Vertical-sliding sash window

The traditional timber vertical-sliding sash window remains one of the most characteristic and popular features of English buildings, particularly residential buildings.

It is the outcome of craftsmanship, manufacturing ingenuity and social changes – a sophisticated, well mannered and carefully detailed practical component produced in thousands within a very narrow range of details. Earlier versions may not now meet the current Part L regulations or preferred standards regarding draughts, thermal insulation, energy saving or sound reduction, but they do provide a very positive character to buildings.

In many areas this type of window not only forms a crucial part of the design of the building; it also helps to unify urban settings that have otherwise differing architectural styles and detail.

Good original details are difficult to replicate Good original details are difficult to replicate
Replacement UPVC window Replacement UPVC window -
  subtly obtrusive, scant respect for   appearance or the mechanics of   sashes

To date, only timber has provided the required detailing and visual quality. Other materials, such as PVC-U and aluminium, often degrade the character and architectural integrity of a building. When used sporadically, they destroy the unity of the urban setting.

Claims that PVC-U windows reduce maintenance are often exaggerated, and the lifespan of many existing vertical-sliding sash timber windows is witness to their potential longevity. The original construction of the sash window has no inherent defects, and lends itself to modern repair techniques. Therefore, it is better to repair original sash windows rather than replace them. Cost-effective upgrades can be achieved using benign alternatives to complete replacement.

Good and attractive original window set
Good and attractive original window set
Unsympathetic window replacement with loss of surrounding detail
....compared to a particularly   unsympathetic window replacement with   loss of surrounding detail

If it is necessary to replace existing vertical-sliding sash windows in listed buildings, conservation areas and other sensitive situations, replacements should match the original proportions and profiles. Exact reproduction is possible through a bespoke service. Alternatively, many traditional designs are still available as mass-produced items, and several companies can replicate traditional detailing whilst accommodating double-glazing.

PVC-U windows can be acceptable if they accommodate the size and detail of the section profiles and the jointing methods, and if they match the context of the building into which they are to be placed.

We would not normally approve of PVC-U windows in older style properties.

We would also object to the rear or sides of buildings being treated differently from the front, unless the faces cannot be seen together and they have little or no impact on the conservation area.