Clifford's Tower


Non-slip timber decking used to construct roof deck at historic Clifford’s Tower in York

All in the detail

Perched on a hill overlooking York, Clifford's Tower has played a significant role in the city's history. And now, following a £5m refurbishment project, which included the construction of a roof deck using Marley CitiDeck, this historic monument can continue to delight and educate visitors for many more years.

A fortress has stood on the site of Clifford's Tower since the Norman Conquest and the structure has served a number of functions throughout its history, from a royal mint to a medieval stronghold and a garrison in the Civil Wars.

Until very recently, the remains of the English Heritage structure were little more than a hollowed-out shell. But the refurbishment project has brought life – and tourists – back to the bastion, opening up parts of the tower that have been off-limits since the tower was gutted by fire in 1684.

The works have included installing aerial walkways that provide access to the first-floor rooms of the tower, while a free-standing roof deck provides spectacular 360-degree views across York. To help ensure the safety of visitors, and to provide a natural and attractive surface, Marley’s non-slip timber decking, CitiDeck, was used for the decking.



  • Citideck®


  • Heritage


  • Hugh Broughton Architects Ltd


  • York


  • Retail and Leisure Project of the Year & Winner of Winners at structural Timber Awards 2022

  • Preservative Treated Wood Project of the Year at the 2022 WPA awards

Note: All of our decking products now use a new treatment which changes their colour to a French Beige - Tobacco Brown. While the colour has changed, the case studies still serve as a good indicator for the shape, function and possible applications of the product range. To see the new colour, please visit the main decking page or request a product sample.

Cliffords Tower using Marley Citideck Cliffords Tower using Marley Citideck

Non-slip timber decking fit for a king

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.

Non-slip timber decking CitiDeck - A safe surface

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.

Sustainable non-slip timber decking

Sustainability was another important consideration. While a variety of decking products were considered, including composite boards. Timber was ultimately chosen due to its sustainability credentials.

“Timber was preferable due to it being a natural material,” the architect explains. Marley’s CitiDeck is sourced from managed forests that are PEFC certified, so specifiers can rest assured that it is an environmentally friendly product. The architect also notes that timber has the potential for repurposing at the end of its lifespan: “There are more options for recycling the boards at the end of their usable life,”.

Specifying Marley CitiDeck

As well as providing a durable, slip-resistant and attractive decking product, Marley also helped to ensure the Clifford’s Tower project went smoothly, answering questions and queries as they came up, providing details in terms of product selection and composition.

To find out more about Marley’s range of anti-slip timber decking products, including CitiDeck and AntiSlip Plus, please browse our product pages. You can also get in touch to discuss your project with a member of our team or order a sample to see the quality for yourself. 
Cliffords Tower using Marley Citideck
Cliffords Tower winner of WPA awards 2022

We're very excited to announce that Clifford's Tower won Preservative Treated Wood Project of the Year at the 2022 WPA awards!