Q. I would really like to build a concrete home using cast-in-place forms. I am not talking about one of the new insulated-concrete-form (ICF) systems that use foam blocks. I can’t find anyone who has built a home using traditional foundation forms. Realtors and salespeople at model homes look at me like I am from outer space. Is it not a good idea to build a simple concrete home? Why aren’t more of them built here in the United States? — Mark W., Bushkill, Pa.
A. Building a home with concrete is nothing new. In fact, there are all sorts of variations on the theme. There is a 50-year-old cast-in-place concrete home you would drool over that is just 1/2 mile from my own home.
It is an authentic, one-of-a-kind Frank Lloyd Wright home that is on the National Register of Historic Places. This drop-dead gorgeous solid-concrete home takes my breath away each time I see it. Even its individual windows are cast into the concrete!
First and foremost, I think the single-largest obstacle to building with concrete in the manner in which you speak — cast-in-place forms — is the overall cost. It can be expensive to build in this manner, and the other subcontractors that come after the concrete people leave have lots of extra work to do.
The cost issues of building a cast-in-place home are significant. It is somewhat labor-intensive to attach interior mechanical systems of electric, plumbing and heating and cooling to solid concrete. Drywall can be directly applied to concrete that is very smooth, but not all traditional concrete forms produce smooth finished surfaces.
There are also significant energy issues with respect to solid concrete or masonry structures of any type. Concrete is a conductor of heat, not an insulator. But when you combine concrete with superb insulation, you connect for a home run. This is why the ICF homes are currently gaining popularity; they have all the positives of concrete and all of the super-insulation aspects many of us who live in traditional homes would kill for.
Because of the extra-thick concrete walls, the typical doors and windows you would use almost always require extra wood and labor when they are trimmed out. The stark exterior of the cast-in-place concrete would have to be disguised with stucco or some other wall covering to ensure your home doesn’t appear to be a tilt-up concrete warehouse in an industrial park. I don’t dislike tilt-up concrete walls, but your neighbors might not be so tolerant.
Connecting traditional wood floor joists can be placed in cast-in-place concrete, but it is not as easy as nailing them to the top plate of wood-framed walls. Insulating the exterior walls of your proposed solid-concrete home can be done, but once again it almost always costs more than placing pre-sized fiberglass batts in wood-framed wall cavities. The newer blown-in wall insulation products also prefer a wood or steel framing cavity so the thickness of the insulation remains uniform.
Don’t forget that traditional cement-stucco homes are basically concrete homes. Coarse sand mixed with Portland cement makes a layer of concrete that has nearly the same compressive strength as regular concrete. Perhaps you should consider blending the wood-framing building techniques most builders and subcontractors prefer with a concrete outer skin.
It seems to me this would give you the look you might want on the exterior as well as the superb maintenance-free outside characteristics. You never have to paint the stucco, and if you desire it to be a particular color or want different colors, permanent dry pigments can be blended into the wet stucco. The finished look can be stunningly beautiful.
I also urge you to consider other concrete systems. There are all sorts of imaginative ways concrete is being used to build homes. For example, you can have a solid-concrete home built using lightweight concrete blocks that contain vast amounts of air. These blocks remind me of ultra-fine volcanic pumice. They stack together easily and provide a superb surface for stucco and interior drywall.
You may be able to find a regional company that will build precast concrete walls with integral interior wood framing that will keep the subcontractors happy. These walls are built in a factory and lifted into place with a crane. They bolt together much like you would connect a kitchen cabinet to an adjacent one. Contact one or more of the associations that promote the use of concrete. I’ll bet they will help you build the house of your dreams!
