Building a Home – Putting Down the Foundation
After the home site had been prepared, things started to happen quickly. A couple days after the heavy equipment left, a work crew came by and put up the foundation forms. Soon after, they returned with several truckloads of sand and backfilled the forms. The basics of a monolithic slab foundation are 20″ concrete footers around the perimeter and 4″ of concrete everywhere else. The footers provide a stable, strong foundation on which to build the weight bearing walls using concrete that is rated to 3000 pounds per square inch.
With the forms in place, plumbers visited the job site. They dug trenches in the sand to run the water supplies, drainage lines, electrical conduit, and radon exhaust. Keep in mind that all of this is going to be buried under 4″ of concrete, so there’s not much room for error. The plumbing was done with various sorts of plastic depending on the application. Besides its cost, versatility and ease of use, plastic is also a poor conductor so you can count on hot water staying hot and cold water staying cold. When all the plumbing was down, they filled the trenches and put a layer of plastic over everything to serve as a vapor barrier. Since concrete inevitably cracks, the plastic will prevent moisture and gas (especially radon) from seeping up into the house (see the YouTube video here).
Everything was ready for concrete. It came in 6 massive trucks. We were told the concrete they had ordered contained synthetic fibers that would help bind the concrete together. We were also told the concrete would begin to set in about 90 minutes. Sometimes, concrete trucks have problems that don’t allow the drivers to unload their concrete before it sets. If that happens, they have to get inside the concrete drums and chisel or jack hammer the concrete out. Needless to say, the concrete contractors worked with a purpose. They seemed to follow a three step process: 1) move the concrete around with shovel-like implements, 2) use a 2×4 and preset rebar spikes for leveling, and 3) apply a smooth coat to the surface with a bull float.
Sara and I got to the home site at about 7:30am that morning, just as they began to pour the concrete. When we came back at 5:00pm, the work crew had removed the forms and the concrete had hardened enough to stand on. The foundation was done just like that (see the video here).