Construction, standards and environment
backfill
In short and in plain language
Backfill is the material behind a wall that holds up a slope.
It fills the space between the wall and the soil.
It should let water through. Otherwise the water pushes against the wall.
Definition
Backfill is the material used to fill the space behind a retaining wall or next to a structure once it has been built. It should let water drain so that no pressure builds up behind the wall. Together with the foundation and drainage, it helps decide how long a wall lasts.