Sherwood, New Build Observatory, Nottinghamshire

Brief

The project sought to create a landmark building that would attract visitors to the region and support education in STEM-based subjects. Key objectives were to preserve the heritage value of the original Victorian reservoir building, complete with its distinctive brick arches, while also creating additional capacity and introducing key sustainability measures and accessibility features, including assistive technologies.

Part of the complex would be newly built over the old building, which dated back more than a century. Over 7 metres deep and with a diameter of 25 metres, it had essentially been unoccupied for decades. The design therefore needed to bring all the elements together into one seamless, functional site, and to ensure that modern standards of safety and sustainability were observed throughout.

To minimise environmental impact, carbon footprint and routine energy costs, the design included a green insulated roof, solar PV panels, energy-efficient lighting systems and modern glazing. Another key element of the plan included the use of an external wall insulation system below the observatory dome.

Design and Specification:

As part of the design and planning application process, Permarock technical staff conducted pull-out tests and provided digital visualisations and material samples in a range of colours. The sample boards, featuring the EWI system applied according to the specification, were retained on site throughout the contract for the purposes of inspection and comparison.

The chosen EWI system comprised:

• Permarock Mineral Fibre Insulation (dual density); and
• Permarock Silicone^Ultra K Finish (textured render).

When combined with Permarock Silicone^Ultra K finish, Permarock Mineral Fibre EWI systems achieve an A2-s1,d0 reaction to fire classification (EN 13501-1: 2018). This means that they may be installed on buildings of any height, including those with floor levels of 11 or more metres above ground level.

The Permarock Mineral Fibre Dual Density Insulation was supplied in boards measuring 1200 mm x 600 mm, and installed to a thickness of 250 mm. On all elevations, the insulation boards were affixed using both a cement-based adhesive and galvanised steel screws.

Permarock Silicone^Ultra K Finish is a lightweight textured render with a nominal 1.5 mm grain size. It is water repellent, vapour permeable and available in a wide range of colour-fast shades. On this scheme, white and other light colours were specified in order to minimise thermal gain during the summer months.

Permarock Silicone^Ultra K Finish features nano-quartz technology that helps to shed dirt through the normal actions of weathering. It also contains special preservatives that inhibit organic growth. Both features enable it to maintain a bright, unspoiled appearance without the need for frequent cleaning or maintenance. It exhibits a typical working life of over 30 years.

Permarock systems based on dual density mineral fibre insulation and Silicone^Ultra K Finish can be designed to achieve levels of hard- and soft-body impact resistance that satisfy the requirements for building facades (including the zones associated with Categories I, II and III as defined in ETAG004.)