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ICFs in a Cold Climate

plainsbuilder | Posted in General Questions on

Hello all, I’m working to gain a better understanding of ICF’s and leveraging thermal mass in a Northern climate (N. Dakota 100+ in summer -40 winter so a healthy range)

I’ve always wanted to build a home with ICF’s foundation to top plate for a few reasons, quiet (our land is near a busy road & its windy often here), solid, structure, building a ranch with basement etc.

From my reading the case for ICF’s isn’t as strong up North as it might in desert country down South. We were looking at going with a graphite poly product ICF block and then adding some additional insulation on the exterior (Logix Exterra 2″+2″). I’ve worked with Zola windows in the past and plan to use those as well for quality glazing.

I would greatly apricate any options on how to optimize using ICF’s in climate zone 7 and would welcome any other thoughts!

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  1. this_page_left_blank | | #1

    ICF is just about the least green way to build. Massive amounts of two highly energy intensive materials, concrete and foam. It's also very expensive compared to other wall systems.

    Thermal mass in exterior walls is not a benefit in such a cold climate. In the winter, the average temperature in the mass part of the wall is always going to be well below the desired indoor temperature. So day and night, most of the heat going into the wall will be coming from inside the house. In warmer parts of the year, you'll get some buffering, but's also the time when your HVAC loads will be low anyway.

  2. jackofalltrades777 | | #2

    Nudura offers a X35 form which has a 6" concrete core and 4" of foam on each side.

    So you will get a R-35 wall with no thermal bridging and built to stand 100+ years from now. I've built with ICF and don't regret it at all. Some people on the forum will bring up the point about concrete not being environmentally friendly due to the embodied energy it takes to make it. I guess building wood homes and having them burn down in wildfires and blown to bits in tornadoes, only to have them rebuilt again and again, is considered "green" ?

    A Zone 7 climate in Northern America won't see the full benefits of the thermal mass as an ICF home would see in the desert southwest with diurnal temp swings of 40 degrees per day. Even so, you are still getting a R-35 wall assembly with no to very little thermal bridging, plus the strength and longevity of concrete.

    Space X rocket runs on fossil fuels, namely Rocket Propellant 1 or RP-1, which is highly refined kerosene. Each launch burns 29,600 gallons or 112,184 Kilograms, with each Kg of fuel releasing 3 Kg of CO2, so each launch releases 336,552 Kg of CO2. 118 rocket launches were reported in 2018. Yet, this is never criticized !?!?

    Build your home with ICF. You won't regret it. 100+ years from now, the house will still be standing for future generations to enjoy and use.

    1. this_page_left_blank | | #3

      Space X gets criticised, though not as much as it should. But that is really beside the point. None of us have any influence on what Space X does.

  3. T_Barker | | #4

    I believe ICF's are now used for the majority of rural/remote foundations in Zone 7 in my area. Excellent system for basements. But make sure your contractor has all of the proper bracing and training from the ICF manufacturer.

    Having said that, I wouldn't build any above-grade walls with ICF's. You have to have every single electrical outlet, window, etc., planned to a "T" before you pour. In my opinion, that is very difficult to achieve with any home.

    As far as thermal mass, in my opinion you have to either commit to thermal mass and the long slow swings in temperature, or instead fully insulate everything from exterior temperatures and solar radiation, and let the HVAC system control the internal environment. I'm in the latter camp.

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