2009 International Residential Code
R903.2 Flashing. Flashings shall be installed in a manner that
prevents moisture from entering the wall and roof through
joints in copings, through moisture permeable materials and at
intersections with parapet walls and other penetrations through
the roof plane.
**Commentary: **As with flashing required for other locations at the
building’s exterior, it is critical that those locations
where moisture may penetrate the exterior membrane
at the roof be adequately protected. General locations
identified include joints at the coping, intersections
with parapet walls and other penetrations through the
R903.2.1 Locations. Flashings shall be installed at wall and roof
intersections, wherever there is a change in roof slope or direction
and around roof openings. Where flashing is of metal, the metal
shall be corrosion resistant with a thickness of not less than 0.019
inch (0.5 mm) (No. 26 galvanized sheet).
**Commentary: **This section identifies specific roof locations for the installation
of flashings. In those cases where metal is
used as the flashing material, it must be corrosion resistant
and a minimum No. 26 galvanized sheet.