We provide glass replacement for traditional timber sash windows and casement windows. Ultra-slim double-glazing provides superb performance, while retaining the elegance of the original windows.
The double-glazed sealed units we install are only 12mm thick, so they usually fit comfortably in a single glazing aperture without the need to alter the timber.
Our expert window restorers carry out all the work on site – so it’s quick, economical and causes minimal disruption.
All our sash window glass replacement work comes with the maximum 5-year guarantee.
Diagram of glazing cross section
This cross section shows the construction of our sash window replacement glass units.
Two panes of 4mm glass are filled with a heavy gas, which aids acoustic performance.
The inner pane is a Low-E glass, which reflects heat back into the room.
A Warm Edge spacer bar (shown in black in the diagram) helps to reduce perimeter condensation.
We always install the sealed units with 6mm beading to ensure good weather deflection and to preserve the life of the window for many years.
Classic Heritage slim units are available incorporating a range of period glasses to closely replicate the aesthetics of the original glass.
The gap between the glass panes is filled with heavy gases, typically Krypton or a Krypton/Xenon mix. This gives a much better acoustic performance than standard Argon-filled units.
The 12mm sealed units we typically install give a 31 dB Rw acoustic rating. Specialist acoustic glazing units are also available, which provide up to 38 dB Rw sound reduction. Please ask us for details.
Thermal performance is strong, with typical 12mm units offering a U-value of 1.9 W/m²K.
Lower U-values (to 1.3 W/m²K) are available for units with larger cavities or thicker glass. Please ask us for details.
Glass in sash and casement windows is traditionally sealed with linseed oil putty. However, as this dries it becomes brittle and pulls away from the frame, allowing water ingress and premature damage to timber and paint.
To enhance appearance and longevity we use an elastic sealing compound, Repair Care Dry Seal™ MP. This has superb elasticity, even after years in situ. It comes in a choice of finishes and can be overpainted. The result is a superior, long-lasting, effective seal which will protect the window for years to come.
Get in touch to ask us about glass replacement on your next project.