Belfast Grand Central Station
Belfast, Northern Ireland
Date Completed
2025
Sector
Infrastructure
Main Contractor
Farrans / Sacyr Joint Venture
Project Overview
Project Context
Belfast Grand Central Station is a major transport hub located in Belfast city centre on the former Europa Bus Station site. It brings together rail and bus services within a single facility and sits within a constrained and security-sensitive part of the city.
Thornton was appointed by Farrans/Sacyr Joint Venture to deliver the roof package. The works covered approximately 13,000 m² of roofing, forming a key architectural feature made up of ten individual pitched roof zones with varying geometry and high visibility from surrounding buildings.
Scope of Works
The package included the design, supply, and installation of a Kalzip aluminium standing seam roof across the full development, along with bespoke external soffits and train platform canopies.
The roof build-up comprised Kalzip 65/400 aluminium standing seam sheets in a 0.9 mm stucco mill finish, installed over a Kalzip liner deck, continuous vapour control layer, and a dual-layer glass fibre insulation system. This was supported on a steel top-hat substructure and fixed using a combination of sliding and fixed clips to allow for thermal movement.
Concealed PVC-laminated gutters were integrated within the roof build-up, along with aluminium flashings at ridges and eaves. The works also included permanent access provisions in the form of walkways and free-standing aluminium handrails.
All junctions, including ridges, valleys, and interfaces with curtain walling and structural steelwork, were formed to maintain continuity of the weathering layer, insulation, and airtightness.
Suppliers
Technical Delivery
Key Challenges & Solutions
The security context imposed blast-resistance criteria, pushing the design well beyond typical standing-seam construction. The system was analysed using finite element modelling to understand its behaviour under load. To meet this, fixing densities were significantly increased, clip arrangements were reinforced, and the top-hat substructure was re-engineered, resulting in over 500,000 fixings across the roofscape.
The roof itself added another layer of difficulty. Ten separate zones, each with different pitches and integrated concealed gutters, meant there was no repetition. Maintaining continuity of the vapour control layer, insulation, and weathering across all of these transitions required careful detailing. Bespoke solutions were developed for ridges, gutters, and eaves, with extensive coordination required to ensure everything aligned with the wider façade and structure.
Panel lengths of up to 38 m exceeded conventional handling limits. A Kalzip mobile roll-former was craned onto the roof to produce sheets in situ, supported by bespoke lifting beams and temporary works design. Lower zones utilised ground-rolled 22 m sheets, while upper zones were formed at height to eliminate transport damage and maintain geometry.
The city-centre site constrained logistics. A viaduct beneath the works restricted crane positions and required engineered spreader pads. Limited laydown space and live public interfaces demanded just-in-time deliveries and controlled unloading. Installation tolerances were tightly managed using laser set-out, enhanced ITP hold points, and a deliberately small specialist crew to maintain consistency.
Performance Outcomes
The completed roof meets all structural, blast, and fire performance requirements set out for the project, including full A1 non-combustibility.
It provides a continuous and robust weathering solution across a complex roof geometry, while maintaining airtightness and thermal performance throughout. The visual finish is consistent across all roof zones, despite the variation in form.
The works were delivered in line with the overall programme, despite the level of technical and logistical challenge involved. Integrated walkways and fall protection systems now provide safe access for ongoing inspection and maintenance, supporting the long-term operation of the building.
The project demonstrates how a standing seam system can be engineered to meet exceptional blast, fire, and architectural demands while maintaining constructability and programme certainty for a nationally significant infrastructure project.
Duane McCredie
Project Director at Farrans/Sacyr JV
“Their team exhibited exceptional professionalism, ensuring that all works were carried out to the highest industry standards, on programme, and in full compliance with safety and quality requirements.”
“Thornton Roofing delivered an exemplary service on the Grand Central Station Kalzip roofing project. The scope and complexity of the installation demanded a high level of technical expertise, meticulous planning, and disciplined execution. Thornton Roofing consistently demonstrated these qualities throughout the project.
“Their team exhibited exceptional professionalism, ensuring that all works were carried out to the highest industry standards, on programme, and in full compliance with safety and quality requirements. The collaborative approach adopted by Thornton Roofing contributed significantly to the successful delivery of this high-profile project.
“As Project Director, I can confirm that Thornton Roofing has proven itself a trusted and highly capable contractor. I would have no hesitation in recommending them for future major infrastructure and roofing projects.”
How the project came to life
