Chester Zoo Lodges

Synopsis

The Reserve is a new lodge development at Chester Zoo comprising 53 guest lodges and a central welcome and hospitality building. Safeseal Roofing Ltd was appointed by Starship Group to deliver the full green roof package as part of their build programme, consisting of a vapour control layer, PIR thermal insulation and Bauderflex waterproofing system, finished with a pre-grown sedum blanket.

Bauder building board

The specification

The client required a reliable, fully watertight roofing system capable of supporting a living sedum blanket while blending naturally into the surrounding landscape. The design brief focused on sustainability, biodiversity and achieving a visually soft finish that complemented the setting of the new accommodation. To meet these requirements, the full Bauder specification was installed, including the vapour control layer, thermal insulation and Bauderflex waterproofing system, finished with a pre-grown sedum blanket.

Safeseal Roofing worked closely with Starship Group and Bauder’s technical team to ensure the specification was suitable for each lodge design and installed to the required standard. The project was delivered to programme and handed over in time for the opening of Chester Zoo’s flagship new visitor development.

 It has since become a landmark scheme in the Northwest.

Products applied

The roofs were completed using the Bauderflex system enhanced with a green roof, with all materials supplied directly by Bauder. The build-up included the KSD Mika vapour control layer, 140 mm BauderPIR insulation boards and the self-adhesive BauderTEC Sprint DUO underlay. Waterproofing was provided by the BauderPLANT E 42 root-resistant cap sheet, with BauderFLEX K4E charcoal grey cap sheet installed to all edges and perimeters.

Due to roof pitches exceeding 10 degrees, a restraint detail was incorporated using a 300 mm strip of 18 mm plywood, mechanically fixed with tube fixings to prevent any future movement of the green roof system. Insulation thicknesses were carefully coordinated with this detail, so the restraint remains hidden within the finished roof build-up. The roofs were finished with a pre-grown Bauder sedum blanket, providing an instant living roof while supporting the client’s environmental and visual requirements.

All materials were installed in line with Bauder’s technical guidance, with ongoing coordination between Safeseal Roofing, Starship Group and Bauder’s technical team to ensure the build-up performed as intended.

Project challenges

One unexpected challenge on the project was the lifting and placement of the pre-grown sedum blanket across a large, spread-out site. Due to the distances involved and the angles required to reach certain lodge roofs, the original lifting arrangement did not provide sufficient control to position the sedum safely. To address this, close collaboration with the crane company was required to source an adapted lifting attachment that allowed the sedum to be placed accurately and without damage. Although the component had to be delivered from the south of England, (resulting in a short delay), the solution ensured safe handling of the living roof materials and avoided any compromise to quality.

Weather conditions required careful management. Periods of hot, dry weather created additional considerations for installing living roof materials. To protect the sedum blanket, deliveries were carefully timed to avoid peak heat, and it was regularly watered to prevent it from drying out prior to installation. Where necessary, the order of works was adjusted to focus on preparation and detailing, allowing sedum installation to proceed immediately once conditions were suitable.

By keeping an open communication with Starship Group, Safeseal and the wider site team, these challenges were successfully overcome without impacting the programme or the quality of the finished green roofs.

The result

The Zoo required a natural green roof finish that blended into the surrounding landscape while delivering reliable waterproofing, consistent thermal performance and a healthy growing base for the sedum blanket. The Bauderflex system is a detailed specification that relies on accurate build-up and precise setting out at every stage. To ensure buildability, Safeseal Roofing worked closely with Bauder’s technical manager at the early design stage, reviewing drawings and confirming that the vapour control layer, insulation and two-layer waterproofing system were fully compatible with the timber frame construction of each lodge.

Also, given the layered nature of the green roof system, getting the detailing right at every stage was critical. Any inaccuracies during early installation would have affected the final sedum finish and long-term performance. This required efficient and precise coordination between Safeseal Roofing, Starship Group, the design team and Bauder’s technical team. Through this collaborative and considered approach, a consistent green roof finish was delivered across the development, meeting the client’s visual, environmental and performance objectives.

The contract value was £1.1 million and covered approximately 5,000 square metres of roofing. The completed green roofs aim to support Chester Zoo’s environmental objectives for many years to come.