A Guide to Flat Roof Refurbishment

James Wilkinson from Gradient Design provides a guide to flat roof refurbishment.

AGE, POOR MAINTAINENCE, AND DECK DEFLECTION are among the many causes of roofing failure. When this happens, urgent action is required to prevent costly damage to the building itself. Therefore, which factors need to be taken into consideration when undertaking the refurbishment of an existing flat roof system?

With climate change leading to an increase in extreme weather systems, which have seen four of the UK’s wettest winters take place over a 14-year period since 2006, it focuses the need to ensure a building’s most protective element is correctly designed and installed in order to optimise its long-term performance.

Eliminate Ponding

Aside from the visual signs of failure, indications that a roof isn’t performing as it should include rooms within a building feeling too cold in winter or excessively warm in summer. Poor roof performance can also contribute to acoustic problems, particularly in commercial buildings and schools. Sound transmission between floors and external noise penetration often worsen when roof insulation fails. Addressing these issues during refurbishment presents an opportunity to improve both thermal and acoustic performance. Solutions such as acoustic ceiling tile systems installed beneath the roof deck help manage sound whilst complementing upgraded insulation. This integrated approach tackles multiple building performance issues simultaneously, providing better value from refurbishment projects.

When it comes to a flat roof’s refurbishment, an initial survey is carried out to assess its condition. This will determine what action needs to be taken to ensure it meets industry regulations for energy performance. It will also help achieve the required falls outcome, which is crucial to directing water away from a roof and preventing ponding.

A flat roof is typically designed to shed water, not collect it. Failure to address this basic element of a roof’s design could ultimately lead to system failure and structural deflection due to the weight of water collecting on the roof.

Designing for Falls

In terms of falls, there are several types of tapered designs which ensure water is effectively dispersed from the roof, the most common being fully-mitred, and straight falls to tapered gutters. “Flat roofs are not flat”, as the saying goes, so in order to eradicate ponding issues, falls on a flat roof should achieve a minimum 1:80 pitch at any point.

Gradient is able to manufacture a system that achieves these falls but still meets regulation thermal performance. This is due to its ability to offer a bespoke tapered insulation system that is designed to overcome the backfall in order to prevent water ponding.

Survey Calculation

For larger refurbishment projects such as those involving schools, surveys are even more of a necessity. It allows Gradient, for example, to plot where ponding-based deflections have occurred and allow them to design-out future issues by calculating how to achieve constant water movement over a roof, rather than have it disperse and build-up in different areas.

Ask the Expert

Ideally, a non-leaking flat roof can be refurbished simply by bonding a new tapered insulation system direct to the existing felt substrate. Again, this is where engaging with a specialist such as Gradient pays dividends, as its teams are not only able to design and manufacture a solution to a client’s precise requirements, the completed system can be transported in its entirety to ensure a time and cost-effective installation that will last the lifespan of the building.

Roof refurbishment isn’t a game of chance; one errant episode in the design or installation process can cost the building’s owner dear in the long-term. Which is why its overall maintenance is best left to the experts; because peace of mind is priceless. 

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