INCA Case Study: HMS Owl, Scotland

Renovating a historic WWII air base has been a labour of love for the client. After a mammoth five-year restoration project, including a feature on Grand Designs, the next stage was bringing the building up to energy efficient building standards. The Category C-Listed property is now one of Scotland’s most remarkable homes.

The four-storey brick building was constructed in 1942 as a control tower for the Royal Navy airfield known as HMS Owl, a base for torpedo-carrying aircraft during WWII.

The main aim for the client was to lovingly-restore the wartime control tower into a cosy family home, by completely modernising the property, while keeping the spirit of the historic building, however energy efficiency had always been the top of their list from the start.

With this in mind, the client reached out to an energy efficient specialist to look at how they could bring the cold concrete building up to energy efficient standards. With the initial idea looking at Internal Wall Insulation, they quickly changed over to an external option, when they realised the property could keep the traditional brick features on the inside, while giving the exterior a facelift, and more importantly, vastly increasing the thermal efficiency of the building.

From this, Wetherby Building Systems Ltd were contacted to specify Wetherby Thin Coat Façade System as a suitable system for the unique building, with Briden Construction Group Ltd as the installers.

To help with increasing the energy efficiency of a very old and cold building exposed to the elements, Wetherby’s thermal system component, Enhanced EPS Insulation from S&B EPS was used in 90mm thickness. Enhanced EPS Insulation comprises of expanded beads of polystyrene that incorporate a graphite component, fused together in a pressurised steam-heated mould. The addition of graphite provides a significantly improved thermal insulation material. Wetherby Thin-Coat Silicone Render was used for the finish, offering superb quality, ease of application and a superior colour range.

The client had a vision for the whole building to be black, this meant that Wetherby needed to source specially made EWI beads and sills in the same colour, to provide the desired look. Trueline (Specialists in EWI Render Beads, Trims & Accessories) were able to offer bespoke colour matched profiles, as well as innovative design to suit the building and environment. Also offering swift delivery to the highlands site!

With the location of HMS Owl standing alone in the highlands, it also means the south and west is exposed greatly to the sun and likely that any dark products would retain heat. The clients chosen render colour was black (RAL 9005 colour code) for the building, which has a Light Reflectance Value (LRV) of 0. The lower the LRV in a colour, the more likely a product will absorb, which can be a cause for discolouration or cracking.

Luckily, Wetherby’s Thin- Coat Render finish already has a flexible anti-crack formulation and ultra- violet resistant pigments. To provide extra protection against the exposed elevations, a double layer of Wetherby Alkali Resistant Scrim Cloth (mesh) was specified for this project, to ensure the render finish stays intact. This was incorporated into the top third of the Wetherby K+A Scrim Adhesive to provide extra strength to the façade system.

HMS Owl is a 4-storey building, which is uncommon for a single dwelling. Due to the nature of the building (and again, location), wind-loading calculations were required to be undertaken to ensure the system would be suitable. These were then provided to Wetherby’s Technical Director to work out a suitable fixing pattern. Eventually this was then input into the specification for the installation.

The unrivalled versatility of Wetherby silicone thin coat render system allows the products to be specified with confidence to transform virtually any substrate, giving dull and tired looking structures a new lease of life. The previous u-value of the previous 215mm Brick Wall for HMS Owl was 2.00 W/(m²K), but has now dramatically been reduced to 0.30 W/(m²K), while showcasing a statement and contemporary exterior.