Secondary glazing for stone mullion windows

We have developed CosyGlazing, an expertly crafted, bespoke secondary glazing solution for stone mullion windows.

As specialists in insulating period and listed properties, we have developed insulation solutions for all types of windows that give thermal efficiency to improve warmth and comfort, and reduce energy costs, whilst also working with the aesthetic beauty of the heritage of the building. One such solution we have developed is an expertly crafted secondary glazing for stone mullion windows. 

We fit bespoke timber beading into the window reveal – hand-crafted and detailed so that it is discreet and fits with the character of the building. The beading is colour-matched to the reveal (bare or oiled oak looks perfect with traditional stone reveals or it can be painted to match). The timber beading provides a flat surface for the CosyGlazing to be fitted to. Units can be unframed (black tape works very well with black metal windows) or fitted with a colour-matched trim to match with the window or reveal so that the CosyGlazing is virtually invisible.

We try to design the solution so that the distance between the CosyGlazing and original glass is minimal to maximise thermal efficiency – or engineer a larger gap if soundproofing is the priority.

Some of our stone mullion window restoration projects

Benefits of CosyGlazing for stone mullion windows

• Our CosyGlazing is a completely bespoke, hand-crafted solution – tailored specifically for your stone mullion windows.
• The CosyGlazing system is reversible. There are no mechanical fixings into the building fabric.
• Draughts are kept in behind the CosyGlazing units, achieving approximately 70% heat loss saving.
• CosyGlazing units are fitted on magnetic tape, so they can be easily removed for ventilation, cleaning, decoration.
• Out of square reveals and windows are our specialty! Our solution is completely different from traditional secondary glazing, which is fitted square and the trims applied to make up the wonky shape.
• We can scribe beads so that they work with undulations of stone or around original hardware. We can also undertake small stone-work repairs or work with specialists to ensure surfaces are ready for our installation.

If you’d like to find out more about our CosyGlazing secondary glazing solution, see our FAQs page.