Look before you leap into building on filled sites- or risk cracked foundations and lawsuits later on. by M. Daniel Gordon Few foundation topics generate as much confusion as does building on filled sites. Many home owners and contractors-and even some engineers -assume that filled sites offer good foundation support, particularly for residential or light-commercial structures. The assumption is that if someone took the time to fill a site, it must be better than it was before. This contrasts sharply with my experience, so my first reaction to a filled site is generally, How bad is the problem? When dealing with a filled site, a prospective developer or contractor should keep in mind the roadside signs that