Window Woman guides

Understanding windows & doors

Repair or replace?

Conservation works on a simple principle: keep as much of the original as possible, and change only what's necessary.

Historic windows and doors carry the building's history in their timber, glass and joints. Once they're gone, that can't be put back.

The good news is that old timber, often slow-grown and dense, is frequently better than new. Many windows that look past saving are not.

What can usually be repaired

• Rotten sills and lower rails, by splicing in new timber
• Broken sash cords, by re-cording
• Sticking or rattling sashes, by easing, adjusting and re-beading
• Loose or cracked putty, by re-puttying with linseed oil putty
• Failing joints, by re-gluing and pinning
• Draughts, with brush seals discreetly routed into the beads

When replacement may be justified

• The window or door is already a modern replacement
• Decay is so extensive that little original material remains

Even then, the new window or door should be a faithful copy in materials, profiles and detail. Bear in mind that replacing a whole window in a listed building usually needs consent, even with an exact copy; the FAQ explains why.

Timber and paint

Historic softwood was often slow-grown Baltic pine, dense and resinous, and many windows made from it are 150 years old or more and still sound. Modern softwood is faster-grown and less durable unless carefully specified; oak and modified timbers such as Accoya are good choices for new work.

Traditional linseed oil paint is flexible, lets the timber breathe and can be recoated without stripping. Many historic windows were not white: off-whites, stone colours, greys and dark greens all have a long history.

These guides are general information for England and don't replace advice specific to your property or your local planning authority.