4.1.7.7.Internal Pressure Coefficient

(1) The internal pressure coefficient, Cpi, for buildings shall be as prescribed in Table 4.1.7.7.

   (2) The internal pressure coefficient, Cpi, for cladding on parapets shall be –0.70 to +0.70. (See Note A-4.1.7.7.(2))
                                                              Table 4.1.7.7.
                                                     Internal Pressure Coefficients
                                                   Forming Part of Sentence 4.1.7.7.(1)

                                      Building Openings                                                 Values for Cpi
 Uniformly distributed small openings amounting to less than 0.1% of the total surface area
 of the building                                                                                         –0.15 to 0.0
 Non-uniformly distributed openings of which none is significant or significant openings that
                                                                                                        –0.45 to +0.30
 are wind-resistant and closed during storms
 Large openings likely to remain open during storms                                                     –0.70 to +0.70

This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.

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Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.