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ICF / Insulated Concrete Forms & Passive House

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    #2
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,139 Mod ✭✭✭✭BryanF


    mod note:comments on specific companies by PM

    Manufac16 built an ICF self build ask him.

    Personally I don't get it. We should be minimising the use of concrete. Details in an iCf are only as good as the architect/ arch tech on the job and Irish people going for ICf tend to see it as a self build solution and rarely do enough design drawings prior to commencement.


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    #3
    Anthropology
    Registered Users Posts: 70 ✭✭Anthropology


    That is a good point @BryanF, the theoretical simplicity of it I think is the draw provided you get it designed right and have a Engineering/Implementation team that is on your side when accomplishing it.


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    #4
    CaraK
    Registered Users Posts: 69 ✭✭CaraK


    For passive house the exterior insulation needs to be increased

    I visited a new ICF build recently and when I touched the interior insulation it was wet to the touch, This was the north wall and on the ground floor, the weather had being cold for a few weeks prior to visit,the concrete was poured in September. The house wasn't completed or fully sealed yet. No air tightness was in place and owner wasn't building passive and did not seem one bit concerned or focusssed on cold bridges so didn't gain any insight into this from visit.

    The dampness on the north wall did make me wonder whether the concerns about interstitial condensation being adequately addressed by the ICF providers? In fairness the other walls did not feel damp

    Would love to see how thermal bridges at floor junctions and eaves are detailed.

    The window and door opens are boxed out with plywood or treated timber


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    #5
    Anthropology
    Registered Users Posts: 70 ✭✭Anthropology


    It appears that the ICF walls are just placed and poured onto a concrete slab foundation. I would think there should be a means to connect the two masses to eliminate cold bridging and facilitating air tightness.

    Was the North wall of the ICF build visited already rendered etc @CaraK?


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    #6
    Calahonda52
    Registered Users Posts: 12,364 ✭✭✭✭Calahonda52


    Anthropology wrote: »
    ..
    My outstanding questions are:
    1: How does airtightness happen around windows and doors?
    2: How does thermal bridging get addressed with the foundation to wall?

    URL="http://www.boards.ie/vbulletin/showthread.php?t=2055956172"]older post[/URL

    RE 1: How does ICF differs from say a normal cavity wall for Air tightness. [A/T ]
    As carak has said the opes are shuttered with timber before the concrete gets poured and is usually left in place for getting a fixing so I don't see how A/T is an issue.
    Re 2: Whats the problem here? Any I have seen have used an insulated foundation so if you sketch it out, where is is the T/B?

    “I can’t pay my staff or mortgage with instagram likes”.



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    #7
    CaraK
    Registered Users Posts: 69 ✭✭CaraK


    Anthropology wrote: »
    It appears that the ICF walls are just placed and poured onto a concrete slab foundation. I would think there should be a means to connect the two masses to eliminate cold bridging and facilitating air tightness.

    Was the North wall of the ICF build visited already rendered etc @CaraK?

    One part was rendered and the North West corner was left exposed as the owner had retrieved a whole pile of limestone from the excavation phase which he had sandblasted and was waiting for the stone mason to do his magic


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    #8
    Calahonda52
    Registered Users Posts: 12,364 ✭✭✭✭Calahonda52


    Anthropology wrote: »
    It appears that the ICF walls are just placed and poured onto a concrete slab foundation. I would think there should be a means to connect the two masses to eliminate cold bridging and facilitating air tightness.
    What are you getting at here?
    Can you draw a sketch and post it up showing where the TB is and how it is different from a normal cavity wall?

    Concret is airtight.

    “I can’t pay my staff or mortgage with instagram likes”.



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    #9
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,139 Mod ✭✭✭✭BryanF


    Calahonda52 wrote: »
    What are you getting at here?
    Can you draw a sketch and post it up showing where the TB is and how it is different from a normal cavity wall?

    Concret is airtight.

    Was the floor screed in?


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    #10
    CaraK
    Registered Users Posts: 69 ✭✭CaraK


    BryanF wrote: »
    Was the floor screed in?

    The floors had not being poured on the north section section

    If this refers to the ICF I visited


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    #11
    CaraK
    Registered Users Posts: 69 ✭✭CaraK


    10y19h

    Found this foundation detail to counter potential thermal bridge if a traditional footing is in place

    Every 3 foot epoxy coated rebar is drilled and then the insulation is placed/wedged in between the ICF forms. Insulation needs to be EPS with high PSI . All the pressure will be on the rebar

    https://goo.gl/images/10y19h


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    #12
    Anthropology
    Registered Users Posts: 70 ✭✭Anthropology


    @Calahonda52. If the foundations are set and you begin ICF you'll be pouring wet new concrete onto set dry concrete, isn't there a chance the outside to inside would not be airtight at this junction?

    This would also mean there is a thermal bridge between set concrete and new ICF wall concrete (is only doesn't matter if the bridge is within the building envelope) @CaraK good find shows how to handle this if the foundation is not 'passive' spec.

    I am still not sure how this is covered with Windows and Doors. I have seem people doing the following
    "removing the timber linings which were used to create the window and doors openings to expose the concrete then using tape and membrane to provide airtight seal between the windows and the concrete" - URL here

    When you pour the concrete around the Window and Door settings its concrete on wood, over time the bond would surely breakdown between concrete and wood. Leaving the building ever so slightly not airtight


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    #13
    CaraK
    Registered Users Posts: 69 ✭✭CaraK


    Anthropology wrote: »
    @Calahonda52. If the foundations are set and you begin ICF you'll be pouring wet new concrete onto set dry concrete, isn't there a chance the outside to inside would not be airtight at this junction?

    This would also mean there is a thermal bridge between set concrete and new ICF wall concrete (is only doesn't matter if the bridge is within the building envelope) @CaraK good find shows how to handle this if the foundation is not 'passive' spec.

    I am still not sure how this is covered with Windows and Doors. I have seem people doing the following
    "removing the timber linings which were used to create the window and doors openings to expose the concrete then using tape and membrane to provide airtight seal between the windows and the concrete" - URL here

    When you pour the concrete around the Window and Door settings its concrete on wood, over time the bond would surely breakdown between concrete and wood. Leaving the building ever so slightly not airtight

    The timber will be screwed /bolted/nailed into the concrete through the ICF blocks so won't go anywhere when concrete sets.

    Found this site uses quad lock

    pdf


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    #14
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,139 Mod ✭✭✭✭BryanF


    CaraK wrote: »
    The timber will be screwed /bolted/nailed into the concrete through the ICF blocks so won't go anywhere when concrete sets.

    Found this site uses quad lock

    pdf

    Mod note, please see forum charter, re naming companies

    Hi I've removed a link before one of the regular posters comes on slating the worst 'passive' window cill detail I've ever seen.


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    #15
    Poor Uncle Tom
    Registered Users Posts: 14,547 ✭✭✭✭Poor Uncle Tom


    If you know you are going to be building ICF then why not start with the foundations and not the rising walls?

    Am I right in thinking this 'problem' joint in the concrete shown is approx 700mm below FGFL?


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    #16
    CaraK
    Registered Users Posts: 69 ✭✭CaraK


    Apologies, it is their standard cill detail. A passive one would need more insulation and for the frame to be set in the insulation

    I was hoping they would see it and comment that way everyone could learn from it by recognising what was wrong and to be on the lookout for it on their own build


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    #17
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,139 Mod ✭✭✭✭BryanF


    CaraK wrote: »
    Apologies, it is their standard cill detail. A passive one would need more insulation and for the frame to be set in the insulation

    I was hoping they would see it and comment that way everyone could learn from it by recognising what was wrong and to be on the lookout for it on their own build

    Please familiarise yourself with forum charter thanks


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