Steel window refurbishment vs replacement: What Crittall can do 

• 10 November 2025
• News

The iconic steel window, beloved of the early 20th century Modernist era, has established itself firmly in the ranks of ‘design classic’, and as such, rightly gets recognition for its slim frames, elegant design details and enduring strength. 

However, time doesn’t stand still and the ravages of the decades, including corrosion, can affect an older steel window’s performance, particularly if it has original single glazing. A question we’re often asked at Crittall Windows is: “Should steel window refurbishment preserve what is already in place, or is a full replacement window scheme the better option?” 

Assessing existing windows

The quick answer is that there’s no single rule. Every project begins with careful consideration of the condition of the existing window frames and the architectural significance of the property. Crittall surveyors examine the steel sections, opening mechanisms, glass types and any signs of severe corrosion or distortion. Some existing windows need only targeted repairs. Others have reached a poor condition where failure to act creates an adverse effect on the building fabric. 

When refurbishment is viable it is usually the most sympathetic route. Window refurbishment preserves original windows that contribute to the character of the building while improving function. Necessary repairs might include removing corrosion, treating metal frames, renewing glazing putty, installing new glass with better thermal insulation and upgrading weather seals. These actions reduce heat loss and draughts without changing the appearance of the listed building. The result strengthens the character of the building and respects the guidance of Historic England regarding buildings of special interest.  

When replacement is the better way forward

Refurbishment is not always possible. Some single glazing, combined with heavily corroded metal windows and the absence of weatherseals, needs a more robust solution. In these situations, new steel windows are engineered to replicate existing window frames but with far superior thermal efficiency and air tightness. Double glazing incorporated into slender steel window sections is the most noticeable improvement. Modern manufacturing also provides greater durability so the building is protected well into the future. 

There are strong performance reasons to consider replacement. Older metal frames rarely come close to current expectations for thermal efficiency or acoustic comfort. Introducing new panes of glass with insulated units, improved weather seals and technically advanced steel sections makes a clear and lasting difference. Tenants and homeowners notice a warmer, quieter and more comfortable interior. Estates and commercial buildings also gain long term asset value. Where building consent is required Crittall works closely with architects and planning authorities to ensure full compliance. 

Projects across the country demonstrate how both approaches can succeed. Crittall Windows  returned to Adelaide House in London to replace the steel windows it originally manufactured and fitted in 1925. The Grade II Listed building, located on the north bank of the Thames near London Bridge, required new windows that preserved its historic aesthetic while meeting strict planning requirements. Crittall selected double glazed Corporate® W20 EVO windows with 20mm insulated glass, which replicate the original sightlines and hardware but offer modern thermal performance. These new steel windows complement the extensive refurbishment of the riverside office block, combining century-old style with contemporary functionality. 

The architectural significance of a property deserves expert attention. Crittall has been manufacturing steel frames since 1849 and continues to support those responsible for preserving the United Kingdom’s built environment. The team can refurbish original frames or design new steel windows that match the original appearance. Every decision aims to protect what makes a building special, while ensuring it meets the standards expected today. 

• For more information on refurbishing and/or replacing steel windows, contact us here.