PNNL. 2012. Building America Case Study: New Traditions Homes, Landover Commons, Vancouver, WA. PNNL-SA-87320, prepared by the Pacific Northwest National Laboratory for the U.S. Department of Energy Building America Program.
Final Grade
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Scope
Water Managed Site and Foundation
Back-fill has been tamped and final grade sloped ≥ 0.5 inch per foot away from home for ≥ 10 feet. See note below for alternatives.
- Slope final grade away from the house at least 0.5 inch per foot for 10 feet.
- Back-fill tamp to prevent settling.
If setbacks limit the space to less than 10 feet, install either:
- Swales
- Drains designed to carry water away from the foundation.
Note:
Where setbacks limit space to less than 10 feet, swales or drains designed to carry water from foundation shall be provided. Also, tamping of back-fill is not required if either: proper drainage can be achieved using non-settling compact soils, as determined by a certified hydrologist, soil scientist, or engineer; OR, the builder has scheduled a site visit to provide in-fill and final grading after settling has occurred (e.g., after the first rainy season).
What are swales? Swales are typically vegetated, trapezoidal channels, which receive and convey storm water flows. The swale not only aids in storm water flows, but also removes pollutants through vegetation. With the selection of correct planting materials, swales can be an attractive alternative both visually and monetarily.
Back-fill tamping is not required if either: proper drainage can be achieved using non-settling compact soils, as determined by a certified hydrologist, soil scientist, or engineer; OR, the builder has scheduled a site visit to provide in-fill and final grading after settling has occurred (e.g., after the first rainy season).
To find out more information and the best plants to use, it is best to contact a local cooperative extension program based at land grant universities. For a list of cooperative extension programs across the nation, see the eXtension Website.
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Description
Because no waterproofing system is 100% foolproof, the best defense against water intrusion through the foundation is to prevent water from saturating the soil around the foundation. This can be done by constructing the foundation and grading the site so that water drains away from the house on all sides.
How to Grade the Site
- Grade to build up the site before construction, if needed, to raise elevation of walls above grade.
- After construction, back-fill, grade slope, cap with 2 to 4 inches of silty clay, and mechanically compact it to achieve a final grade slope of ≥ 0.5 inch per foot away from home for ≥ 10 feet.
- Tamping of back-fill is not required if either: proper drainage can be achieved using non-settling compact soils, as determined by a certified hydrologist, soil scientist, or engineer; OR, the builder has scheduled a site visit to provide in-fill and final grading after settling has occurred (e.g., after the first rainy season). See note below for alternatives.
- If setbacks limit the space to less than 10 feet, install either: swales or perimeter drains designed to carry water away from the foundation. (Swales are typically vegetated, trapezoidal channels, which receive and convey storm water flows. Swales slow storm water runoff and remove pollutants through vegetation.)
Figure 1 - Site grading and groundwater control 
Ensuring Success
Visually inspect that back-fill has been tamped and final grade sloped ≥ 0.5 in. per ft. away from home for ≥ 10 ft. Where setbacks limit space to less than 10 ft., see that swales or drains are installed to carry water from foundation shall be provided.
Climate
No climate specific information applies.
Right and Wrong Images
Presentations
None Available
Videos
None Available
CAD Images
None Available
Compliance
ENERGY STAR Version 3, (Rev. 6)
Water Management System Builder Checklist, Water-Managed Site and Foundation. Back-fill has been tamped and final grade sloped ≥ 0.5 in. per ft. away from home for ≥ 10 ft. Where setbacks limit space to less than 10 ft., swales or drains designed to carry water from foundation shall be provided. Also, tamping of back-fill is not required if either: proper drainage can be achieved using non-settling compact soils, as determined by a certified hydrologist, soil scientist, or engineer; OR, the builder has scheduled a site visit to provide in-fill and final grading after settling has occurred (e.g., after the first rainy season).
DOE Challenge Home
Exhibit 1: Mandatory Requirements. Certified under ENERGY STAR Qualified Homes Version 3.
Section R408.6 Finished grade. Finished grade of under-floor surface may be located at the bottom of the footings. If there is evidence that the groundwater table can rise to within 6 inches of finished floor at the building perimeter or where there is evidence that surface water doesn’t readily drain from the building site, the grade in the under-floor space must be as high as the outside finished grade unless an approved drainage system is provided.*
Section R408.6 Finished grade. Finished grade of under-floor surface may be located at the bottom of the footings. If there is evidence that the groundwater table can rise to within 6 inches of finished floor at the building perimeter or where there is evidence that surface water doesn’t readily drain from the building site, the grade in the under-floor space must be as high as the outside finished grade unless an approved drainage system is provided.*
*Due to copyright restrictions, exact code text is not provided. For specific code text, refer to the applicable code
References
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DOE Challenge Home National Program Requirements
DOE. 2012. DOE Challenge Home National Program Requirements (Rev. 02). Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy, Washington, D.C.
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ENERGY STAR Qualified Homes, Version 3 (Rev. 06) Inspection Checklist for National Program Requirements
EPA. 2012. ENERGY STAR Qualified Homes, Version 3 (Rev. 06) Inspection Checklist for National Program Requirements. U.S. Environmental Protection Agency, Washington, D.C.
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Groundwater Control, Information Sheet 101
Building Science Corporation. 2009. Groundwater Control, BSC Information Sheet 101. Prepared by Building Science Corporation for the U.S. Department of Energy, Building America Program.
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Water Management System Builder Checklist Guide
EPA. 2011. Water Management System Builder Checklist Guide. U.S. Environmental Protection Agency, Washington, D.C.
