While window frames and timber cills are an individual repair, if they aren't properly maintained, they can cause damage to the common structure of the building. Close windows as well as lintels and stone cills that are part of the structure of the building are common repairs.

Window frames

Window frames, the moving parts of the window and the mastic that seals the frames in the wall are generally individual responsibility. Everything around this is generally a common repair.

Even though windows are an individual repair, you have a legal duty to maintain them. The main thing to do is prevent water trickling into the walls and causing rot.

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Defective puttyA simple task to fix and one that can save your windows. Putty should also be painted.

Window maintenance

Timber windows can be easily repaired, often at a cost much lower than replacing. Repairs are possible by installing new timber cills and splicing new timber into the sides of the case. Sash and case windows can also be dismantled and then draught stripped. Preventive maintenance is also simple.

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Rotten cill and broken masticJohn GilbertThe cill can be replaced and the window sash repaired. The mastic should be entirely renewed

Regular repainting. Timber cills and the bottom rail of windows will decay first and badly decayed cills can allow water in. Repaint timber and metal windows every five years or less in more exposed location.

Get the mastic around your windows checked every painting cycle. If it needs to be replaced, the traditional burnt sand and boiled linseed oil mastic lasts longer and retains its flexibility better than ordinary, trowel applied builders mastic. Polysulphide mastics applied with a gun are not good at filling large gaps and are best not used on stone buildings.

More information on the use of burnt sand mastic

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Defective window masticThis problem can let rain into your building's structure. Note also the butterfly hinge which allows the bottom sash to hook onto the hinge and open inwards for cleaning

"Simplex" fittings allow sash and case windows to be opened inwards for cleaning.  

It is worth joining with other owners to get all windows painted and the mastic repaired at the same time.

More on maintaining timber windows

Guide to Maintaining Traditional Sash and Case Windows

Around windows

The stone and brick in the walls around your windows are generally a common responsibility. The elements that require your attention are:

Lintels – supporting the walls above the window opening

Cills – need to shed water to help keep the walls below dry

Canopies, architraves and hoods are not just attractive – they help protect the windows from the weather.

Mullions – the vertical stones between windows

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Identical windowsJohn GilbertEnhancing the building

Replacing windows

Having everyone's windows the same style and painted in the same colours can greatly enhance the look and value of your home. Its a badge of quality, so it is worthwhile maintaining what you’ve got. 

And there is much that can be done to increase the energy efficiency of your existing windows.

Reducing Heat Loss from your Windows and Doors

If you do need to replace your windows, bear in mind that many Councils  have a planning policy on window replacement and require every flat owner to get planning consent to replace or alter windows. Check with your local council's Planning Department. You will certainly require listed building consent to replace your windows if your building is listed and if you are in a conservation area you will also need planning approval for window replacement work.

There are lots of regulations about window design, safe cleaning and cill heights.  If you are a landlord, or if you are carrying out major repairs, you may be asked to comply with these standards - check with your Council's Building Control team.

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Overhauled sash windowJohn GilbertThis window has had slimline double glazing added

Close windows - a common repair

Make sure you can open them to allow ventilation to the stair.  This can help prevent condensation occurring on the skylight. Repaint every 5 years or more often in exposed locations.

If you have stained glass windows or painted Victorian glass, then this should be conserved. It is possible to remove painted glass panels and sandwich them between toughened glass to give them more protection, however the weights to the sash would need to be adjusted.

Other types of windows

Oriel and Bay Windows

Dormer Windows


Professional help recommended?

Although the work may appear straightforward, ensure your builder or tradespeople have the skills for the job. If in any doubt, get professional help to specify and organise the repair.

Further information:

Historic Scotland Short Guide 'Sash and Case Windows: A Short Guide for Homeowners'

Historic Scotland Inform Guide 'Maintaining Sash and Case Windows'

Changeworks for Citizens Advice Scotland Factsheet 'Reducing Heat Loss From Your Windows and Doors'

Changeworks for Citizens Advice Scotland Factsheet 'Keeping out draughts'

Society for the Protection of Ancient Buildings Technical Q&A 'Upgrading Windows'