Design Problems

Design-related problems are expensive to correct, and normally the corrections must be done while the replacement of the roofing material is undergoing.  Some examples are:

• The weak structure supporting the roof that might deflect excessively under active loads

• Improper roof slope, sagging roof, or inadequate drainage system, resulting in accumulation of water

• Incorrect system to allow expansion and contraction of changes in deck material or changes in direction

• Incompatible roof materials

Wind

The vacuum and the uplifting pressure created by wind, blowing over the edge of the roof, can partially rip the roofing membrane or system that has been applied.  To counteract the forces that are exerted on the roof, the roofing and insulation must be fastened and secured to the perimeter and the main roof structure.

The function of the flashing is to provide a seal, a watertight seal, between roofing materials, roof sections, and other parts of the building. It is an area that should be carefully inspected prior to any other area. Incorrect installation procedure or attachment, and improper sealing of the flashing will allow the water to enter between the roofing systems and the roof structure. Sometimes, installing a flashing over a joint or cap will eliminate the problem if it is detected early in the construction.

Either small or large penetration flashing can fail in several ways.  As a matter of example:

• Improper design

• Broken seams in metal curbs due to building movement

• Deteriorated counter flashing

• Improper finishing of metal surfaces

• Standing water behind penetration curbs

Drain Flashing

It is not as simple as installing lots of drain openings.  The building’s drain system should consist of reasonable drain openings, an adequate pitch from high point to drainage components.  It is a good practice to include overflow scuppers through different areas to avoid the accumulation of water in case of an emergency.  Proper maintenance should be given to all of these areas.

It is very easy to install the A/C compressor, the satellite antenna, and other components directly to the surface.  Proper attention should be given when this kind of equipment is installed.  They should never be mounted or placed directly to the top of the roof membrane.  They should be mounted to a support structure or raised curb-type supports.  Flat flange or curb flashing can then be used to keep the roof watertight, and roof replacement and recovery can be done without disturbing or removing the equipment.