Generally, three categories of roofing problems are responsible for most failures: Design, materials, and workmanship. Here are some tips on proactively attacking these issueA well-designed roof of any system type will effectively repel water and other weather elements, but problems certainly do occur, especially as time goes by. Most problems can be traced back to these three categories: design, materials, and workmanship.
Design.
A large percentage of leaks in relatively young roofs (less than five years old) can be attributed to errors in the overall system design. The use of "boilerplate" specifications and designs not customized to the specific facility is prevalent in new construction and reconstruction projects, and using un-optimized specs often leads to underperforming roof systems. Generic designs do not take into account details that need to be customized to the specific system like insulation tapering requirements, structural deck requirements, insulation fastening pattern requirements, seam detailing, flashing and termination requirements, and backup waterproofing. Failure to design these critical details properly can lead not only to leaks but total system failure.
Materials.
Material failures are often found to be the culprit behind roof system problems. These failures can be caused by incompatible components, substandard supplies, or product failures. While many different types of materials can fail, one problem seen all too often is the use of substandard sealants.
Low-grade sealants, improperly applied on critical roof details like penetrations and terminations, can crack and fail in as little as three to five years, opening a building up to water ingress. Using properly rated and tested materials is always recommended for the longevity of a building. Using new, unproven products puts facility managers at risk for material failure. New product failures (like phenolic foam insulation and first-generation PVC and TPO) illustrate the need to use only proven roofing materials to reduce risk. Do not use your facility as the manufacturer's "test dummy." Industry experts recommend a minimum of 10 years of proven product performance in the marketplace before trusting a product with your building.
Workmanship.
It is possible to have a well-crafted design and the best possible materials and still have a failed project. If the construction is not properly executed, shortcuts, oversights, omissions, and overall poor workmanship by the contractor will lead to major and expensive issues down the road.
One of the biggest workmanship flaws frequently seen is installing wet insulation. This will create major leaks and accelerate the deterioration of the entire system. Bitumen, adhesives, and other components such as roof deck and fasteners will all break down prematurely in the presence of wet insulation. Neither single-ply nor built-up roof systems are immune to trapped moisture. Whether the insulation gets wet throughout the construction process or arrives on-site wet, it should never be installed in that condition.
Other common workmanship issues include incomplete vertical terminations of the roof-to-wall flashings, missing sealant at penetration flashings, incomplete coping details, short flashing height, missing drain strainers, and missing sealant around patches. Having a process in place for accountability and oversight will ensure the design is followed and the specified materials are utilized properly.
