We purchased a new home in August of 2003 that has a concrete block foundation that is out of level. The house has a "daylight" basement so only the front and one side wall are concrete block and it is only a portion of the front wall that is out of level. To ensure level floors, the builder "shimmed" the I-beams and floor joists. By shimmed, he put one or more 5-6 inch wide wood or OSB squares (as deep as the sill plate) depending on what was needed to ensure that everything was level. The house has been constructed about two years and we have not had any problems to date, but I was wondering how this will hold up in the future. The builder says this is a common practice but would it be prudent to get a structural engineer's opinion? Any thoughts would be greatly appreciated. Thanks