Project: Glasgow University
Location: 50-58 Hillhead Street & 73-81 Great George Street, Glasgow
Main Contractor: Morris & Spottiswood
Supplier: SIG Roofing – James O’Hara
Products: SIGA 120 random diminishing slate from the 120 Excellence range, Tyvek Supro Felt, BLM lead, Hargreaves Cast Iron Rainwater Goods
Type of property: Educational/Commercial 2,500 M2
Date completed: October 2023
Background:
Since 2020, a dedicated team within the University of Glasgow has carefully assessed the condition of their existing assets, highlighting the critical need to invest in their historic buildings.
Part of this project involved preserving the properties on Hillhead Street and George Street to protect the University’s architectural heritage for future generations. The project included making external repairs to the buildings on Hillhead Street and Great George Street to ensure they were weatherproof. The focus was on enhancing the buildings’ sustainability and thermal performance.
The work included the large roofing area of the building block, and specific guidelines were provided for selecting products to preserve the site’s cultural heritage. The project required products that would enhance the existing 19th-century style while meeting modern sustainability and thermal performance standards. Each product was carefully chosen based on its aesthetic appeal and leading technical specifications in the market. Budget was also a consideration, as Glasgow University is a not-for-profit organisation that prioritises optimising limited budgets.
Roofing product choice:
Great George Street is located within the Glasgow West End Conservation Area. Selected products needed to blend seamlessly into the local heritage and respect the craftsmanship evident in the area. With a project roofing area of 2500m2, traditional Scotch slate was not an option, while the SIGA120 had just the right blend of quality, style and appearance to fit perfectly into the conservation area.
DM Roofing (DMR) of Kilmarnock specialise in listed and historically important building roof restorations. The team in AccuRoof, the specification division of SIG Roofing, supported the contractors when identifying which slate would fit the project best. Welsh slate was originally identified as a solution for the roof; however, when the Accuroof team looked at the size of the roof compared with the phased requirements to fit, they found that the slate would be quarried at too low a rate for the schedule. That’s when they offered SIGA120s as a quality slate with the right logistical support for the project needs.
SIGA 120 is a unique indigenous alternative to traditional Scottish slate. Sourced in Wales it is a true alternative to, amongst others, the extinct Ballachulish slate. As part of the Excellence range of slate from SIG Roofing, all SIGA120 slates comply with EN12326-1:2014 and have a representative performance of Thermal Cycling T1, Exposure SO2 S1 & Water Absorption W1 (≤0,6%); it also comes with a 75-year warranty.
Installation:
The work included replacing the existing roof coverings with a traditional slate finish, overhauling the traditional timber-framed windows, and addressing the defective rainwater goods. The project also included removing and renewing all sarking boards in conjunction with slate replacements. At the same time, other contractors were involved in carrying out render repairs and leadworks to the valleys, gutters, hips, Velux, and skylights.
Although the slating of the roof did not present too many difficulties, it was the scale of the area that provided the biggest challenge. The roof area was vast and although there were various large areas of pitched roofing there was just as much time spent on the smaller more intricate turrets and vertical panels.
Prior to delivery, the slates were sorted, graded, and holed where necessary as per BS 5534 and BS 8000. They were sorted into different thicknesses, and odd slates were set aside for use on eaves or as top slates. The slate is holed from the back, creating a countersunk area that allows the nail head to sit neatly and increases waterproofing and longevity.
The project benefitted from the expertise of DMR’s experienced team on this project.
Logistical challenges:
The University is a hive of activity, with the streets surrounding the property full of the hustle and bustle of student and city life. The building also remained occupied during the renovation work, which created access challenges.
Therefore, specific delivery times were allocated to the project team to avoid congestion, which required tight management of the bill of materials. DMR worked closely with the SIG Roofing branch in Linwood to ensure that logistics fitted the narrow delivery windows and loads were dropped off on time and in full.
On site materials management came to the fore with this project too. Each phase had a strict timeline and with street restrictions limiting the space dedicated to storage, the contractors had to work closely with the SIG Roofing branch to deliver the slate in a steady flow, including certain sizes to account for the length of the roof.
As the one reliable facet of Scottish weather is rain, it was critical to ensure the roof remained watertight at all times. A particular concern were the turrets, as cutting the sarking board was a painstakingly detailed process, each board needed to be trimmed into a precise tapered shape which took time and skilled patience. This could have delayed the project significantly, but the phased planning allowed the team to work diligently through each section without undue disruption to other contractors and the building’s inhabitants.
Teamwork between contractors, colleagues and suppliers was the essential ingredient in delivering this project successfully. There were a number of different contractors covering stonework, windows and internal fitouts. This presented a logistical imperative to coordinate all moving parts into a well-structured, phased, approach.
The project was delivered on time and within the budget allocated for the roof work.
