Replacing Windows in a Conservation Area

Replacing Windows in a Conservation Area used to be an arduous task. The fenestration industry has developed significantly in recent years, widening the options when replacing historic windows and improving their performance.

Replacing Windows in a Conservation Area

Many projects, whether refurbishment, extension or newbuild, may involve repairing replacing or replication historic windows. The process of assessing existing window and door conditions and needs, the options for repair or replacement, the challenges and considerations involved and the technical capabilities of the industry are all important factors in meeting conservation requirements.

Replacement Conservation Windows

Meeting typical conservation Requirements

Evaluating and planning the repair and replacement of windows on historic building and in conservation areas can be a complex process involving both objective and subjective considerations. Determining the architectural and historical significance of the windows, with reference to local and national planning regulations and guidance is the first step. If the windows are determined to be of historical significance, repair or rehabilitations is generally considered preferable to replacement. However many factors contribute to window deterioration, including poor design, moisture, vandalism, insects and lack of maintenance.

To Repair or To Replace Windows

The architectural integrity of existing windows can be assessed by mapping out the condition of each window unit, either using photographs or by listing the condition of each component. An assessment should include: window location, condition of the frame and sill, condition of the sash including rails, stiles and muntins, condition of the paint, any glazing problems, hardware condition and overall condition of the window rated as excellent, fair or poor.

Window Repair Classes

Generally the actions necessary to return a window to “like new” condition will fall into three categories which represent increasing difficulty, expense and time.
Repair Class I includes routine maintenance procedures
Repair Class II includes structural stabilisation
Repair Class III includes parts replacement.

Advantages of Window Replacement

Conservation principals dictate that the retention to the original materials and features is always preferable to replacement. However, if deterioration is expensive enough to warrant partial or full replacement, there can be advantages. In a building with a large number of windows, it may be more cost effective to replace rather than to repair deteriorated units. Also, in the interest of long term maintenance and energy usage, it may be preferable to match the look if not the materials of the original unit as oppose to repairing it. The use of aluminium and other materials has become more acceptable when original profiles can be replicated. This can allow for greater weatherability. Replacement can also take advantage of developments in glazing that have made windows more energy efficient

Historic Windows: Repair or Replace? Guidelines

We've prepared these guidelines to provide you with more information on repairing vs replacing windows in conservation areas


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