On this page:

  1. Introduction
  2. What repairs and maintenance might be needed?
  3. What thermal improvements can I make?
  4. Do I need Listed Building Consent for works to windows?
  5. Contact us

Windows - an introduction

Old windows are key to the appearance and function of a historic building, and contribute to its heritage value and significance. They are also evidence of traditional craft skills, which have been replaced by modern, industrial materials and processes.

What repairs and maintenance might be needed?

The paint, putty beads and any moving parts of old windows will need regular attention. The replacement of a window will only be considered as an option when repairs are no longer possible.

The timber of pre-1900 windows should be very durable, and is unlikely to need more than splice or patch repairs by a joiner. Spliced repairs should be designed so that water is directed toward the outer face of the timber, and made from good-quality wood similar to the existing species - and with the grain orientated to match the existing. Any new sections of timber should also be shaped to match the existing, using the historic frame as a pattern. Timber sills are especially vulnerable to rot and if replaced, should be replaced with oak or another durable native hardwood.

For metal windows, it is important to first identify the type of metal used to establish the correct approach. Ferrous metals such as iron and steel are magnetic, whereas non-ferrous such as bronze and aluminium or not. It may also be important to consider the method of manufacture as wrought and cast iron also have different properties. Ferrous metal windows can suffer from surface rust, distortion, excessive build-up of paint and failed hinges and fittings.  Rust and paint can be removed by acid pickling or flame cleaning. Any necessary repairs to wrought iron or steel windows, including welding in replacement sections, can be made by a professional metalworker. Cast iron windows cannot generally be welded because they tend to crack when heated, but they can be repaired using a technique known as ‘cold stitching’. Non-ferrous frames can be repaired by brazing, soldering and welding.

The glass itself in historic windows often greatly contributes to their significance. Historic crown or cylinder glass, which often has characteristic distortions or bubbles across its surface, should always be retained and reused where possible. Other historic glasses include polished plate glass or drawn glass, early machine made glass and stained, painted, etched or other decorative glass. Where replacement is required, matching modern glass should be used rather than plain float glass.

Whenever possible the original fixtures and fittings of historic windows (hinges, catches, pulleys, handles, stays etc) should be kept for refurbishment and re-use on the window being repaired.

What thermal improvements can I make?

The thermal performance of windows can be considerably improved by a range of low-cost and low-impact measures including draught-proofing, curtains, blinds, internal shutters, and secondary glazing. These measures usually do not need Listed Building Consent. Good maintenance will also improve the thermal efficiency of windows.

For more information on thermal improvements across historic buildings, please read our energy efficiency in historic buildings guidance.

You will need to obtain Listed Building Consent before replacing any window in any part of a Listed Building – this includes modern windows. You may also need Listed Building Consent if window repairs involve losing substantial amounts of old material. Replacing plain panes of modern float glass is also unlikely to require Listed Building Consent.

Any application should identify which windows are to be replaced and should show (through drawings) any changes in the size or shape of the window opening, and any changes to the window design.

Detailed section drawings of the joinery will also be needed. These can be included in the application itself, but are otherwise required through a Condition attached to the Listed Building Consent. The section drawings should show the fabric around the window (to explain how the window will appear when installed), how the glass is fixed, how the window opens, and the applied finish (including colour).

If the existing window is historic then the only acceptable replacement is an exact replica, matching the design, construction, materials, details, and finish of the existing. Old, surviving glass should be carefully removed and reused.

If the existing window is an inappropriate modern window, the replacement window will need to enhance the building’s heritage value by emulating the design, materials and finish of a suitable historic example. Slimline double-glazed units can be used in a window of traditional design to replace a modern window.

Have another question? Contact us

If you haven't found the information you were looking for on this webpage, please read our Windows in historic and listed buildings guidance (which covers this topic much more extensively).

If you still need further advice, please contact our Heritage team.

Email heritage@baberghmidsuffolk.gov.uk

Phone 0300 123 4000 (Option 5, then Option 3)

Write to us:

Heritage Team

Babergh and Mid Suffolk District Councils

8 Russell Road

Ipswich

IP1 2BX