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Oklahoma Administrative Code (Last Updated: March 11, 2021) |
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TITLE 748. Oklahoma Uniform Building Code Commission |
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Chapter 20. Adopted Codes |
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Subchapter 15. IPC® 2015 |
SECTION 748:20-15-16. IPC® 2015 Chapter 11 Storm Drainage
Latest version.
- (1) Section 1101.7 Roof design. This section has been modified to change the section number for the requirement to accommodate the design rate for secondary roof drainage from Section 1106 to Section 1108. This section has been modified to read: 1101.7 Roof design. Roofs shall be designed for the maximum possible depth of water that will pond thereon as determined by the relative levels of roof deck and overflow weirs, scuppers, edges or serviceable drains in combination with the deflected structural elements. In determining the maximum possible depth of water, all primary roof drainage means shall be assumed to be blocked. The maximum possible depth of water on the roof shall include the height of the water required above the inlet of the secondary roof drainage means to achieve the required flow rate of secondary drainage means to accommodate the design rainfall rate as required by Section 1108.(2) Table 1108.1 Size of secondary scuppers for a 10.2-inch per hour rate of rainfall. This table has been added to the code to provide sizing for secondary scuppers for a 10.2-inch per hour rate of rainfall. The Table shall read as: Table 1108.1 Size of Secondary Scuppers for a 10.2-inch per hour rate of rainfall. A table has been inserted with two columns, both with four rows beneath. The first column title is "Head in inches" and the second column title is "Horizontally Projected Roof Area (square feet) Length of Weir in inches". The second column should have seven sub-columns labeled 4, 6, 8, 12, 16, 20 and 24.(A) Below is the "Head in inches" column with the corresponding "Length of Weir in inches" for each of the sub-columns:(i) Row 1. Head in inches column is 1, sub-column 4 is 112, sub-column 6 is 169, sub-column 8 is 226, sub-column 12 is 339, sub-column 16 is 452, sub-column 20 is 565, and sub-column 24 is 678.(ii) Row 2. Head in inches column is 2, sub-column 4 is 314, sub-column 6 is 471, sub-column 8 is 628, sub-column 12 is 942, sub-column 16 is 1256, sub-column 20 is 1571, and sub-column 24 is 1885.(iii) Row 3. Head in inches column is 3, sub-column 4 is 565, sub-column 6 is 848, sub-column 8 is 1130, sub-column 12 is 1696, sub-column 16 is 2262, sub-column 20 is 2828, and sub-column 24 is 3393.(iv) Row 4. Head in inches column is 4, sub-column 4 is 879, sub-column 6 is 1319, sub-column 8 is 1759, sub-column 12 is 2637, sub-column 16 is 3519, sub-column 20 is 4399, and sub-column 24 is 5279.(B) Beneath the column the following should be added: For SI: 1 inch equals 25.4 mm. Notes:(i) To adjust this table for other than a 10.2-inch design rain fall rate multiply the square footage on the table by 10.2 then divide by the design rainfall rate.(ii) This table does not apply to scuppers with a vertical opening height that is less than the head height. Example: For 4 inches of design rainfall rate, a 4-inch long scupper with a 1-inch head would accommodate 286 square feet. (112 times 10.2) divided by 4 equals 286.(3) Section 1108.3 Sizing of secondary drains. This section has been modified to include the use of scuppers or increase the sizing of secondary drains to accommodate rainfalls of 10.2 inches per hour and includes minimum design loads. This section has been modified to read: 1108.3 Sizing of secondary drains. Secondary (emergency) roof drain systems or scuppers shall be sized in accordance with Section 1108 based on a rainfall rate of 10.2 inches per hour. In sizing secondary roof drain systems using Tables 1106.2, 1106.3 and 1106.6, the Horizontally Projected Roof Area shall be determined by dividing the Horizontally Projected Roof Area for 1-inch rain fall per hour rate by 10.2 inches per hour. Scuppers shall be sized to prevent the depth of ponding water from exceeding that for which the roof was designed as determined by Section 1101.7. Scuppers shall not have an opening dimension of less than 4 inches (102 mm). The flow through the primary system shall not be considered when sizing the secondary roof drain system or scuppers. Scuppers shall be sized in accordance with Table 1108.1 or by other national methods using the head height of water and flow rate of the scupper.