So, a big question that has always been at the forefront of my mind is how to built the house. To minimize energy costs, I’ve always wanted a well-insultated house (note that the exterior walls were always drawn to be a foot thick – that’s actually the plan). However, there are various methods for doing this. One method is insulating concrete forms. These are basically blocks of Styrofoam that act as a form for a concrete wall, and will sandwich the wall after pouring. There are upsides and downsides to building with concrete. One thing that can be a blessing and a curse is that concrete has a huge amount of thermal mass. Thermal mass is ideal if the the average of daytime and nighttime temperatures is a comfortable living temperature. Then thermal mass will keep you cool during the day and warm at night, because it will even out the extremes. However, concrete is a horrible insulator. Concrete has an R-value of 0.08 per inch. Soft wood will give you 1.25 (more than 15 times as much). Even single-pane glass will give you more insulation than a half foot of concrete. However, if you have concrete sandwiched in a large amount of insulation, its tendency to leak heat will be blocked by the enormous amount of Styrofoam on the other side. There will still be a large amount of thermal mass in the middle of the wall, but there will be multiple inches of insulation of either side of that mass. So, I think that will help control the difficulty one would have in heating a concrete structure, as well as maintaining proper moisture levels inside the house. (If you have poorly insulated concrete in a cool climate, the walls will be incessantly cold, and will cause condensation and thus mold.)
The big advantage of building with concrete to me is that it will easily enable a daylight walkout basement. (See notes at the bottom of About the House. Basically, a basement is not part of the square footage, so it won’t make us break the 1000-square-foot rule for second houses.) Basically, you have to do concrete walls for a basement, but as I noted above, normal concrete is just too non-insulated and it will draw in coldness from the outside ground. (And all the heating and moisture problems that go with that.) However, if I’m using insulating concrete forms for the main walls, it’s not too much of a stretch to go a bit further and use insulating concrete forms to build a basement as well. A bit advantage of having a basement is that you have super-easy access to all the utilities. Plumbing just drops through the floor, and then you have a nice, dry, open, tall area to work on your plumbing. I really dislike crawl spaces. They are dark, damp, and not tall enough to work in. I like slabs, but they lack flexibility for changes. A basement allows you extra-easy access for all your plumbing and electrical work.
Also, the insulating concrete forms allow for more flexible house shapes than some of the kits I looked at previously. So, now I’m considering a 50-foot by 20-foot house in the basic configuration of a left-bedroom, a right-bedroom and a center kitchen-living-dining area. A spiral staircase would lead to the basement. All utilities (water heater, breaker box, etc) would be in the basement.
They are basically Lego blocks. You have two parallel rows of Lego blocks, held together by plastic ties. The plastic ties keep the forms from sliding away from each other. They also serve as a point to hold both horizontal and vertical re-bar. And then they also serve as a material for affixing siding on the outside and drywall on the inside. (However, it seems that you can also apply stucco directly to the outside, which will probably be my path. Nadja is from Germany, and stucco is a very common German look and I think she’d appreciate that.)