NEED
FOR
INSPECTION |
It is a known fact that 90% of occurring
leaks originate at or along perimeter
and projection flashings. By setting
up a regular program to identify these
problem areas and correct them, leaks,
interior water damage, and roof system
deterioration can be cut to a minimum.
|
EQUIPMENT
REQUIRED |
The most important tool to use while
inspecting your flashing system at the
gravel roof line is a wire brush. All
too often areas are overlooked because
they are hidden by the gravel. Make
notes of problem roof flashing areas
and match these to known interior leaks.
|
METAL
EDGE
INSPECTION |
Begin the inspection by walking the
perimeter of each roof, making notes
of obvious problem areas. If the roof
system has metal edge gravel stops,
at each joint in the metal brush away
the gravel and look for splits. Along
the roof side of the metal edge in approximately
6"-8" areas, look for slight
depressions or ridging, again brushing
away the gravel. Due to the high degree
of expansion and contraction of the
metal, it can and does saw through the
flashing and allows water to enter.
|
BASE
FLASHING
INSPECTION |
Base flashing, since it extends upwards
past the gravel line, is easily overlooked.
Cracks, holes and splits in the vertical
section are quickly identified. However,
using the wire brush, approximately
8" out on the horizontal, brush
back the gravel and look for openings
where the flashing terminates on the
roof mat. Look for splits, cracks and
pinholes at the toe of the cant. These
are all indications that the flashing
is starting to absorb water at the gravel
line.
|
PROJECTION
FLASHING |
Basically there are two main types
of flashings - vertical flashing and
horizontal flashing. Inspect both carefully
using the wire brush, for these are
problem areas due to equipment vibration
and differential movements.
|
METHOD
OF
CORRECTION |
If hot bitumen was used in applying
the roof mat and flashing system, why
not repair using hot bitumen? There
are three reasons. First, in most cases,
the vertical portion of the felt flashing
was installed using asphalt mastic.
Second, hot bitumen solidifies and becomes
somewhat brittle upon cooling, and cannot
withstand high degrees of movement,
thereby allowing splits in the bitumen
at the metal edge joints and flanges
as discussed earlier. Third, hot bitumen
contains no solvents and adheres by
heat. Too cool and there is no adhesion;
too hot and there is no build. For these
reasons, repairs are best made using
soft-setting asphalt mastic in conjunction
with a membrane for tremendous strength
and movement capabilities.
|
METHOD
OF
PROTECTION |
All too often, good repairs are wasted
or short term due to the lack of protection.
At the horizontal, have the contractor
replace the aggregate over all exposed
repair areas. At all vertical flashings,
apply either an asphalt aluminum cut-back
or a white acrylic coating.
This will block out the ultraviolet
rays of the sun and the life of your
roof flashing system will be long-term
(10 years) instead of short-term (3
to 5 years).
|
IMPORTANT
INSPECTION
POINTS |
When inspecting your built-up roof
flashings, look for the following:
A 45° angle or cant must be existing
at all horizontal and vertical points
or the roof will split at this point
and allow water entry.
- Where built-up roof and metal meet, the difference of expansion and contraction of the two dissimilar materials creates splits/leaks and allows water entry.
- Check all perimeter and projection flashings carefully - 80-90% of a roof's problems originate at these points.
- When inspecting your roof's metal edge, brush back the gravel at each metal edge joint and look for splits in the flashing at this point.
- All vertical flashings must have ultraviolet rays of the sun blocked out or they will rapidly dry out and begin to deteriorate.
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