What is backfill in construction?

In construction, backfill replaces soil that is removed during building construction, and it is used to strengthen and support a structure's foundation. Backfill is generally a combination of soil, stones and rocks.

The areas around the foundation are graded with backfill to promote better water drainage, according to From Plat to Place. Backfilling requires compacting layers of filler in 12-inch intervals until the material is even with the ground surrounding it. Wollam Construction advises that the foundation be sealed and the local building codes verified before beginning the backfill. Upon completion, sod or grass may be planted to blend with surrounding areas.