The top of the drain shall be covered with an approved filter membrane material. Where a drain tile or perforated pipe is used the invert of the pipe or tile shall be placed higher than the floor elevation. The pipe or tile shall be placed on not less than 2 inches of gravel or crushed stone complying with Section 1807.4.1, and shall be covered with not less than 6 inches of the same material.

Code Interpretation

This section provides the requirements for foundation drain placement. The section is precise in the requirements and provides a basis for design:

1. Apply a drain around the perimeter of the foundation that consists of gravel or crushed stone. The gravel or crushed stone shall be a minimum of 4.75 mm or larger.
2. The drain shall extend a minimum of 12 inches beyond the outside edge of the footing.
3. The thickness shall be such that the bottom of the drain is not higher than the bottom of the base under the floor, and that the top of the drain is not less than 6 inches above the top of the footing.
4. Cover the top of the drain with an approved filter material.
5. If a drain tile or perforated pipe is used the invert of the pipe or tile shall be placed higher than the floor elevation.
6. The pipe or tile shall be placed on a minimum of 2 inches of gravel or crushed stone. The gravel or crushed stone shall be a minimum of 4.75 mm or larger.
7. The completed pipe or tile shall be covered with a minimum of 6 inches of gravel or crushed stone. The gravel or crushed stone shall be a minimum of 4.75 mm or larger.