RoofingCode: Section 1505
Roof Assemblies

Section 1505.2 Wind Resistance of Low-Slope Roof Systems. The low-slope roof systems described in Section 1507.5 which are mechanically attached, adhered to the roof deck or ballasted shall be designed to resist the design wind load pressures of Section 1609.0. Roof systems with built-up, modified bitumen, fully adhered or mechanically attached single-ply, metal panels, and other types of membrane roof coverings shall also be tested in accordance with FM 4450, FM 4470, UL 580 or UL 1897 listed in Chapter 35.

Code Interpretation

This code implies that all low-slope roof systems shall be designed and installed to meet wind resistance requirements. Wind resistance for roof systems is primarily wind-uplift resistance. Section 1609.0 (referenced in the code) states, “All buildings, other exposed structures, components, cladding and roof coverings shall be designed to resist the pressures caused by wind in any direction as provided for herein … .” The provisions and formulations provided in Section 1609.0 are identical to formulations used by ASCE and Factory Mutual. The section provides the required reference material to determine wind-uplift resistance for specific structures. The procedure to determine roof wind uplift classifications on specific buildings during the design phase is based a calculation that takes into account the basic wind speed in the geographical area, ground surrounding the building and the roof uplift pressure at the field of the roof. The building’s height and perimeter construction is also considered. It is the responsibility of the specifier to complete these calculations. It is the specifiers’ responsibility to determine the proper wind uplift classification for the building.

The code also states the all applied roof materials shall be tested and approved for use by FM (Factory Mutual) and UL (Underwriters Laboratories). Required FM testing is conducted in accordance with their standard 4450-90, Approval Standard for Class I Insulated Steel Deck Roofs, and 4470 – 86, Approval Standard for Class I Roof Coverings. The required UL testing is standard 580 – 94, Test for Uplift Resistance of Roof Assemblies. This provides a departure from conventional thinking that only Factory Mutual Insured properties must meet their wind-uplift and testing standards.

For further clarification of these references, you can contact the organizations directly:

American Society of Civil Engineers (ASCE)
1801 Alexander Bell Drive
Reston, VA 20191

Underwriters Laboratories (UL)
333 Pfingsten Road
Northbrook, IL 60062-2096

Factory Mutual (FM)
Standards Laboratories Dept.
1151 Boston Providence Turnpike
Norwood, MA 02062

WaterproofingCode: Section 1807
Dampproofing and Waterproofing

1807.3, Waterproofing Required. Where the ground-water investigation required by Section 1802.2.3 indicates that a hydrostatic pressure condition exists, and the design does not include a ground-water control system as described in Section 1807.1.3, walls and floors shall be waterproofed in accordance with this section.

Interpretation of the Code

This section implies that a waterproofing application is completed when the site ground water table is maintained at an elevation of not less than 6 inches below the bottom of the ground slab. The section states that waterproofing is required when hydrostatic pressure will occur.

It is the responsibility of the architect or designer to make certain that the waterproofing component is in compliance with the applicable federal, state or local codes. The primary distinction of the codes is in regard to water table and hydrostatic pressure. A proper engineering study of the grounds is required to establish this criterion for the design phase. ASTM states that dampproofing or waterproofing is required for slabs on ground and foundation retaining walls.