Sainsbury Laboratory, University of Cambridge Botanic Garden

Project: Sainsbury Laboratory, University of Cambridge Botanic Garden

Hydrotech MM6125 Structural Waterproofing from Alumasc, has been used on the new Sainsbury Laboratory, overcoming numerous challenges presented by the roof’s unusual design.

The award-winning scheme, designed by architects Stanton Williams is an 11,000m2 plant science research centre set in the University of Cambridge Botanic Garden. The concrete roof deck features a range of complex details such as photovoltaic panels, roof lights, exposed roof edge details and sunken wells housing mechanical and electrical services.

Alumasc’s Approved Contractor Fenland Flat Roofing installed 6000m2 of Hydrotech MM6125 structural waterproofing over the concrete roof deck during a six-month period which took them through the winter of 2010/11. The Hydrotech system was chosen for its high performance bituminous rubber blend which allows fast and simple installation over complex roof details and around penetrations.

Andy Bacon, Director of Fenland Flat Roofing, comments: “On most projects, the waterproofing is covered by cladding or other details where it interfaces with the edge of the roof, but this was a fair-faced concrete finish with the waterproofing exposed where it met concrete columns on the edge of the building. Our installation team had to be extremely precise in perfecting this detail, leaving a very crisp, clean edge to the roof.”

The building’s environmental features also tested the skill of the installers. Pebbles were used as ballast around the photovoltaic cells, whilst paving slabs have been used as walkways to provide access to the sunken wells which are designed to hide the M&E services below the roofline.

“Getting the waterproofing details correct around the sunken wells was particularly difficult,” says Andy Bacon. “However, Hydrotech is flexible enough to tackle tricky details such as this. We also put safety systems in place to ensure the bituminous membrane was safely installed to a high standard.

“Despite the challenges, the project has gone very well thanks to a great team effort from Fenland, Alumasc and the main contractor, Kier Regional.”

The project has won several major awards including 2011 World Learning Building of the Year WAF Award; the 2011 Concrete Society Award and was highly commended in the Major Project category of the British Construction Industry Awards. It has also been awarded a BREEAM “excellent” rating for its outstanding environmental performance. 

Manufactured using 10% post-consumer recycled material, Hydrotech’s unique formulation guarantees lifetime performance.  Hydrotech is fully warranted, BBA Accredited and has European Technical Approval ETA-05/0152.


For more information on Alumasc’s high performance structural waterproofing systems, please visit or for literature, please call 0808 100 2008.