Roofing Code: Chapter 15

Roofs and Roof Structures

Section 1507.13, Thermoplastic Single-Ply Roofing:

The installation of thermoplastic single-ply roofing shall comply with the provisions of this section.
1507.13.1, Slope. Thermoplastic single-ply membrane roofs shall have a design slope of a minimum one-fourth unit vertical in 12 units horizontal (2 percent slope) for drainage.
1507.13.2 Material Standards. Thermoplastic single-ply roof coverings shall comply with ASTM D 4434, ASTM D 6754, ASTM D 6878 or CAN/CGSB 37-54.

Code Interpretation

This section implies that thermoplastic roof systems shall be applied on roof substrates that have a minimum slope of 2 percent or ¼ inch in 12 inches. Proper roofing industry standards require that the slope of the deck shall be sufficient to remove all standing water from the roof system a maximum of 48 hours after a rainfall. The roof deck slope must comply with IBC requirements (¼ inch in 12 inches). If this slope is not adequate to remove all standing water from the system, artificial means (such as tapered insulation) may be required.

The section also implies that the thermoset materials must meet the requirements set forth by ASTM (American) or CGSB (Canadian) standards for physical property testing. Physical property tests typically include moisture resistance, tensile, elongation, mil thickness, accelerated weathering and wind uplift testing.

Waterproofing Code: Section 1807

Dampproofing and Waterproofing

Section 1807.3.1, Walls:

Walls required to be waterproofed shall be of concrete or masonry and shall be designed and constructed to withstand the hydrostatic pressures and other lateral loads to which the walls will be subjected.

Code Interpretation

This section implies that all walls that require waterproofing shall be constructed of concrete or masonry and shall be of structural integrity to withstand hydrostatic pressure and lateral loads.

The waterproofing applied at the walls shall consist of one of the following membranes:

• Two-ply hot mopped felts.

• 6-mil-plus polyvinyl chloride (PVC).

• 40-mil polymer modified asphalt.

• 6-mil polyethylene.

The waterproofing should be applied a minimum of 12 inches above the highest point of the ground water table. The membrane joints shall be lapped in accordance with the membrane manufacturer’s latest printed requirements.