and Layout | Excavation
Options | Subrough
Plumbing & HVAC | Dampproofing,
Waterproofing and Window Wells | Water
and Sewer Laterals | >>Foundation
Drain, Backfill and Rough Grade | Basement
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.
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
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
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.
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".
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).