CALGreen Section: 5.106.10 Grading and Paving. Construction plans shall indicate how site grading or a drainage system will manage all surface water flows to keep water from entering buildings. Examples of methods to manage surface water include, but are not limited to, the following:
1. Swales; 2. Water collection and disposal systems; 3. French drains; 4. Water retention gardens;
5. Other water measures which keep surface water away from buildings and aid in groundwater recharge
Intent:
The intent of this code provision is to ensure that newly constructed project sites are planned and developed to keep surface water from entering the building, to extend the longevity of the exterior building walls, to prevent mold and keep moisture from entering the exterior wall and perimeter slabs.
Change for 2012: This provision is being modified slightly to emphasize means of compliance. Grading and paving plans, typically required by enforcing agencies, will show how this is to be accomplished, and a list of methods for managing flows, aligned with the Department of Housing and Community Development’s (HCD) section, has been added.
Existing Law or Regulation:
There is NO current law or regulation for this code provision. However, there are some code sections in the California Building Code (for example Section 1805.3.4 Foundation elevation) that address sloping grades away from buildings but does not address how all surface water flows will be managed on site.
Compliance Method:
Show on the construction documents (site plan or grading plan) how site grading and/or a drainage system will manage all surface water flows to keep water from entering the building. This is particularly critical on sloped sites.
Suggestion: Show on the grading plan, in addition to draining the water away from the exterior walls, how surface water will be managed on site. Methods include but are not limited to, those now listed in the regulation.
Enforcement:
Plan Intake: The reviewer and/or plan checker should review the grading plan and confirm that there are slopes away from the building and adequate measures to manage surface water flows. In addition, the reviewer should ensure that the plans indicate protection from water intrusion for buildings located on sloped sites or having flood plain requirements.
On-Site Enforcement: The inspector should review the permit set of plans to verify that all grading and/or drainage systems have been installed as specified on the approved plans and specifications.
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