Grading/slope around house and using gravel
stryped1
| Posted in General Questions on
I am in the process of re sloping around the foundation of my house. Can anyone recommend what slope I need?
Also, I have been thinking of using crusher run and tamp it to the proper slope around the foundation. Then installing black 6 mil plastic. On top of this my land scape river gravel. At the end of the slope would be a French drain.
Does anyone see any problems with using the crusher run to slope or using the plastic the way I am talking about?
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Replies
Dan,
The standard recommendation is that you need at least 6 inches of drop every 10 feet. That's a 5% grade.
Ideally, most of the backfill around your foundation (above the footing drain) is free-draining material like gravel or crushed stone, and the top few inches consists of a clay-rich topsoil to encourage drainage away from the foundation. Few builders achieve this, however.
You can proceed as you plan, but since the materials you are choosing are all free-draining, the "underground roof" details are very important. Without any soil or clay, the only thing stopping water is your proposed layer of plastic. EPDM roofing -- something fairly heavy -- would be better than 6 mil plastic.
For more information, see:
An Underground Roof
Ground Gutter
Fixing Those Drainage Problems, 30 Years Later
FHB: Inground gutters keep basements dry
GBA Encyclopedia: Inground Gutters
GBA Encyclopedia: Stormwater Management
GBA Encyclopedia: Roof Gutters
GBA Detail: Underground Water Barrier Retrofit