1. Brace the Concrete Wall Backfilling a freshly built concrete …
1. Brace the Concrete Wall Backfilling a freshly built concrete wall can cause it to bulge or crack, requiring a costly fix. If the floor deck isn’t installed, brace the basement walls first using heavy timbers at about two-thirds of the wall height, and about 12 feet apart (for an 8-foot wall).
Harry Whitver
2. Use Coarse Granular Material Cover the footing drains with gr…
2. Use Coarse Granular Material Cover the footing drains with gravel and filter fabric. If the existing site soils contain clay or organic matter, bring in better fill to complete the backfilling. “Pit run” or “bank run” gravel makes an economical and effective fill.
Harry Whitver
3. Compact the Backfill Compacting the backfill as you place it …
3. Compact the Backfill Compacting the backfill as you place it will prevent the surface from settling over time—you don’t want to end up with a slope that drains toward the house. Best practice is to place your material in 6-inch to 12-inch lifts, and to compact it by hand using a “jumping jack” compactor.
Harry Whitver
4. Slope the Final Grade Set the finish grade so that there’s …
4. Slope the Final Grade Set the finish grade so that there’s a good positive slope away from the foundation for drainage. About 6 inches of slope in 10 feet is a good rule of thumb, but making the slope a bit steeper to allow for possible settling won’t hurt.
It’s not about curb appeal, but the way you backfill a foundation makes a difference to a home’s real value. Good backfill should be well-compacted and stable to ensure it won’t settle over time and won’t apply too much pressure to the basement walls. It should be coarse, well-draining material to help keep the basement dry. Site soils are fine if the natural soil in the area is mainly sandy or gravelly, but don’t use the existing soil from the site for backfill if it contains clay or organic material.
Whatever the material, backfilling a basement foundation puts a momentary stress on the walls. Let the concrete cure for at least a week before backfilling (28 days is best). Place and compact the backfill carefully in partial lifts—don’t dump it all in at once. And if you have to backfill before the floor system is framed, support the walls first with sturdy diagonal bracing.
