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House Build

Insulating Concrete Form

In the design of our home I have ceded almost all territory to Kate. The bedrooms, bathrooms, general living areas, and kitchen are hers to design and rule. I have asked for 3 things: a full basement, a large garage, and a large section of southern facing roof for solar.

Of these 3 things the basement has me the most excited. In the house I grew up in we had a basement and my bedroom was down there. The insulative properties of a basement cannot be overstated. Light, sound, and heat are all better kept in a basement as the walls are concrete and the earth is a massive insulating barrier.

Over the last few years I have worked on a few construction projects. Specifically I have worked on building foundations and crawl spaces. In these projects I was introduced to Insulating Concrete Forms aka ICF. With ICF traditional metal forms are replaced with lighter forms generally made from Styrofoam. These are much easier to construct and after the concrete is poured are left behind to serve as insulation.

Our designer is familiar with ICF and has worked them into our basement design. For a moment we considered doing ICF for the walls of the house as well. We cancelled that idea due to cost and practicality. With ICF you have a concrete wall so remodeling is more difficult. Additionally while ICF does add insulation to the concrete wall it is only an R-17. Our goal is a minimum of R-20 with the walls. I will talk more about the walls in another post.

Now we need to find builders who are familiar with ICF. We don’t want to be someones first time. It seems like a win-win for the builder as ICF requires considerably less skill to install. I am an example of this. Its pretty much like building legos.

As the blocks are installed on top of the foundation reinforced bar (rebar) is added to give tensile strength to the concrete. Then concrete is poured at 4 foot levels to build up the wall while avoiding the dreaded blowout.

A blowout is when part or all of the form fails and concrete pours out. As you can imagine this is a disaster and to be avoided at all costs. Hence the saying of respect: “Concrete waits for no man.

We will have a few windows in the basement but for the most part its gonna be dark and awesome. The main floor of the house will be built with BCI Joists which will be able to span the width of the basement. This will allow us to avoid needing any support walls or posts in the center of the basement. I am thinking it might be a nice space for an ice rink or tennis court 🤪.

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