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Spray foam insulation cost

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  • 13-07-2010 1:49pm
    #1
    sky.boy
    Registered Users Posts: 47 ✭


    How much does spray foam insulation cost. We are building a 2900sqft timber frame house. Any rough estimates would be very helpful


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    #2
    soldsold
    Registered Users Posts: 552 ✭✭✭soldsold


    It all depends - are you including the cost of replacing rotting roof timbers down the line from the possible condensation issues spray foam might give you?

    :rolleyes:


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    #3
    ei.sdraob
    Closed Accounts Posts: 9,376 ✭✭✭ei.sdraob


    about 4K, how big is the roof?

    @soldsold there are new foam materials now which are open-cell and deal with this issue


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    #4
    beyondpassive
    Registered Users Posts: 558 ✭✭✭beyondpassive


    ei.sdraob wrote: »
    there are new foam materials now which are open-cell and deal with this issue

    I find that the spray foams are no better insulating than mineral wool and no better airtighness than vapour control layers or OSB airtight taped liners. Its not completely foolproof and you do get voids. There are applications which are suited to such a product, but by I would use softboard as the sarking layer, and OSB or intello as VCL/airtight layer when using spray foam anyway, however the cost would push the spec back towards cellulose. So I really can't see an application for spray foam on its own.

    notes
    1. Is a vapour barrier required with open cell, is this to be located fully to the warm side or do i need a 1/3rd insulation inside the vapour barrier to stop it becoming the dew point.
    2. What is the Water vapour diffusion resistance factor (µ) or Vapour resistivity r (MNsg–1)? I have figures for resitivity and resistance for Spray Icynene of 13.15 MN.s/g.m, µ (mu)-value 2.63. This is good but I can't reference the test method or if it is independent.
    3 What is the Thermal resistivity (mKW–1). 0.039W/m.K? once blown, what is the 25 year average 0.049? This is a problem if considering for passive House.


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    #5
    sky.boy
    Registered Users Posts: 47 ✭sky.boy


    It's a bungalow so the roof is big alright. It's 26 metre's in length. We are going to spray foam al the internal walls also. I was thinking about 10k for the whole house. What do you think?


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