4.1.6.7.Areas Adjacent to Roof Projections

(1) Except as provided in Sentences (2) and (3), the accumulation factor, C a, for areas adjacent to roof-mounted vertical
     projections shall be calculated in accordance with Sentence 4.1.6.5.(1) using the following values for the peak
     accumulation factor, Ca0, and the drift length, xd:
     (a) Ca0 shall be taken as the lesser of,

                                                        γh         γl0
                                                0.67         and          + 1, and
                                                       Cb Ss     7.5Cb Ss

     (b) xd shall be taken as the lesser of 3.35h and (2/3)l0, where h = height of the projection, and l0 = longest horizontal
         dimension of the projection. (See Note A-4.1.6.7.(1))

     (2) Ca is permitted to be calculated in accordance with Article 4.1.6.5. for larger projections. (See Note A-4.1.6.7.(2))

     (3) Where the longest horizontal dimension of the roof projection, l0, is less than 3 m, the drift surcharge adjacent to the
     projection need not be considered.

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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.