The Centre for Agriculture and Biosciences International (CABI) is an inter-governmental, not-for-profit organisation that improves people’s lives worldwide by providing information and applying scientific expertise to solve problems in agriculture and the environment.

The old CABI headquarters, a former school building, had become outdated and was no longer fit for purpose, being uneconomical in terms of layout and energy efficiency, and required a high level of maintenance.

The specification

The client’s objective for the new headquarters was to construct an eco-building that made a statement, whilst also blending into the surrounding countryside.

For the roof, Bauder’s lightweight Thermofol PVC waterproofing was specified with an extensive sedum blanket to create a green roof. Rooflights were incorporated to provide natural top light, helping to reduce demand for electric lighting and help lower CO2 emissions.

The technical and sustainability expertise and support available from the Bauder technical team and area manager, coupled with the comprehensive guarantee package made Bauder the ideal supplier to work with the architects on this project.

Products applied

Bauder THERMOFOL U15 V FR PVC:

This single ply membrane is lightweight and has a high-grade virgin polymer formulation. The PVC formulation ensures it is resistant to chemicals and micro-organism attack making it well suited to receive a green roof.

BauderPIR FA Insulation:

To achieve efficient drainage and taking into consideration the shape of the roof, BauderPIR FA Insulation was specified on the CABI project. This insulation is lightweight, cost effective and easy to install. The low thermal conductivity allows for the insulation to be of reduced thickness compared to other insulants and the layout scheme is designed to produce minimal waste.

BauderGREEN XF 301 Sedum Blanket:

Bauder’s XF 301 Sedum Blanket is a mature vegetation blanket, sown with a variety of sedums. It is intended for application directly over the waterproofing system without the need for a secondary substrate growing medium, making it the lightest self-contained sedum blanket system available.

Project challenges

The curve of the roof, which at some points reached a pitch of over 30 degrees, posed a number of challenges. Firstly, we had to ensure that the roofing contractors could safely install the Bauder system to the required standard, even with the extreme pitch. To meet this challenge, retaining battens were used where the pitch was at its steepest. When fixing the battens to the metal deck, there had to be a sufficient bond to the deck to ensure adequate attachment. With the deck exposed below, mechanical fixings had to be used sparingly so that they were not seen. The curve of the roof also had to be factored into the fixing of the sedum blanket. Retention strips were added to the design to hold the sedum in place securely and prevent any slippage. These were spaced at a 1m distance to ensure a strong and secure install.  The ongoing maintenance of the roof will be facilitated by the access walkways and safety systems that will remain in-situ, providing safe access for watering, fertilisation, and general maintenance.

The result

CABI’s new office building demonstrates striking architecture by Scott Brownrigg Architects. In keeping with CABI’s role as an environmentally concerned organisation, the building will perform to a very high level of sustainability. The office provides a modern, comfortable, and efficient working environment and a number of facilities available for use by the local community.

BauderGREEN Sedum System with Bauder Thermofol PVC