The firm will start work later this month on the redevelopment of Evershed House at 70 Great Bridgewater Street.
Designed by OMI Architects, the building will be stripped back to the frame and extended upwards by two floors to offer 110,000 sq ft of office space targeting BREEAM Outstanding.
The existing masonry facade on the 2001-constructed building will be replaced with a unitised curtain wall and aluminium cladding façade system.
Gilbert-Ash Construction Director, Raymond Gilroy said: “We are delighted to be working for Bridgewater Manchester (Luxembourg) Holding Sarl on this project, not only to complete refurbishment but also to extend this office block in the heart of the city.
“The completed works will provide CAT A office space over eight floors making 70 Great Bridgewater Street one of the most innovative and modern places to work in Manchester.”