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Sika Sarnafil helps realise architect’s ‘tree canopy’ roof

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School celebrates its 150th anniversary with a new sports hall, with a free-form glulam roof as its standout feature.

sika sarnafil st george

A new sports facility, featuring a Sika Sarnafil single ply membrane roof, has just been completed at St. George’s Weybridge, a Roman Catholic co-educational nursery, private day school and 6th form college in Surrey.

The new architectural development has been built as part of the school’s 150th anniversary celebrations and includes the transformation of an existing, functionally-simple sports hall, into a beautifully-designed facility that has a tree canopy-like roof structure draping over the building’s internal spaces.

Designed by global architectural practice Scott Brownrigg, the roof needed to achieve 30 m clear spans across the main hall and the design needed to be clever and sensitive to the fact that the site’s location sits within the green belt. It also required a flexible and durable waterproofing solution to ensure the building leaves a lasting legacy for future generations of Georgians.

Felicity Meares, Architect at Scott Brownrigg, comments on how they approached the design and specification: “We designed a bespoke freeform glulam roof that curves in multiple directions. Computer modelling software allowed us to create and control this complex roof form in virtual reality, pushing and pulling it to blend into the landscape.

In need of a roofing product elegant and pliable enough to accommodate the complex design, lightweight enough to minimise the impact on the roof’s structure and cost effective enough to cover such a large area, Sarnafil G410-ELF lead grey single-ply membrane was specified, along with Sarnavap 5000, 120 m SarnaTherm G insultation board and Sika SolarMount-1. Sarnafil adhered décor profiles were also built, allowing rainfall to be interrupted and guided across the roof.

Sarnafil worked closely with the architects and contractors to develop a specification that not only had the correct U-value, but was also compatible with the Cross Laminated Timber roof build-up and ancillary roof mounted systems used, such as Photovoltaics, Latchways, a built-in gutter and upstands for roof openings.

Roofing contractor Malone Roofing was tasked with realising the architect’s roof design. With both Malone and Scott Brownrigg having specified Sarnafil in the past, the entire team were confident that Sarnafil single ply was the right fit for this unique roof form.

Paul Hughes, Managing Director at Malone Roofing, oversaw the project. He comments on the project: “We started work on the roof in October 2018 and spent a combined total of twelve weeks on the project. Despite being faced with a particularly rainy period and a challenging design, with curves sloping up to 30 degrees in some areas, we were able to complete the roof on time and to budget.

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