Perth High School
Perth High School is a major Passivhaus development incorporating a Bauder Thermofol system across a complex roof layout to deliver the airtightness and thermal efficiency essential to meeting strict energy targets.
Synopsis
Perth High School is one of the first and largest Passivhaus schools in Scotland, representing an £80m investment in the city’s education infrastructure. Built on the existing site to replace a 50-year-old building previously rated poor for suitability, the new development accommodates up to 1,600 pupils and 140 staff across a modern, three-storey facility.
Designed to Passivhaus standards, the scheme places strict demands on energy performance, requiring exceptional levels of airtightness and thermal efficiency. The roof construction was central to achieving these targets, particularly given the scale of the building and the need to maintain continuity across multiple areas and interfaces.
Bauder building board
Project | Perth High School |
Location | Perth, Scotland |
Project type | New Build |
Roof size | 5696 m2 |
Main contractor | Robertson Construction Tayside |
Approved contractor | Briggs Amasco Ltd |
The specification
A Bauder Thermofol PVC single ply warm roof system was specified to meet the project’s demanding performance criteria. Central to the build-up was the incorporation of 320mm of BauderRock mineral wool insulation, installed in two layers to minimise heat loss and support the building’s overall thermal efficiency strategy.
The insulation was carried across all roof areas, including upstands and changes in level, ensuring a continuous thermal envelope in line with Passivhaus requirements. Strict tolerances were maintained throughout, with no gaps greater than 3mm permitted between or beneath insulation boards.
The Bauder Thermofol membrane provided a durable and reliable waterproofing layer, while its adaptability allowed consistent detailing to be achieved across complex geometries. The system’s proven compatibility with both concrete and steel deck substrates further supported its suitability for this large-scale, multi-zone installation.
Products applied
Bauder’s Thermofol 1.5 mm Single Ply roofing system was chosen for this project specifically for its environmentally balanced properties. MLA also preferred single ply membranes of a specific grey colour shade and once compared to the option of using bitumen especially in terms of carbon emissions, the bitumen option would not make it suitable for the project as it is intended to be an environmentally friendly building.
Single ply membranes are durable and resistant to European climate considerations, yet incredibly lightweight, typically 2-3kg/m2 making the transportation of materials as easy and efficient as possible. Due to its durability, using single ply means the roof would last longer and therefore it is less likely for the roof to require continuous refurbishment and refresh.
Bauder PIR Tapered insulation was chosen for its lightweight and exceptional lambda value ensuring the roofing system was as energy efficient, thin and light as possible.
Project challenges
Delivering the roof in line with Passivhaus standards required precise installation and close control of detailing throughout. Changes in level across the atrium, sports halls and plant areas introduced complexity, requiring a consistent approach to maintaining continuous insulation and preventing cold bridging.
A staggered, two-layer insulation build-up was developed at junctions to ensure thermal continuity, while strict tolerances of no more than 3mm gaps were maintained across all areas.
Handling and installing 320mm mineral wool insulation also required careful quality control, with all boards inspected throughout delivery and installation. Specialist cutting equipment was introduced to achieve the necessary accuracy.
Health and safety was managed through a structured, site-wide approach, including daily briefings, permit systems and regular inspections. Design-stage measures such as permanent edge protection, designated access routes and reinforced walkways further supported safe working, alongside the use of an air-filled fall arrest system within the atrium area.
The result
The completed roof provides a robust, airtight and thermally efficient solution aligned with Passivhaus principles, contributing to a building that exceeds its targeted energy performance. Thermographic surveys and airtightness testing confirmed the effectiveness of the installation, demonstrating the integrity of the thermal envelope.
Delivered across approximately 6,000m², the project highlights the capability of Bauder single ply systems to support technically demanding, large-scale education buildings where performance and precision are critical.
The quality of both the installation and on-site practices has been recognised through the project’s shortlisting as a finalist in the SPRA Awards 2026 for both the Best Refurbishment and Health and Safety categories. This reflects not only the standard of workmanship and detailing achieved, but also the proactive and comprehensive approach taken to managing health and safety throughout the works.
The Perth High School project stands as a strong example of how rigorous design coordination, specialist installation and a well-engineered roofing system can successfully deliver high-performance outcomes on complex, future-focused developments.