Marischal College, Aberdeen | Restoration Case Study

Our role: Specialist masonry contractor to Sir Robert McAlpine
Client: Aberdeen City Council (main contractor: Sir Robert McAlpine)
Awards: GIA Design Awards 2011: Commendation, Conservation, with Laing Traditional Masonry credited for the traditional building craftsmanship. Aberdeen Civic Society Awards 2011: Award for the redevelopment and Award for Craftsmanship for the masonry on Marischal College

Marischal College is a Category A listed Tudor-Gothic complex completed in 1906 and one of the largest granite buildings in the world. Working for Sir Robert McAlpine on the façade retention scheme that created Aberdeen City Council’s new headquarters, we cleaned, repointed and restored the granite façades. The redevelopment was commended for Conservation at the GIA Design Awards 2011, with Laing Traditional Masonry credited for the traditional building craftsmanship, and the Aberdeen Civic Society Awards 2011 gave it an Award and a separate Award for Craftsmanship for the masonry.

The challenge

The sheer scale of the work was the defining challenge. Around 12,000 linear metres of hard cement pointing, between 2 and 8mm wide, had to be cut out of high-quality Kemnay granite with sharp arrises, without damage, and then repointed. The project also involved substantial new granite-faced walling in lime mortar and complex structural alterations to form new openings behind the retained façades.

Our solution

The pointing mortar, based on NHL 3.5 lime and local sand with a natural air-entraining additive, was designed for the exposed conditions. LTM Materials pre-mixed all pointing mortars off site from kiln-dried sands, giving consistent quality across the whole project and improving productivity on site. Defective blocks were replaced with Kemnay granite quarried specifically for the project, and our masons carved new granite details to match.

“The overall appearance of the cleaning and repair works is outstanding. This is due to the continuous attention to quality and detail that has been present throughout the works. A high level of consistency, critical to the final appearance of the project, has been achieved. The final appearance of the cleaned and repaired sandstone tracery to the Quadrangle is particularly pleasing for its sensitivity to the historic value of this stonework.”

Nicola AshurstStone cleaning and conservation consultant, March 2011

Outcomes

Façades brought back to life

Careful cleaning removed decades of pollution to restore the granite’s original sparkle.

Consistent quality at scale

Off-site pre-mixed lime mortars ensured identical performance across 12,000 linear metres of pointing.

Delivered on programme

The masonry works were completed on time and within budget, with the topping-out ceremony held in February 2011.

Craftsmanship recognised

Commended for Conservation at the GIA Design Awards 2011, with Laing Traditional Masonry credited for the traditional building craftsmanship, and an Aberdeen Civic Society Award for Craftsmanship 2011 for the masonry on Marischal College.

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