Sheet metal flashing at the intersections of roofs sloping upwards from masonry chimneys that are not provided with a saddle, on buildings to which Part 9 applies [see Sentence 1.3.3.3.(1) of Division A for application of Part 9].

To exempt situations from the application of Sentence 9.26.4.8.(1) where sufficient protection is provided by flashing and counter flashing.

To limit the probability that the flow of water down a roof's surface will be interrupted by a wide chimney, which could lead to a temporary increase in water depth beyond the depth protected by roofing or by the vertical leg of flashing at the chimney, which could lead to precipitation or meltwater ingress, which could lead to damage to masonry or to chimney liners from freeze-thaw stresses, which could lead to the premature failure of chimney liners, which could lead to carbon monoxide gas leaking into living space, which could lead to the acute poisoning or asphyxiation of persons.