N.Y.C. Admin. Code § BC 1805: Section BC 1805: Dampproofing and Waterproofing

1805.1 Where required.

Walls or portions thereof that retain soil or rock and enclose interior spaces and floors below grade shall be waterproofed or dampproofed in accordance with this section, with the exception of those spaces containing occupancy groups other than residential and institutional where such omission is not detrimental to the building or occupancy. Ventilation for crawl spaces shall comply with Section 1203.3.

1805.1.1 Flood hazard areas.

Buildings and structures in areas of special flood hazard shall comply with Appendix G.

1805.2 Dampproofing required.

Where hydrostatic pressure will not occur as determined by Section 1803, floors and walls for other than wood foundation systems shall be dampproofed in accordance with this section. Wood foundation systems shall be constructed in accordance with AWC TR7.

1805.2.1 Floors.

Dampproofing materials for floors shall be installed between: (i) the floor and (ii) the base course required by Section 1805.4.1 or the sub-floor. Subgrade for the dampproofing material shall be prepared in accordance with manufacturer's recommendations. Dampproofing material shall be installed in accordance with manufacturer's recommendations and protected after placement. Any damaged areas and punctures must be repaired prior to placement of slab. All penetrations shall be sealed as per manufacturer's recommendations.

1805.2.2 Walls.

Dampproofing materials for walls shall be installed on the exterior surface of the wall, and shall extend from the top of the footing to above ground level as determined by the registered design professional and shall be installed in accordance with manufacturer's recommendations. Dampproofing at walls shall overlap or extend past the slab dampproofing such that there are no gaps or breaches in the dampproofing system.

1805.3 Waterproofing required.

Where the geotechnical investigation required by Section 1803 indicates that a hydrostatic pressure condition exists, walls and floors shall be waterproofed in accordance with this section.

1805.3.1 Floors.

Floors required to be waterproofed shall be designed and constructed to withstand the hydrostatic pressures to which the floors will be subjected. Waterproofing shall be accomplished by creating a continuous water seal below the floor using appropriate waterproofing materials. Joints, penetrations and other interruptions shall be sealed in accordance with manufacturer's recommendations. Floor waterproofing must be transitioned to accomplish a complete tie-in with the foundation wall waterproofing.

1805.3.2 Walls.

Walls required to be waterproofed shall be designed and constructed to withstand the hydrostatic pressures and other lateral loads to which the walls will be subjected. Waterproofing shall be applied from the bottom of the wall to not less than 12 inches (304.8 mm) above the maximum elevation of the groundwater table or as directed by the registered design professional. The remainder of the wall shall be dampproofed in accordance with Section 1805.2.2. Joints, penetrations and other interruptions shall be sealed in accordance with manufacturer's recommendations.

1805.3.3 Joints and penetrations.

Joints in or between walls and floors, and penetrations of walls and floors shall be sealed utilizing methods and materials approved by the registered design professional. Joints, penetrations and other interruptions shall be sealed in accordance with the manufacturer's recommendations.

1805.4 Subsoil drainage system.

Where it is determined that there is a potential for infiltration or seepage, a subsoil drainage system shall be permitted to be used to control this inflow, provided that:

1. The below ground space is waterproofed or dampproofed per Sections 1805.2 and 1805.3; and

2. The estimated discharge from the drainage system is less than or equal to the amount allowed by the agency having jurisdiction.

1805.4.1 Drainage course.

A drainage course shall consist of washed gravel, crushed natural stone or other suitable drainage medium acceptable to the engineer. Recycled concrete aggregate is not acceptable for use in a drainage course where a subsoil drainage system is used.

1805.4.2 Foundation drain.

A foundation drain shall be installed where required by the registered design professional. The foundation drain, including layout, materials, and cleanouts, shall be designed by the registered design professional.

1805.4.3 Drainage discharge.

The drainage course and foundation drain shall discharge by gravity or mechanical means into an approved drainage system that complies with the New York City Plumbing Code and any other laws or requirements of agencies having jurisdiction.

1805.5 In situ walls.

In situ walls (such as slurry walls, tangent pile walls, and secant pile walls) with joints sealed by grouting or other methods acceptable to the engineer shall not require waterproofing or dampproofing unless required by the engineer.