Aluminium Secondary Glazing Installation

A residential flat within a listed building in Chelsea required a solution to address significant heat loss and external noise without altering the building’s historic fabric. The original timber sash and casement windows were protected and could not be replaced, removed, or modified in any way. The residents were facing high energy bills and persistent cold, with secondary glazing identified as the only viable option. The goal was to install internal aluminium secondary glazing that would dramatically improve thermal insulation and acoustic performance while remaining fully reversible and visually discreet.

Our Solution

We supplied and installed bespoke aluminium secondary glazing fitted internally behind the original sash and casement windows. Secondary glazing is a recognised and often preferred solution for listed buildings and conservation areas, as it creates a thermal buffer zone without affecting the external appearance of the property or the historic joinery. The solution included:

• Slim-profile aluminium frames finished in white (RAL 9010) to blend discreetly with the original window reveals and internal décor
• Independent frame construction—the secondary glazing is fixed to the internal reveal, not to the original windows, ensuring zero intervention with the historic fabric
• Fully reversible installation allowing complete removal and reinstatement without damage to the listed structure
• Double-glazed sealed units with low-E coating and argon gas fill, creating an insulating air gap between the secondary glazing and original window
• Acoustic-grade glazing to significantly reduce traffic and city noise from the Chelsea street below
• Sliding and hinged opening configurations to allow access to the original windows for ventilation and operation
• Matching white handles and hardware for a clean, cohesive appearance
• Brush and compression seals around all frame perimeters to eliminate draughts and prevent air infiltration
• Concealed trickle vents where required to maintain background ventilation and prevent condensation between the glazing layers

Installation Process

• Conducted a detailed site survey with precision laser measurements of every window opening
• Reviewed the building’s listed status and liaised with the freeholder and managing agent regarding the proposed specification
• Confirmed the installation would have no impact on the external appearance or historic fabric of the building
• Completed all necessary paperwork, method statements, and risk assessments prior to commencement
• Protected all internal floors, furnishings, and window reveals before work began
• Inspected the original sash and casement windows, ensuring they were left entirely untouched and functional
• Prepared the internal reveals, ensuring surfaces were clean, level, and suitable for frame fixing
• Fixed slim aluminium sub-frames to the internal reveal using mechanical fixings, positioned to avoid interference with the original timber frames
• Lifted secondary glazing frames into position using precision packers and laser levels for perfect alignment
• Fitted double-glazed sealed units into each frame
• Installed sliding or hinged opening mechanisms and adjusted for smooth operation
• Applied compression and brush seals around all perimeters to eliminate draughts
• Fitted trickle vents where required to maintain ventilation and prevent interstitial condensation
• Tested operation of all opening sections and confirmed access to original windows was fully maintained
• Completed thorough clean of all glass, frames, reveals, and surrounding areas
• Conducted a final walkthrough with the residents to confirm satisfaction and demonstrate operation