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By: Adam McManus

A warranty for a new low slope roof system typically covers a properly designed and installed roof system that develops a leak due to contractor workmanship or a manufacturing defect.  There are two types of warra

nties that may accompany a new roof system, the contractor’s warranty and the manufacturer’s warranty. Within the first 2 to 5 years, the contractor is typically responsible for the craftsmanship;

it is believed by many industry professionals that a craftsmanship deficiency will emerge within the first few years after installation. The manufacturer’s warranty covers the manufacturing defects for 10 to 25 years, depending on the design and material. Some warranties are prorated and others have a no-dollar-limit, meaning that the full price of the system or membrane replacement is covered by the manufacturer in the event that the material fails prematurely within the set time period. Either one of these two warranties has exceptions known as “exclusions” that can render them void, including “Acts of God”, terrorist attacks, etc. Below are some examples of typical exclusions:


Acts of God

  • Lightning strikes
  • Fire
  • Acid rain/hail
  • Thermal shock
  • Hurricane, tornado, microburst
  • Wind blown debris
  • Volcanic activity

Impact from Humans/Animals

  • Impact on living organisms
  • Excessive pedestrian traffic
  • Unauthorized or improper repairs

Impact from Environment/Building Systems

  • Marine salt water
  • Steam/exhaust/hot water
  • Exposure to incompatible materials
  • Exposure to extreme temperatures
  • Accumulation of condensation from below roof system

A good roof design will go above and beyond required minimum building standards criteria and will help avoid pitfalls associated with the “exclusions” in typical manufacturer warranties. The best way to ensure quality control for a properly installed roof system is to have qualified monitoring during construction. The design criteria should meet the minimum building code requirements, be compatible with the local climate and be customized to the roof space usage. Furthermore, construction monitoring is used to verify the quality of work during roof construction.

A system that is suitable for a roof’s intended use will account for pedestrian traffic. Walkway pads can be installed to protect high traffic areas and help delineate the appropriate paths for movement over a roof surface. Technicians who access the roof to service heating and cooling units should have a path that takes them from egress points to each unit. An owner may establish rules for roof usage, and limit access, to keep the pedestrian impact to a minimum.

Climate and weather conditions should be factored in the roof design. If the building is prone to lightning strikes, a lightning protection system should be installed, especially if there is a need for computer equipment surge protection. According to the Underwriters Laboratory (UL), “A lightning protection system is defined as a complete system of strike termination devices, conductors, grounding electrodes, interconnecting conductors, surge protective devices, connectors or fittings.” 


Wind load design criteria can be a significant factor in the longevity of a roof system. A designer will ensure that the fastening system will meet the wind uplift.

In some habitats, migratory or indigenous fowl may be attracted to a roof space for nesting purposes. Bird protection systems often include deterrents such as spikes, electric wires, netting or electronic scare mechanisms.

Proper ventilation is a design factor that should correspond to the climate, type of structure and use. Condensation build-up in the interior of the building can affect the thermal value in the roof system and potentially increase utility costs and the likelihood of premature roof system failure.

Though we cannot control the impact of forces caused by “Acts of God”, preventative steps can be taken to shield the roof from humans, animals, the environment as well as the building system controls. A thorough design by a qualified engineer/architect can help address the pitfalls of warranty exclusions. The installation of a well-designed system by a qualified installer is paramount to achieving the designer’s intent. The implementation of a roof maintenance program can mitigate issues that stem from seasonal changes, as well as provide the owner a  useful checklist, for pro-actively identifying necessary repairs.

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About Sullivan Engineering, A Rimkus Company

Sullivan Engineering provides high-quality building envelope restoration and compliance solutions.

We partner with facilities managers and account executives to provide technical expertise and project management for building envelope restoration, compliance, and maintenance.

Our solutions reduce the overall building life cycle maintenance costs by creating long-lasting, high-quality work for years to come.