Associated Steel Window Services (ASWS) has completed a complex restoration project involving historic steel windows at the landmark County Hall building in London, part of the London Marriott Hotel County Hall overlooking Westminster Bridge.

The contract focused on the fifth and sixth floors of the historic structure, once home to the Greater London Council (GLC). ASWS was selected partly due to its extensive experience working on the building, having completed multiple restoration projects there over the past three decades. The latest project marked the company’s first collaboration with Red Construction, the main contractor, and Studio Loren, which led the architectural design.

The works involved restoring 40 steel windows, including 15 crescent-shaped porthole windows featuring large circular roundels with no opening vents, alongside approximately 25 rectangular windows measuring around 1800 × 2000 mm. Many frames required extensive repairs to their through-glazing bars, while sections of glazing had to be replaced and all ironmongery components removed and refurbished.

One of the project’s main challenges was the absence of external scaffolding, which required specialist safety procedures during deglazing operations. ASWS implemented strict safety protocols, including a tool-tethering system (NLG – Never Let Go) to secure tools to operatives working at height and prevent falling objects.

Most windows were restored in situ, though two heavily corroded units, previously concealed behind a false wall, had to be removed and fully refurbished off-site. As the original Mid-Universal steel sections are no longer manufactured, replacement components were fabricated manually from flat bar and angle sections at the ASWS workshop before being welded into the frames.