Heritage Sash Window Replacements — A Portfolio

The brief

Replace failed or single-glazed sash windows in period properties with new thermally-broken sash units that match the original sightlines, retain authentic features (horn detailing, glazing bar layouts, sash horns and pulleys), and deliver modern double or triple-glazed performance. Some installations include acoustic-grade laminated glass for properties on busy roads or under flight paths.

Our approach

Every period sash project starts with a detailed survey: we measure the existing unit, photograph the surrounding architectural details, identify any conservation-area or listed-building constraints, and confirm the heritage specifications (glazing bar widths, sash horn profiles, paint finishes, ironmongery style). Our timber sash units are then manufactured to match. Installation typically takes one or two days per window, working through the property elevation by elevation.

Outcomes

• Period character preserved to conservation-officer standards
• Whole-window U-values from 1.3 W/m²K (a 70% improvement over single glazing)
• Acoustic improvement: typically 35-42 dB Rw with laminated specifications
• Conservation-area approvals achieved on every project to date

"The new sashes are indistinguishable from the originals at first glance. The thermal upgrade is dramatic — our heating bills have dropped considerably and the noise reduction is the unexpected bonus."

— Listed-building owner, Cotswolds