St Michael's Hospital

Bauder Total Roof System (BTRS) with BauderSOLAR


The original waterproofing on the Maternity Hospital roof had exceeded its serviceable life and begun experiencing water ingress, requiring urgent remedial work. Bristol City Council wanted to optimise the roof area by installing a high quality, long lasting PV array that would contribute to its Solar City scheme that aims to provide one gigawatt of solar power to Bristol by 2020. The installation needed to cause minimal disruption to ongoing work at the hospital and insulation upgrades were necessary to ensure the roof achieved the required 0.25 U-Value.

Bauder Building Board

Project: St. Michael’s Hospital
Location: Bristol
Project type: Refurbishment
Roof size: 1,170m²
PV roof area: 500m²
Client: Bristol City Council
Specificier: British Royal Infirmary
Approved contractor: Span Roofing Contractors Ltd

The specifcation

Bauder’s premium bituminous system, BTRS, was specified because it is durable, robust and can withstand permanently sited loads of up to 2000Kg/m². The system build-up included Bauder’s 100mm PIR FA-TE insulation to satisfy building regulations, and its state-of-the-art PV modules were installed at a 10⁰ angle for optimum energy generation. The solar array consisted of 166 PV modules in total, enabling the hospital to generate at least 41.98 Megawatt Hours of solar power each year. The remarkable simplicity of the installation method also meant that the entire array could be fitted in just three days.

System installed

Bauder Total Roof System (BTRS)


1 Bauder K5K A heavy duty, torch-applied SBS modified elastomeric bitumen capping sheet.
2 BauderTEC KSA DUO A technically advanced self-adhesive SBS elastomeric bitumen underlayer with “DUO” lap technology to ensure thorough sealing of lap joints, even in lower temperatures.
3 BauderPIR T G An un‐faced tapered insulation which is light weight, has high compressive strength and is made from rigid polyurethane foam.
4 BauderTEC KSD FBS A technically advanced, robust, self-adhesive SBS elastomeric bitumen air and vapour control layer.


Richard Lowe, Project Specifier, at Bristol City Council:
“Bauder offered the highest degree of service and support throughout the project. We were delighted to find a single source solution of roof renewal with PV supply and fit, and with the complete roof finish covered by the Bauder guarantee we have total peace of mind over its future performance.”