While the house is being built at the factory, the final preparations are being made to the lot. These include pouring the footers and then constructing the walls for a basement or crawl space (depending on which you want). The walls can be made of either poured concrete or with cinder blocks. After the concrete is hardened, a knee wall is built along the top. This is what the house will sit on once it is lifted onto its foundation. For houses that will have a basement, the floor is usually poured after the house is delivered.
