§ 4-251. Foundations; Section R-405, Foundation Drainage.

(a)

The following amendments, additions, and/or deletions are made to Section R-405 of the International Residential Code:

(1)

Section R-405.1.2, Subsoil Drainage Systems. Subsoil drains shall be required for all buildings having basements, cellars, crawl spaces, or floors below grade. Subsoil drains shall be located inside and outside of the foundation and shall be installed at or below the area to be protected. Drains shall discharge by gravity or mechanical means into an approved drainage system.

(2)

Section R-405.1.3, Sump Pumps and Pits. Where subsoil drains do not discharge by gravity, the drains shall discharge to an accessible sump pit with an automatic electric pump. A battery back-up or water-powered back-up sump pump will also be provided. The sump pit shall be a minimum of twenty-four (24) inches in diameter or eighteen (18) inches square and twenty-four (24) inches in depth, and be provided with a fitted cover. The sump pump shall have adequate capacity to discharge all water coming into the sump as it accumulates but in no case shall the capacity of the pump be less than fifteen (15) gallons per minute. The discharge from the pump shall be a minimum of one and one-fourth (1¼) inches and shall have a union in the discharge piping to make the pump accessible for servicing. Subsoil drains and sump pump discharge may discharge to a properly graded open area provided the point of discharge is ten (10) feet from any property line or Building Restriction Line (BRL). Where a continuously flowing spring or high groundwater table is encountered during the design stage, basement floors shall be designed at least two and one-half (2.5) feet above the groundwater's highest detected level. Alternatively pre-approved methods of permanent dewatering shall be provided, and the groundwater level shall be verified again before construction. If such condition is encountered by the County and subsoil drains are pre-approved by the County; these drains must be piped to a storm drain or approved outfall where they shall be fitted. When piped to a storm drain all drainage lines shall include an accessible backwater valve. Residential sump pumps are not to be relied on for lowering high groundwater table.

(3)

Section R-405.1.4, Areaway Drains. All open subsurface space adjacent to a building serving as an exit or entrance shall be provided with a drain or drains. Such areaway drains shall be of approved material in accordance with Chapter 30 of this Code and not less than 2 inches in diameter and shall discharge by gravity or mechanical means in accordance with R-405.1.2. Areaway drains for areas exceeding 800 square feet shall be sized in accordance with Section 1113 of the 2006 International Plumbing Code.

(4)

Section R-405.1.5, Window Well Drains. Window well areaways shall have drains. Window well areaways 10 square feet or less may discharge to the subsoil drain through a 2-inch minimum diameter pipe. Drains for window well areaways greater than 10 square feet shall be installed in accordance with Section R-405.1.3.

(5)

Section R-405.1.6, Foundation Weep Holes. Where subsoil drains are required by Section R-405.1.1, foundations of hollow core masonry shall have foundation weep holes. Weep holes shall be placed a maximum of 4-foot o/c intervals and shall discharge into the aggregate of the interior subsoil drainage system.

(6)

Section R-405.1.7, Site Grading. The ground immediately adjacent to the foundation shall be sloped away from the building at a slope of not less than one unit vertical in 12 units horizontal (1:12) for a minimum distance of 5 feet (914 mm) measured perpendicular to the face of the wall or an approved alternate method of diverting water away from the foundation shall be used. Consideration shall be given to the possible additional settlement of the backfill when establishing the final ground level adjacent to the foundation.

(7)

Section R-405.2, titled "Wood foundations" is deleted in its entirety.

(CB-13-2009; CB-45-2012; CB-90-2015)