5-6 St James’s Square

London SW1
GMW Architects
Sir Robert McAlpine
Quantity Surveyor
EC Harris
Corporate and Commercial

Project Scope

  • Curtain walling + stainless steel treatment
  • Curved glazing
  • Glass ramps and main entrance
  • Portland stone cladding
  • Architectural metalwork + rainwater goods
  • Windows and doors
  • Brise soleil
  • Plant enclosures
  • Louvres and exhaust risers
  • Aluminium cladding + column covers and soffits

Located in the West End’s most exclusive address, mining giant Rio Tinto redeveloped their existing HQ into a high end commercial office space and residential block.

Key Challenges

  • 50mm thick Portland stone façade hung off curtain walling system
  • Curved stainless steel façade hung
  • Numerous different interfaces with multiple finishes
  • Logistically challenging site constraints within a highly sensitive neighbourhood

The Brief

The highly sensitive conservation location and demand for premium quality meant a challenging proposition for Colorminium. Engaged by Sir Robert McAlpine when the design was already at Stage E, our scope of works was embracive and covered all the façade elements with the exception of the brickwork. This broad project remit meant our role in the delivery was pivotal with our services including leading the control of all major interfaces through the design phase through to liaison with Building Control and Westminster Planning Officers.

Our Approach

The project carried a number of complexities that needed careful consideration. As an 8 storey building with a steel frame, the speed of construction was quick and dictated that the installation on the facades was fundamental to achieve watertight dates and release the internal fit-out. Due to excessive deflections and a high volume of interfaces, stickwork curtain walling was utilised in the glazing zones with the finishes and cladding materials occurring once this was off the critical path.

Of particular note is the courtyard area where a handset Portland stone façade was re-engineered as a rainscreen with all loadings taken back to the curtain walling to avoid multiple penetrations of the performance line. Another area of complexity was a stainless steel façade hung from the floor slabs and with large high specification curved glass units.

With the building watertight and sensitive finishing materials progressing, our focus switched to the detailing and completion of other complex areas such as 4-ply glass ramps, revolving and swing doors with architectural lattice work and architectural bronze cladding.

The Result

The accolades from the client team were fitting to what proved to be a challenging engineered solution. Completed on time and within a tight budget, the finish is stunning and sympathetic with its location and will stand as a hallmark for the profession in which it was delivered.