Figure 1 – Discoloration of ceiling finish reported to be storm-related. However, storm-created openings to the roof and exterior walls were not found. The shape of the discoloration from the joint is consistent with vapor rather than liquid water that would be
expected from wind-driven rain.
Figure 2 – The outer edge of this gutter is higher than the top of the exterior wall. In
this case, the downspouts were clogged with tennis balls (this was a tennis club), and
water flowed down the inside of the exterior wall of the building during a heavy rain.
ventilation equal to one square foot per
150 square feet of ceiling space—or half
of that, provided the ventilation is split
between the upper portion and eaves to
promote convection. Proper roof ventilation can be challenging enough with
a conventional attic space. The frequent
oversight comes into play with vaulted
and cathedral ceilings. There is no ‘attic’
to ventilate, but the code still requires
ventilation of the roof cavity between the
rafter and the ceiling.
During an assessment of storm-related
damage in the wake of Hurricane Ike,
a church with a cathedral ceiling and
tongue-and-groove ceiling finish had re-
portedly sustained storm-related distress
in the form of discoloration to the interior
ceiling finish (Figure 1). After inspection
of the roof and exterior wall assembly it
quickly became apparent that the property
was devoid of storm-created openings.
The roof was also not equipped with ridge
or soffit vents. Warm humid air becomes
trapped within the assembly, gets heated,
expands, and escapes between the joints of
the ceiling finish. Overtime this hot water
vapor causes discoloration of the finishes.