Can you double glaze traditional style timber windows?

Replacing the windows in your property represents a substantial investment which requires a great deal of thought and extensive research.  Window openings and frames are an integral part of the design of a building, giving it character and proportion and inappropriate replacements can be very damaging to the overall appearance of a building.  However, new windows can transform the appearance, security and comfort of your home and, if accomplished with sensitivity and understanding, can represent a significant improvement which can increase the value of your property.

Wood has been the natural choice for windows for centuries and there are many excellent examples of wooden windows which are over 100 years old and still perfectly serviceable today. Wood is a natural renewable resource and, when adequately and appropriately maintained, can give many years of useful service.  Wooden windows can be repaired and renovated to extend their lifetime but, inevitably, they can reach the point where they are beyond repair and require replacement at which time it may be possible to incorporate modern technology to upgrade their performance whilst maintaining the aesthetic appearance of the originals.

Both casement and traditional sliding sash windows can be fitted with double glazing.  If there are no fine glazing bars in the original design, 24mm units can be incorporated within replacements which replicate the original features and, in sliding sash windows, can be combined with traditional sash weights and cord.  If the window requires fine glazing bars 24mm double glazed units can have inset spacer bar and applied glazing bars to the exterior of the unit to give the appearance of individual panes of glass.  Alternatively, slimmer double glazed units can be used in traditional style Georgian and Victorian type designs enabling the glazing bars and section sizes to replicate the slimmer appearance of the original windows.

Double glazing works by trapping air between two panes of glass creating an insulating barrier that reduces heat loss, noise and condensation.  The sealed units usually consist of two panes of glass vacuum sealed into a single unit that is fitted into the window frame.  The thermal performance, or U-value of a replacement window, can be increased by upgrading the glass type, the gap between the sheets of glass, filling the cavity with gas or adding sheets of glass, ie triple glazing.

Replacement windows – get good advice

If your property is located within a Conservation area it is wise to seek advice from your local Conservation or Planning Officer before obtaining a quotation to replace your windows.  They will be able to tell you whether double glazed replacements are likely to gain their approval for the type of property in its particular location.  Replacement windows in Listed Properties will always require Listed Building Consent unless the replacements are like-for-like and single glazed.  If single glazing is stipulated, a specialist joinery manufacturer and installer can replicate the design of the original windows to incorporate draught strip for added insulation which can be combined with additional methods of thermal insulation including secondary glazing, shutters and the use of curtains with thermal lining.