18-20 Grosvenor Street

London W1
Grosvenor Estates
Flanagan Lawrence
Sir Robert McAlpine
Quantity Surveyor
EC Harris
Corporate and Commercial

Project Scope

  • Bronze windows and doors
  • Main entrance portal
  • Aluminium windows
  • Feature bays/projecting windows
  • Curtain walling
  • Brise soleil
  • Cladding
  • Rooflights
  • Architectural metalwork

20 Grosvenor Street is a new Grade A commercial office space, successfully brought together from two neighbouring buildings.

Key Challenges

  • High level of quality with premium finishes
  • Bespoke window and glazing solution to meet planning requirements
  • Very complex delivery methodology within Mayfair
  • High level of interfacing with other trades for seamless envelope performance

The Brief

Colorminium were engaged by main contractor Sir Robert McAlpine whilst the design was still at Stage D. Working alongside them and the architects, the detailed design was worked up through Stage E before the design responsibility rolled over at commencement of Stage F. Featuring a retained façade to 18 Grosvenor Street, the remainder is new build with the front elevations stone clad and the rear elevations and light well brick clad – both with inset glazing.

Our Approach

A very high quality project with a prescriptive architectural intent that had been driven by Westminster planning authority had a big challenge in that it could not be achieved with proprietary systems. After being engaged, Colorminium worked closely with a number of suppliers to source and adapt a framing and glass design that was feasible but carried a number of risks requiring mitigation.

A further key feature of the design was the maintenance of the weathering and performance lines on the envelope. The contractor and architect had opted to clad the frame in pre-cast panels mainly due to the complex logistical challenges and party wall abutments, which meant close co-ordination was required to ensure the interfaces were carefully detailed.

With insert windows to the stone and brick facades the building had lightwells down each party wall flank which had rooflights installed at ground level giving natural light to the basement. At rooftop, the top floor was clad in curtain walling with brise soleil to the south facing elevations. The main entrance onto Grosvenor Street had a complex pure bronze portico design that incorporated several key features such as rainwater goods and access control.

The Result

A stunning finish to this office building is testament to the lengthy and challenging design phase. A focus on engineering the small, bespoke details paid off with a truly magnificent end product that marries a new build perfectly into the conservation environment it sits in.