Cambridge University, Department of Civil Engineering

This new build project in the centre of Cambridge combines a Sustainable urban Drainage Solution (SuDS) in the form of the new blue roof system from Bauder - BauderBLUE, a biodiverse green roof and solar PV on top of the insulation and waterproofing, essentially combining four roofing systems in one. Bauder believes this to be one of the first of its type in the UK and so it was new for most of the design and construction team. Good communication between the main contractors, roofing contractors and the PV installers was needed to make sure the installation was efficient.

The project, being one of the first of its type in the UK, combines bituminous waterproofing, a blue roof system, a green roof and a solar PV array, involving new technologies and using existing products in an innovative way. The BauderBLUE system utilises innovative products in the form of the void former and the flow restrictor that controls the water egress, which has no moving parts, hugely reducing the need for maintenance or risk of failure. The Bauder BioSOLAR system incorporates a unique mounting system, lifting the panels above the vegetation allowing it to grow freely and therefore qualify a greater area of the roof as biodiverse. The PV substructure and the drainage board are attached, and the green roof substrate and vegetation provide the ballast to hold the system in place, removing the need for any penetration into the waterproofing.

Bauder Building Board

Project: Cambridge University Department of Engineering​
Location: Cambridge
Roof Area: 1610m²
Specifier: RH Partnership 
Approved Contractor: Voland Asphalte Limited


The roof was being designed with a pretensions concrete plank roof structure. Due to the large span of these planks, the dead load weight to the roof would be restricted. This being a blue roof with green landscaping and PV, presented the issue of balancing the need of the roof design and the restriction of the supporting structure. As the roof was to be a blue roof, the deck needed a dead flat finish with no positive or negative falls. However, the pretensioned deck complicated the situation resulting in the deck being screened flat which limited further the weight Bauder could apply to the roof.

The Bauder team worked very closely with Voland and SDC to ensure installation was carried out to the highest of standards.
Communication between contractors and Bauder was strong throughout the project, working collaboratively to successfully complete the job.

Applied Products

Bauder Total Green Roof System

Suitable for a variety of applications on both new build and refurbishment projects and can be used in warm, cold and inverted roof scenarios.


Bauder BioSOLAR is an integrated mounting solution for photovoltaic renewable energy with a green roof where the substrate and vegetation provide the ballasted installation mechanism, which removes the need for penetrating the waterproofing to secure the mounting units to the roof.


The BauderBLUE Roof System is a sustainable drainage method designed to attenuate and manage stormwater on a flat roof over a 24-hour period via a restrictive flow outlet. A BauderBLUE roof is designed specifically for each individual project.