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Foundation Drain, Backfill & Rough Grading

Temporary Services  | Surveying and Layout | Excavation | Footings/Foundation  |  Foundation Options | Subrough Plumbing & HVAC | Dampproofing, Waterproofing and Window WellsWater and Sewer Laterals | >>Foundation Drain, Backfill and Rough Grade | Basement Slab

Foundation drain
Foundation drains are installed around the perimeter of the house to remove water that can flood basements or crawlspaces. Homes that are built on a hill side, on flood plains or high water table areas, commonly have foundation drains installed. Perforated pipe is placed at the base of the footing and covered by gravel. The gravel is then covered by a cloth membrane, which keeps sand, silt and other particles from plugging the holes in the drain pipe. As the water collects in the pipe it is removed either by gravity or a pump.

Backfill around the foundation and garage
After the laterals, window wells, dampproofing, and foundation drain are installed, the backfilling process begins. Care must be taken not to damage pipes, window wells, or the foundation itself. The foundation wall should be allowed to cure for at least 4-5 days in moderate weather, longer in very cold weather, prior to backfilling. It can easily be damaged by the force of dirt slamming against it or by the weight of the excavation machine if it gets too close to the foundation wall.
It is a good idea to compact the dirt in "lifts" as you are backfilling around the foundation. If the fill around the foundation is not compacted, it will invariably settle, and more dirt will need to be added later.
Some contractors use water to flood an area to facilitate settling. This may work in some soil conditions but it is not as effective as mechanical compaction. It is important to compact the fill in the garage or your garage slab will settle and crack excessively.

Fill the basement interior
After filling around the foundation, the level of the fill must be brought to the top of the footing and must be compacted to prevent the slab from excessive settlement. The plumbing and HVAC are covered with sand or pea gravel for protection. Some contractors also use pea gravel for under slab fill because is doesn't require compaction.
A small bobcat excavator may be lifted into the basement (by a track hoe) to assist the spreading of fill. The track hoe dumps the fill into the basement and it is spread and compacted in lifts of 4-6".

Rough grade
Now is a good time to coordinate the work between the excavators and the landscapers. Working together they should be able to shape the grade to the landscape plan. Dirt that will not be used for the landscaping or grading should be hauled away. If there is no landscape or grading plan, the lot should be graded so that water will run away from the house and toward the street (not towards the neighbors property).


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