Milbank Concrete Products describe how a precast concrete stair design provided a practical as well as unique result, for a high-end conversion of an Art Deco cinema
The Denham Film Studios are a collection of 224 conversion and new build homes in Buckinghamshire, including 154 one, two and three-bedroom apartments and 70 four and five-bedroom family townhouses. Features within the new development include a restored historic cinema with a bar and a community hall/fitness space. The new properties are designed around garden squares, landscaped grounds, rill water features, private gardens and protected woodland.
The Studios were opened by film producer Alexander Korda in 1936 and saw the filming of big screen classics like Brief Encounter. The main Grade 2 listed building has been converted into 49 apartments, around two new green squares and communal gardens, bordered by three new four-storey apartment buildings providing 105 new homes. Around the eastern side of the site there are avenues of new three- and four-storey terraced housing, and to the northern section two- and three-storey detached townhouses; all overlooking communal landscaping and private gardens.
The retained cinema – which was used to screen movies to Hollywood directors including Stanley Kubrick, Albert ‘Cubby’ Broccoli and Steven Spielberg – was refurbished and turned into a cinema theatre and club for residents; retaining an important link to the history of the site.
Sat within the heart of the apartment complex stands a duo of twisting precast concrete stairs with cast concrete handrails. Finished with LED lighting and Italian marble, they are thought to be the first of their kind in the United Kingdom.
Unique for offsite
The two precast concrete helical staircases that Weston Homes asked us to provide would need to incorporate 150 mm wide by 900 mm high concrete handrails, to tie in with the Art Deco style balustrading to the circulation areas of their flagship development site.
Constructing these flights using traditional insitu pouring methods would have proved to be challenging in terms of generating the flowing soffit and erecting the necessary formwork – this would have needed to remain in place for at least four weeks after the second flight had been cast. Instead, precast concrete’s quality, affordability, and longevity resulted in a well-designed, manufactured and installed finished product.
A staircase with a built-in handrail of this size has to our knowledge never been made offsite in a factory environment, and was a real technical challenge to not only structurally design but to also tie in with the building’s design. There were also restrictions on transport to the site and considerations on how they would be lifted into position due to the sheer size and weight of each individual flight – a staggering 22 plus tonnes between them. Although immensely challenging, we were completely satisfied with the final result, thanks to the effort put in by the team.
Design, construction and logistics
Kallisto have a long history of providing high-quality precast concrete solutions for the construction industry, and our experience and reputation led to us being chosen by Weston Homes for this unique and exciting renovation project.
The required soffit was able to be produced using our adjustable pallet moulding system, which also acted as the formwork for each storey height flight. Projecting starter bars were cast into the treads of the stair for tying into the precast wall reinforcement. The formwork for the walls was then erected on the flights and extensively propped prior to the concrete pour.
Utilising precast concrete constructed in an offsite environment has proven to be a beneficial alternative over traditional insitu methods of casting when taking overall end quality, cost-effectiveness, efficiency and safety into consideration.
Our precast components are manufactured offsite in an enclosed casting environment, avoiding delays due to inclement weather conditions. They are developed to be extremely structurally efficient, and supplied to an exact build fit and specification, accelerating the build process. Insitu moulds generally need to be left in place for weeks to allow the concrete to cast.
Precast components allow immediate site and finishing access following installation, providing a safe and solid footing and reducing delays for follow on trades. Components can also be delivered to site as required in the build process ensuring that onsite storage is not an issue when space is at a premium.
In this case, the two four metre diameter staircase flights each weighing over 11 tonnes, were delivered to site on a specialist low loader accompanied by a support vehicle. They were also installed in one day by one of our professional fixing teams, minimising disruption on site and providing an immediate access to the upper levels for other trades.