Laying the Foundations

This spring, I am very fortunate to have the opportunity to work with a natural builder on his very own straw bale house. Mark Rogers is one of a few builders in the area, with experience in stone masonry as well as straw bale construction, and he has graciously allowed me to tag along and "help" (learn) from him through the process.

I met Mark towards the end of last summer (2014), when he was in the process of pouring the concrete foundation for his small house. It is about 1000 sq ft, not counting a second story loft, and the floating slab foundation serves as the floor of the interior space. Here is a quick diagram of a basic floating slab foundation, though there are several variations. 

Image from:
http://www.barntoolbox.com/foundation-types.htm

Mark's foundation is a little different. There is not only rebar in the thicker portions that will support the walls, but there is also welded wire reinforcement throughout the slab. The concrete is also completely insulated with 5 inches of foam insulation underneath. This way, he can take advantage of the foundation/floor's thermal mass. He has also put in a radiant floor heating system, which will run hot water through small pipes embedded in the concrete and heat the floor. That will be super cozy and nice during the winter. Here are some pictures of the form before the concrete was poured. 

Another thing that is different about Mark's foundation is that there are a few dozen pieces of rebar sticking up about 3 feet high all around the edge of the slab. This is a picture of the slab covered for the winter. Mark used straw and foam insulation underneath a sheet of plastic to help protect the concrete from thermal stress and the elements. You can see here the rebar I was talking about. These rebar posts are anchored into the concrete slab and will serve to anchor the stone wall that will lie underneath the straw bales. 

There are a few advantages to having a stone wall. Not only will it be very beautiful when completed, but the stone wall will raise the straw bale up from the ground and protect it from water damage. Plaster often gets worn away by the splash of rain water falling off the eaves of the roof. It seems minor, but years of splash can really damage the plaster and straw bale. 

Hopefully I will figure out a way to scan and upload some of the technical drawings to illustrate the plan for the next stages of construction. I'll keep you posted!