100 year home that began as a cottage on a basement foundation, but ended up with 3 bump out additions on crawl spaces. Two are on the north side and 1 addition is on the south side. The house has been gutted, and there are separations between the floor and side walls where they attach to the original cottage. The separations vary from 1/2 inch at the floor to 2 inches at the side walls as they have pulled away from the cottage. A structural engineer is not concerned. Looking for a way to fill the gap separations to keep out insects and air.