Intent 1:
To exempt situations from the application of Sentence 9.26.4.8.(1) where sufficient protection is provided by flashing
and counter flashing.
Intent 2:
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, or
- compromised thermal performance of components intended
to provide resistance to heat transfer.
This is to limit the probability of:
- an inadequate control of relative humidity, temperatures
of interior spaces or water accumulation,
- the generation of pollutants from biological growth
or from materials that become unstable on wetting, or
- deterioration, which could lead to compromised integrity
of roofs or assemblies protected by roofs.
This is to limit the probability of:
- negative effects on the air quality of indoor spaces,
- the inadequate thermal comfort of persons, and
- contact with moisture.
This is to limit the probability of harm to persons.