped cavity, is that a bad idea. Cheers for any info

    Sorry I should have added it is 50mm dry lining.


  • #24
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,146 Mod ✭✭✭✭BryanF


    murphy31ie wrote: »
    Hi,
    Currently in the process of a self build, starting the roof next week. I have a 150 mm cavity that I am going to pump, did not want to build in insulation as you need to be standing over the builders to ensure joints are being taped. Anyway was planning on dry lining along with the 150 mill pumped cavity, is that a bad idea. Cheers for any info

    This is debated to death here, try typing variations of key words into the advanced search.

    insulation is best kept in the cavity. Why dry line? You lose the thermal mass of the Blockwork and potentially air-tightness. What is your expected air-tightness figure stated in the building contract?


  • #25
    murphy31ie
    Registered Users, Registered Users 2 Posts: 62 ✭✭murphy31ie


    BryanF wrote: »
    This is debated to death here, try typing variations of key words into the advanced search.

    insulation is best kept in the cavity. Why dry line? You lose the thermal mass of the Blockwork and potentially air-tightness. What is your expected air-tightness figure stated in the building contract?

    We were advised by the BER man to dry line, my dad is looking after the job as he is a retired contractor but from him there will be a scratch coat and the boards will be mechanically fixed. I would need to look up the expected air tightness figure, we are trying for as air tight as we can. Thanks for any info again


  • #26
    _Brian
    Registered Users, Registered Users 2 Posts: 18,962 ✭✭✭✭_Brian


    When we built our main house 8 years ago we pumped the 100 mm cavity and put 50mm board on the inside.

    Our cavity is pumped with certified bead. In the loft space where I can access the top Of the cavity the head is still rigid and in place. This is near 3 stories up and there is no evidence if sag. The bead still feels rigid as the week it was done.

    Rigid insulation in cavities is easy to fit but difficult to fit properly and detail so as to prevent air ingress, and many are so poorly detailed around corners and windows to render them useless.


  • #27
    murphy31ie
    Registered Users, Registered Users 2 Posts: 62 ✭✭murphy31ie


    _Brian wrote: »
    When we built our main house 8 years ago we pumped the 100 mm cavity and put 50mm board on the inside.

    Our cavity is pumped with certified bead. In the loft space where I can access the top Of the cavity the head is still rigid and in place. This is near 3 stories up and there is no evidence if sag. The bead still feels rigid as the week it was done.

    Rigid insulation in cavities is easy to fit but difficult to fit properly and detail so as to prevent air ingress, and many are so poorly detailed around corners and windows to render them useless.

    Hi Brian

    Are you happy you went with the dry lining?


  • #28
    eoinvden
    Registered Users, Registered Users 2 Posts: 6 ✭eoinvden


    Just wondering if anyone has any experience of using xtratherm cavity fill rigid board insulation. We're considering it for a new build but its very expensive.The architect had originally specified it for 150mm cavity but is now suggesting we could use Quinn 110mm insulation which would give u values close to but not quiet as good as xtratherm. There is a significant price difference (almost double). Any help would be appreciated


  • #29
    sydthebeat
    Subscribers Posts: 42,945 ✭✭✭✭sydthebeat


    Have you had your preliminary DEAP assessment done to find out what spec you need to comply with regs?

    Exactly what product AND thickness did the architect specify.
    And exactly what product AND thickness are you considering as an alternative


  • #30
    The R Tech
    Registered Users, Registered Users 2 Posts: 2 ✭The R Tech


    What do people think about, the level of workmanship deteriorating when block layers don't have to deal with insulation in the cavity. Such defects as mortar dropping down to the DPC, un-scrapped joints etc. In addition for pumped insulation the deap software requires thermal imaging to ensure there are no air pockets in the corners etc. to use the y-Value.
    Any thoughts guys


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  • #31
    DOCARCH
    Moderators, Home & Garden Moderators, Science, Health & Environment Moderators Posts: 18,905 Mod ✭✭✭✭DOCARCH


    Mod Note: Decided to merge two threads on same/similar topic.


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