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11.10.4 Granular and metal face surfacings on membranes should be checked for quantity and adhesion to the membrane.
11.10.5 Curling or wrinkling of organic felts may indicate decay of the membrane. "Picture framing" of the membrane above roof insulation
generally indicates the absorption of moisture by the insulation due to the effects of condensation. It can also indicate inadequately attached
roof insulation. The membrane should be checked for "fishmouths", "mole runs" and open laps.
11.10.6 Occasional blistering of the membrane normally indicates a minor error in application that can be easily repaired. Severe blistering
throughout the roof area, however, is a clear indication of major problems. Blistering on a large scale would indicate installation of wet
materials during construction, or it may be an indication that the membrane substrate is laden with moisture. The moisture may also be a result
of roof leaks or improper vapor retarder design. Care should be taken to determine the exact cause of the blistering so that it may be
eliminated in the reroofing construction.
11.10.7 Roof splits are normally a result of differential movement between building components. Areas which exhibit the greatest tendencies
for differential movement should be examined from the roof side to determine if the membrane has split. Some of these are:
- Over building expansion joints
- Over seismic openings
- Along the line of building additions
- The point at which deck types change (e.g., concrete to steel)
- The point at which deck panels change direction
- The smaller dimension of roof offsets (L, T, U shapes)
- Large expanses of roof area (dimensions greater than 200 ft. [61 m])
11.10.8 Differential movement must be accommodated if a new membrane is to have any chance of success.
11.11 Equipment and Accessories
11.11.1 After a thorough inspection of the roof perimeter and the field of the roof, all rooftop-mounted equipment should be carefully examined.
Equipment that has been added after the original construction and not properly flashed is a common source of roof leaks. Areas where
equipment has been removed and the roof not properly sealed is also a common source of water entry. Sheet metal coverings for HVAC units
and other rooftop equipment should be closely checked for holes and missing or improperly fitted panels. Many "roof leaks" have been traced
to improperly installed or deteriorated rooftop equipment. Equipment that contains refrigeration units or electrical motors should be checked to
ensure that oil or grease is not being deposited on the membrane.
11.11.2 Roof drains should be checked to see that they are open and properly flashed. Clamping rings must be tight and seals in place. The
seal between the roof drain and the plumbing system should be checked to ensure that it is watertight. Improperly flashed or stripped
expansion joint covers can be an easy route for water entry. Joints between individual shop-made sheet metal covers and factory-made covers
with integral bellows should be inspected. Since many of these expansion joint covers are raised above the roof level, they can easily suffer
damage when equipment is dragged or rolled across them. The basic material of the metal flange and bellows should be inspected for
material deterioration. The termination of expansion joint covers at roof edges, or parapet walls, should be checked to ensure that the
transition plane is watertight.
11.12 Roof Cuts
11.12.1 While roof cuts are not generally recommended in newly constructed roofing systems, they are very valuable and, in fact, essential in a
comprehensive evaluation of an existing roof system. Roof cuts allow the inspector to verify the exact construction of the roofing system. Roof
cuts also allow the inspector to determine, beyond a shadow of a doubt, if the roofing system contains any moisture at the point of the roof cut.
Roof cuts are valuable in further assessing the condition of the top surface of the roof deck. When roof cuts are to be used to determine the
construction of the roof membrane, they should be 6" x 45" (152 mm x 1143 mm) in size and cut at a right angle to the laps of the membrane.
This method of sampling is more meaningful than small square cuts because they reveal whether a base felt (if used) was properly lapped, and
if the ply felts were installed with the proper exposure. The frequency of the roof cuts may vary greatly, depending upon the size and the
condition of the existing roof. At least one roof cut should be made in each distinct roof area. Any area which is thought to have wet insulation
or wet deck material should be sampled. If moisture is found, sampling should continue at relatively close intervals, so that the limit of moisture
intrusion can be defined. For this type of sampling, a small "core sampler" of about 2" (51 mm) in diameter is preferred. Regardless of the
type of roof cut taken, great care should be exercised to ensure that these areas are properly repaired. Improper repair of test cuts can only
lead to further deterioration of the existing roofing system.
11.13 Non-Destructive Testing
11.13.1 Over the last decade, several methods of non-destructive moisture detection have been developed and refined. Properly done, and
verified through core sampling, they provide the decision maker with an accurate analysis of the degree of moisture infiltration into an existing
roof system. These systems have the advantage of not actually penetrating the roofing system, and thereby weakening it. None of these
systems, however, actually detect moisture.
