Nant Caerau Primary School

Synopsis

Nant Caerau is a Welsh‑medium primary school in Cardiff serving a busy local community. This project involved refurbishing the existing school roof by overlaying an ageing metal deck with a new Bauder single ply roofing system. The works were delivered within a live school environment and under strict programme constraints, requiring careful coordination and planning to ensure continuity of operations. The completed system provides a durable, thermally efficient solution designed to improve long‑term performance and reliability.

Bauder building board

The specification

The roofing solution comprised the BauderTHERMOFOL PVC Single Ply System, selected for its proven durability, strong fire performance, and suitability for long-term waterproofing applications. To address the irregular profile of the existing metal roof and improve thermal efficiency, a two-layer Bauder insulation build-up was installed. 

A BauderPIR FA Flatboard infill layer was used to fill the voids created by the seams and profiles of the metal deck, creating a level and continuous substrate. This was overlaid with a BauderPIR FA Flatboard insulation layer, enabling the roof build-up to achieve a minimum U value of 0.15 W/m²K. This combined insulation arrangement was critical in supporting the correct installation and long-term performance of the waterproofing system. 

A BauderSYN DB PE 100 air and vapour control layer was loose laid beneath the insulation to manage moisture migration. The waterproofing layer comprised a BauderTHERMOFOL U15 V FR fleece-backed PVC membrane, reinforced with polyester for enhanced tear resistance and durability. 

Due to the roof pitch exceeding five degrees, the system was mechanically fixed. Wind load calculations were incorporated at design stage to ensure compliance, stability, and long-term system integrity.

Project challenges

The project presented several logistical and technical challenges. The site was extremely constrained, with limited compound space restricting access, storage, and the movement of materials and plant. A detailed logistics strategy was implemented, including phased and just in time deliveries, to minimise congestion and maintain efficient progress. 

The school remained operational during the majority of the works, requiring careful coordination to limit disruption. Daily briefings were held between the site manager and school representatives to align activities, deliveries, and key events. Internal works necessitated the installation of a full crash deck over a main circulation route, with alternative access arrangements put in place to maintain safety. 

A key technical challenge was the integration of the Bauder roofing system with new glazed roof elements installed as part of the wider refurbishment. These interfaces formed prominent design features and demanded precise detailing to ensure full waterproofing continuity. Unknown upstand construction was uncovered once existing elements were removed, requiring rapid on site redesign of details to meet both structural and waterproofing requirements. 

Close collaboration with Bauder’s technical team was essential in resolving these issues quickly, ensuring all revised details complied with building regulations and Bauder’s system standards. Daily inspections were carried out by the site team and Bauder’s technical representatives to maintain quality and performance throughout.

The result

Despite the constraints of a confined site, a live school environment, and a tightly programmed schedule, the project was delivered safely, on time, and to specification. The completed Bauder roofing system provides a robust, energy‑efficient solution that significantly enhances the building’s thermal performance and long‑term resilience. 

All works were carried out in accordance with Bauder’s technical requirements, enabling the system to be covered by a 20‑year Bauder Product and Workmanship Guarantee. Through meticulous planning, adaptive site management, and close technical coordination, the project fully met operational, performance, and programme expectations. The quality and complexity of the installation were further recognised by the project being shortlisted as a finalist in the NFRC UK Roofing Awards 2026 in the Single Ply Roofing category.