We use a variety of different double glazed units to suit the individual specification for our sash windows. We can make windows to suit any thickness of double glazed units, however an overall thickness of around 18mm is about the maximum you can fit before it starts to look a lot thicker than a traditional sash and case window.
For double glazed sashes in listed buildings and conservation areas, a slimline unit is often stipulated. This would normally be a 14mm, 4/6/4, argon gas filled unit, with a warm edge spacer bar for energy efficiency and low emissivity glass for the internal pane.
If the bottom panes are less than 800mm from floor level, these will need to be safety glass.
We have adjusted the profiles of our sashes to allow us the maximum detail possible to the timber moulding, as well as the maximum energy efficiency. Sash and case windows are a traditional design and it has always been our company’s aim to keep them as traditional looking as possible.
Our windows are manufactured with haunched tenons to allow for the additional weight in a double glazed unit and often our top sashes have an ornate horned detail. The horn on the upper sash is a traditional detail to give strength to the upper sash in large windows (see picture to right).
To the eye our windows match almost exactly the look of the original single glazed sash.
Upgrading sash windows to double glazing
If you are considering fitting double glazed sash and case windows into your property, it is not always necessary to replace the complete window.
If you already have sash and case windows and your existing casement is in good condition, we can manufacture new sashes to fit exactly into the existing box.
This means there is no need to remove panelling and shuttering and offers considerable savings over complete replacement. The case is carefully renovated, the external pointing is renewed, and the windows are fully draught proofed.
Click on the Grange Terrace case study for complete information on the process including before and after gallery.
Q. Can I install double glazed sash windows in my property?
A. For listed buildings there is no simple answer, but for most other properties it is not a problem. For listed buildings a listed building application form will be required to be submitted along with drawings, photos and a condition report. We work with a chartered architect who specialises in the listed building process who can help you with your application if required.
A phone call to the local planning authority will clarify your listed status.