Title 16 - Buildings and Construction

16.310 Residential Code

16.310.R405.1

Section R405.1 of the 2024 International Residential Code is hereby amended to read as follows:

R405.1 Concrete or masonry foundations. Drains shall be provided around all concrete or masonry foundations that retain earth and enclose habitable or usable spaces located below grade. Drainage tiles, gravel or crushed stone drains, perforated pipe or other approved systems or material shall be installed at or below the top of the footing or below the bottom of the slab and shall discharge by gravity or mechanical means into an approved drainage system. Gravel or crushed stone drains shall extend not less than 1 foot (305 mm) beyond the outside edge of the footing and 6 inches (152 mm) above the top of the footing and be covered with an approved filter membrane material. The top of open joints of drain tiles shall be protected with strips of building paper. Except where otherwise recommended by the drain manufacturer, perforated drains shall be surrounded with an approved filter membrane or the filter membrane shall cover the washed gravel or crushed rock covering the drain. Drainage tiles or perforated pipe shall be placed on not less than 2 inches (51 mm) of washed gravel or crushed rock not less than one sieve size larger than the tile joint opening or perforation and covered with not less than 6 inches (152 mm) of the same material.

Exceptions:

1.

A drainage system is not required where the foundation is installed on well-drained ground or sand-gravel mixture soils according to the Unified Soil Classification System, Group I Soils, as detailed in Table R401.4.1(2).
2.

A filter membrane is not required where perforated drains are covered with not less than 18 inches (457 mm) of washed gravel or crushed rock.
3.

A filter membrane is not required for gravel or crushed stone drains when the gravel or crushed stone extends not less than 18 inches (457 mm) above the top of the footing.

(History: Ord. No. BC-3513, §32, 2026; Ord. No. BC-3286 §64, 2020; Ord. No. BC-2936 §45, 2012)

Effective on: 1/1/1901