The following rules are found in the 2003 International Residential Code and apply to all new dwellings and townhouses. (IRC Sections 405 and 406)
Drains shall be provided around all concrete and 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 materials shall be installed at or below the area to be protected and shall discharge by gravity or mechanical means into an approve drainage system. Gravel or crushed stone drains shall extend at least 1 foot beyond the outside edge of the footing and 6 inches 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, and the drainage tiles or perforated pipe shall be placed on a minimum of 2 inches of washed gravel or crushed rock at least one sieve size larger than the tile joint openings or perforation and covered with not less than 6 inches of the same material.
A drainage system is not required when the foundation is installed on well-drained ground or sand-gravel mixture soils according to the Unified Soil Classification System, Group I Soils.
In areas where a high water table or other severe soil-water conditions are known to exist, exterior foundation walls that retain earth and enclose habitable or usable spaces located below grade shall be waterproofed with a membrane extending from the top of the footing to the finished grade. The membrane shall consist of 2-ply hot-mopped felts, 55 pound roll roofing, 6-mil polyvinyl chloride, 6-mil polyethylene, or 40-mil polymer-modified asphalt. The joints in the membrane shall be lapped and sealed with an adhesive compatible with the waterproofing membrane.
Exterior foundation walls that retain earth and enclose habitable or useable space below grade and that are not required to be waterproofed shall be dampproofed from the top of the footing to the finished grade. Masonry walls shall have not less than 3/8-inch Portland cement parging applied to the exterior of the wall. The parging shall be dampproofed with a bituminous coating, 3 pounds per square yard of acrylic modified cement, 1/8-inch coat of surface-bonding mortar complying with ASTM C 887 or any material permitted for waterproofing above.
Concrete walls shall be dampproofed by applying any one of the above listed dampproofing materials or waterproofing materials listed above.
For wood foundations, see the International Residential Code.
For more information, contact at 952-548-6320.