Building the roof deck required careful planning, both to preserve the historic structure and to ensure the new elements were structurally sound. This meant building a completely new timber structure inside the tower.
Four enormous glulam columns were installed to provide support for the timber deck. They also form the basis for the internal walkways and staircases that provide access to the upper levels of the tower.
The non-slip timber deck itself was constructed using Marley CitiDeck. The decking was installed, and carefully cut to a smooth curve following the line of the new metalwork guarding at the edge. There is also a large opening in the middle that allows visitors to look down to the floor of the keep. The boards were also used to create seating areas and the guard structure around the central opening.
“We chose CitiDeck because we needed an attractive and robust anti-slip timber decking for use in high-traffic public areas,” explains an architect at Hugh Broughton Architects Ltd who worked on the project. “We wanted a consistent appearance between the deck boards, and the timber boards forming the sides to the benches and perimeter guarding, and CitiDeck made that possible,” they add.
With high numbers of visitors to the tower, safety was a top priority. “It’s great that CitiDeck boards perform very well in testing when both wet and dry,” the architect says.
According to the Health and Safety Executive, flooring is considered to have a low slip potential if it achieves pendulum test value (PTV) of at least 36. CitiDeck has been extensively tested, and has far exceeded the minimum, with PTVs of 61 when wet and 73 when dry.
Durability and ease of maintenance were also important considerations for the external and exposed public rooftop area. The smooth profile of the boards was an especially attractive feature, as it reduces the likelihood of grit getting trapped in any grooves. It also means that the decking can be easily cleaned by brushing, as there’s no water source available at the roof deck level.