Background:
The St. Gabriel’s project involved a careful restoration of the historic St. Gabriel’s Lodge, Chapel, and Woodthorpe Hall. It also included the construction of two complementary buildings, providing a total of 319 high-quality student bedrooms near Manchester University. McClaren Construction was awarded the project, working with Simpson Haugh & Partners as the architects and ALB Roofing Developments as the specialist roofing contractor.
The slate roofs to the lodge had reached the end of their life expectancy with cracked and damaged slates throughout. The fixings were starting to fail and the lime parging to the underside of the slates had mostly dropped off, compromising the weatherproofing and leading to water ingress in several locations. As a building adjacent to a conservation area, the project required a sensitive refurbishment of the key heritage assests.
Accuroof part of SIG Roofing, collaborated with ALB Roofing to supply roofing materials for the project. Specifically, the pitched roof needed a complete replacement while maintaining the historical aesthetics of the original structure.
Roofing product choice:
The original building featured Welsh slate, which needed to be replaced. Sourcing Welsh slate in large quantities can be challenging and expensive, so after discussions with AccuRoof, ALB Roofing opted for SIGA 32 slates. These textured blue-grey slates are suitable for a variety of roofing projects. Although they are supplied from Northwest Spain, they have received Snowdonia National Park approval as a quality replacement for Welsh slate.
The project involved the installation of 19,000 of these Spanish slates across various sections of the refurbished student accommodation. The slates used were 5mm thick and measured 500mm x 250mm, although the range is also available in 7mm, 8mm, and 9mm thicknesses, as well as various slate sizes. The SIGA slates conform to BS EN 12326-1:2014 – T1/S1/W1 and come with a 75-year warranty. For more details on SIGA slate products, please visit https://www.sigaslate.co.uk/.
The SIG Roofing Manchester branch supplied the natural slates, associated fixings, and clay ridge tiles, all of which were essential to delivering a roof finish that met both the aesthetic and performance expectations of the build.
Aaron Bryant, Managing Director of ALB Roofing explained the product selection:
“The decision to use SIGA 32 slate was the result of a careful review of both product performance and availability. Given the scale of the project and the aesthetic requirements to match the character of the original roof, we needed a product that could meet both visual expectations and supply demands.
We’ve built a strong working relationship with the team at AccuRoof over the years, and in particular with their regional slate specification manager, Chris Biddick, whose technical guidance and product knowledge have consistently supported our delivery of heritage-sensitive roofing schemes. For this project, we reviewed multiple samples and evaluated them in situ to ensure the best possible match in texture, tone, and quality.
The SIGA 32 stood out as the ideal choice not only for its appearance and finish, which aligned beautifully with the existing architecture, but also for its availability in the volumes we required. AccuRoof’s involvement helped streamline the specification and procurement process, ensuring confidence and consistency from selection through to installation
Installation:
On site, the first task for the ALB Roofing team was to carry out a full roof mapping of the existing structure. They recorded each course and carefully noted the frequency and position of the original scalloped details. This formed the basis of the new layout, enabling them to replicate the original pattern, proportions, and visual appearance with accuracy.
Following this, all existing roof coverings were removed, including the slates, battens, felt, and associated components. The exposed roof structure was fully inspected, and any defective timbers were replaced or reinforced in line with current standards.
Before any slate installation could begin, the contractors completed all associated leadwork. Heritage lead-lined gutters were installed, including concealed verge details and T-PREN expansion joints to accommodate thermal movement. This stage was critical to ensure a watertight finish beneath the lowest course of slates and allowed internal works to progress without delay.
A breathable underlay was then installed in line with BS 5534 requirements, followed by factory-graded timber battens. Each batten course was marked out and checked against the previously recorded measurements to ensure consistency across the entire elevation. Vertical datum lines were struck to guide the slating teams and ensure all perp joints remained straight throughout the build.
Slates were fixed in accordance with the mapped layout, with the hand-cut scalloped courses introduced at the original intervals to match the previous detailing. Each slate was hand-laid and fixed using copper clout nails, offering both longevity and a high-quality aesthetic suitable for a heritage-sensitive project.
To complete the roof, new clay angled ridges were installed, mechanically fixed. Final checks and inspections were carried out to ensure the finish was uniform, secure, and in line with the original specification.
Logistical challenges:
This project is located within the Victoria Park Conservation Area in Manchester, which meant the work had to meet strict heritage and conservation standards. From the outset, the focus was on ensuring that the new roofing complemented the architectural character of the original building.
The project also presented a number of logistical and coordination challenges. With a large volume of trades operating on-site simultaneously, close collaboration and precise scheduling were essential to ensure the roofing works progressed smoothly and efficiently.
Material handling was another significant factor. With very limited on-site storage, they had to plan and manage the phased delivery and installation of over 19,000 natural slates, not to mention a further 66,000 Rosemary tiles used on the adjacent Woodthorpe building. Efficient stock control and delivery became critical to keeping the works on track without overloading the site.
A strong working relationship with McLaren’s commercial team was key to overcoming these challenges. Their support and coordination played a central role in helping deliver high-quality results in a highly complex working environment.
