Roofing failure audit or forensics is an emerging specialized service, which is part of a façade audit that does a diagnosis of the design at a micro level. The purpose of this service is to identify the weak links in the roofing design and implementation before a disaster can destroy the building envelop and endanger lives of occupants and of people near the building.

By Ar. Harish Gupta

Roofing Failure
Figure 1: Roof failure due to stress

A roofing that is connected to the vertical elevation of the building is like a continuous façade that covers all the exposed sides of the building. Roofing elements like the skylight are made of similar façade elements like aluminum and steel structure, with choice of weather-proof coverings like glass, polycarbonate, tensile fabric, and other innovative materials that are flooding the market.

Only experts can understand the micro details of doing a very good roofing design and execution. Audit can be conducted at various stages. When the concept and design has been finalized, an audit of the budgeted cost and the detailed design will bring to surface the actual cost of the roof by breaking up every component and activity into a cost structure along with design review.

Once subcontractors have been appointed and have produced design drawings, calculations and thermal models, a full technical design audit will be completed by the audit team of the contractor’s designs. The audit consultant will undertake drawing-specific reviews, checking to help see that the relative designs conform to the specification and the client’s requirements, and that the design meets all the technical, lifetime and performance requirements of the project.

At this stage, it’s not only the roof design that gets reviewed but also the suitability and adaptability of the sub structure. This will be a very handy tool for decision makers when they invite quotes, and also in understanding the intricate details of the façade to make an informed decision. Quite often, decision makers are not clear of the minute details in an envelope design as it is an extremely complex, tailormade solution. Squeezing the cost to fit the budget leads to compromising on the quality, that goes unchecked till disaster strikes. Audit of design and cost at the pre-finalization stage will help alter the design in a manner that will not compromise the safety and integrity of the design, and will offer a correction to the budgeted cost.

Roof failure due to stress

roofing failure
Figure 2: Roof blowout due to inadequacy of structural strength
The other stage of audit is post completion when the building is fully functional and perhaps a few years into service when problems start to surface. Fig 1 demonstrate the type of problem that occurs in a building that did not have a systematic audit conducted. That is the time when forensics comes into the picture to identify the root cause of the roof or envelope failure and provide solutions to rectify the defect.

Roof failures are not just limited to collapse, cracks, or excessive water or air infiltration. Building envelopes that do not comply with project specifications, governing building codes, or industry standards have also failed. Considering the complexity of contemporary roof systems, understanding why they fail to perform as expected is seldom an easy task. Failures can originate from a wide variety of influences; such as accumulated differential thermal or moisture expansion, inadequate wall cavity drainage, or material incompatibility Complicated internal leak control systems or intricate connection or support mechanisms further increase the probability of roof failures. Special diagnostic techniques and tools are needed to properly identify the failures to enable effective remedies.

Roof blowout due to inadequacy of structural strength

Harish Gupta
When the envelope fails, it’s important to have an understanding of how the system works so you can consider what could have gone wrong. A basic knowledge of components and properties can help you lay the necessary groundwork and map the crime scene.

Equipped with this basic understanding of envelope science, you’ll be able to take your knowledge into the field and prevent possible failures.

Architect & Engineer Harish Gupta is a Facade Consultant with more than 25 years of experience. He can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it.

MGS Architecture May 2018