The main construction package for a major redevelopment of the former Courage Brewery headquarters on the River Thames in Staines, Middlesex will come to market this summer.
Capita Symonds owned ESA unveiled plans for the scheme this week after planning consent was granted by the local authority.
Work is expected to start this autumn.
The plans include the refurbishment of the 60,000 sq ft office and underground car park, stripping back the entire building to its robust concrete frame and waffle slabs while reconfiguring parts of the plan to given an additional 20,000 sq ft of floor space.
The original building, named Ashby House after local brewer Thomas Ashby, was constructed in 1989.
It has a distinctive three storey pitched roofed structure and banded brick cladding which will be removed.
ESA design director Nic Sampson said: “The result is effectively a new-build, providing Grade-A office space in the heart of the town.”