The Sash Window Workshop specialises in the replacement of timber sash windows; this is their classic timber multi-paned three-aspect bay, POA (01344 868668)
Windows and doors that are original or of historic interest make a major contribution to the style of traditional houses. Our general advice is that the proportions and details of these features should not be altered, as they are important elements of the design and character of the property.
Planning issues of replacing windows and doors
Many houses have Permitted Development rights which make it possible to replace existing windows and doors without requiring planning permission from the local authority, as long as the materials of the replacement windows are “of a similar appearance” to those used for the existing designs.
However, in the case of a listed building, any works to alter the building in a way that affects its character will require listed building consent from the local planning authority. One key area that building officers are keen to maintain is that the aesthetic integrity of the design of the building should not be compromised. Take advice from a reputable company which has experience in window and door design and construction, and remember that planning officers can also advise on what is and is not acceptable.
Fixed bronze casement windows complement this medieval barn. From £330 for a 550mm x 1,200mm casement, by Architectural Bronze Casements
To gain permission to replace any listed windows or doors, homeowners need to prove that the existing ones are beyond repair or that they are experiencing too much heat loss. Energy is lost through windows in two ways: by heat passing through the glass and by warm air escaping though gaps in and around the frames. Consequently, glazing can sometimes be an issue on a period property when original windows feature single-glazed units.
White uPVC cottage style French doors and windows by Everest; double-glazed, with the option of triple glazing, as well as decorative coloured, leaded and beveled options, prices are on application
Impact on design
Traditionally, windows used fine glazing bars to hold the small panes of glass in place, but with double-glazed units the bars need to be wider to hold the weight. Specialist window companies can provide design solutions for this and innovations in glazing have helped too. The thickness of double glazing can be varied with the use of energy efficient gasses. To meet building regulations the amount of heat that can pass through the glass and framework is measured as a U-value and this has an effect on the efficiency of the window. For a listed building there is some flexibility in the U-value, in the interest of preserving traditional character.
Bespoke Benenden aluminum windows are extremely slim, and can be fitted within existing timber frames, or brick or stone surrounds. Prices on application, The Heritage Window Company
Original windows with leaded “lights” can date back as far as the 15th century, so if you are lucky enough to be the owner of such windows, be prepared to repair and restore them to keep them in good order and wind and watertight. Glass was costly in those times and was only produced in small pieces – usually rectangles or diamonds, which were joined together with strips of lead. As each piece of glass was slightly different and not as perfect as the factory produced glass we are accustomed to now, each pane would be slightly angled and pitted, causing reflections to be thrown at different angles, and adding unique character. Listed buildings with leaded lights will need specialist repair or renovation, using matched materials.
Single glazed steel-frame windows with leaded lights, from about £4,200 for a six-bay layout, including three side-hung and three fixed lights, each measuring around 500mm x 1500mm, by Clement Windows