Drainage Gravel Around a House Foundation

Drainage gravel around a house foundation helps water move away from basement and crawlspace walls instead of soaking the soil against them. It shows up in two places: around footing drains at the bottom of the foundation, where clean stone surrounds a perforated pipe, and at the surface, where a gravel strip along the house catches roof drip and keeps soil from splashing on siding. In both cases the best choice is clean, washed stone with no fines, such as #57 or 3/4-inch stone, used with filter fabric and with the ground sloping away from the house.

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Footing drains

At new construction or during excavation repairs, a perforated drain pipe is laid beside the footing and surrounded by clean stone.

Component	Typical spec
Stone	Clean, washed #57 or 3/4 in
Stone around pipe	About 6 in under, around, and over
Fabric	Nonwoven filter fabric wrapped around stone
Pipe	Perforated, holes facing down, sloped to an outlet or sump

The fabric keeps soil from clogging the stone. Some builders also run clean stone up the wall as backfill, or use a dimpled drainage mat against the wall. See number 57 stone.

Surface gravel strips

A strip of gravel along the foundation, often 18 to 36 inches wide and 3 to 4 inches deep, is common under roof edges without gutters. It reduces splashing, erosion, and mud against siding.

Remove sod and slope the soil away from the house.
Lay landscape fabric. See landscape fabric under gravel.
Install edging on the lawn side.
Add 3 to 4 inches of clean stone.

Grading comes first

Gravel does not fix bad grading. Building codes commonly call for the ground to fall at least 6 inches within the first 10 feet from the foundation where possible. If soil slopes toward the house, gravel will simply hold water against the wall. Regrade with compacted soil first, then add gravel.

Common mistakes

Using stone with fines, which packs and holds water.
Burying downspouts in gravel without piping them away.
Piling gravel or mulch above siding or close to wood framing.
Skipping fabric, letting soil clog the stone over time.

Downspouts should discharge several feet from the house, through extensions or solid pipe.

How much stone

A 30-foot wall with a 2-foot-wide strip at 4 inches deep needs 20 cubic feet, about 0.75 cubic yard or roughly 1 ton. Use the asphalt base calculator for other sizes.

Retaining walls

Retaining walls use the same principle: clean stone behind the wall with a drain pipe at the base. See crushed stone for retaining wall backfill.

When to call a pro

Persistent basement water, cracks, or hydrostatic pressure may need interior drainage, waterproofing, or regrading by a contractor.

Bottom line

Use clean, washed stone like #57 or 3/4-inch around foundation drains and in surface strips, wrap it in filter fabric, and make sure the ground slopes away from the house. Gravel helps water move, but grading and downspout extensions do most of the work.

Questions people ask

What gravel is best around a foundation?

Clean, washed stone like #57 or 3/4-inch, with no fines.

Does gravel around a house help drainage?

Yes, if the ground slopes away and the stone is clean.

How wide should a gravel strip around a house be?

Often 18 to 36 inches, depending on roof overhang and drip line.

Should I use fabric under foundation gravel?

Yes, to keep soil from clogging the stone.

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