JM Architects

The Crown Estate

Morgan Sindall

Scope & Products:

  • Heritage Steel Thermally Broken Windows
  • Manufacture of Bespoke Aluminium Extrusion to Picture Frame Windows
  • Bronze Patinated Panelling to Canopy


  • Very demanding specifications and tolerances requiring assiduous attention to detail by our design team
  • Development and manufacture of Dies Casts to allow us to extrude bespoke aluminium to match the existing window transoms and picture frame surround.
  • Bespoke extrusion for picture frame of window to match previous windows
  • Sightlines maintained for planning but requirement of increased high thermal performance system
  • Bespoke lattice work design to glass and framing system
  • Logistically challenging site constraints within a highly sensitive neighbourhood
  • BREEAM Excellence requirement.


We are always delighted to work on prestigious buildings, especially heritage ones – which is why we were very excited to be working on British Columbia House in London. This Grade II listed building is steeped in history and as this building reached its 100th birthday it underwent a £8.5 million refurbishment to restore it to its former glory whilst meeting modern day regulations.

As with all Grade II listed buildings it came with strict planning requirements – the external façade had very stringent design constraints to ensure that the Westminster planning requirements were fulfilled. For this reason, the project required a competent design led partner that not only understood the requirements but also had the facilities and previous experience to deliver the quality of product that is required when working on some of London’s largest and most prestigious heritage buildings.

Employed by the main contractor, Morgan Sindall, Propak worked on the early stages of design, to come up with solutions to meet planning requirements and architectural intent by sourcing materials that were in-keeping, met modern day regulations and met the buildings stunning looks.

Propak designed and developed a bespoke variation to the Janisol Arte framing system, to ensure the highest thermal performance, and integrated custom-made aluminium extrusion and t-sections to the exterior of the frame and glass to mimic the outdated Crittall style windows.

The project was a runner up in the BREEAM Award 2015, a high-profile annual event which celebrates excellence in sustainability, representing the most innovative projects and a variety of inspirational buildings from all regions of the UK and several European countries including the Czech Republic, France, Norway, Romania and Sweden.

It was commented on many occasions that this variation of Propak’s Heritage window system is by far and away the most impressive that has been seen on the market for many, many years.

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