Drainage and damp proofing

Foundation drainage. Drains should 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 materials shall be installed at or below the area to be protected and shall discharge by gravity or mechanical means into an approved drainage system other than the sanitary sewer. 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 opening or perforation and covered with not less than 6 inches of the same material.

Masonry foundation damp proofing.   Foundation walls that retain earth and enclose habitable or useable spaces located below grade shall be damp proofed 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 damp proofed 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.

Concrete foundation damp proofing. Concrete walls shall be damp proofed by the same method as stated for masonry, or by a membrane extending from the top of the footing to the finished grade, plastic roofing cements, acrylic coatings latex coatings, cold setting or hot setting asphalts.

Concrete and masonry foundation waterproofing. 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.

Moisture control-concrete floors.    A 6 mil polyethylene or approved vapor retarder with joints lapped not less than 6 inches shall be placed between the concrete floor slab and the base course or the prepared sub-grade where no base course exists.

Exception: The vapor retarder may be omitted:

• From garages, utility buildings and other unheated accessory structures.
• From driveways, walks, patios and other flatwork not likely to be enclosed and heated at a later date.
• Where approved by the building official, based on local site conditions.