Caring for your sash and case windows.

A quick check once a year

Historic Environment Scotland recommends regular inspections, and cleaning the glass and timber is a good time to do one. Look for:

• Paint that is cracked, flaking or worn through to bare wood, especially on the sill and bottom rail.
• Putty that is cracked, loose or missing around the glass.
• Cords that are frayed, thin or stiff where they run over the pulleys.
• Soft timber. Rot is not always visible. Press a penknife into any suspect wood: sound timber resists the blade, decayed timber does not.
• A musty smell inside the weight box, which can mean damp and the start of decay.
• Gaps and draughts around the sashes, and sashes that rattle or stick.
• Pointing between the case and the stonework that has cracked or come away.

Painting

External paintwork protects the timber from the weather, and internal paintwork protects it from condensation. Historic Environment Scotland says windows usually need repainting outside about every five years, depending on how exposed they are and the paint used. Our microporous paint has a life of up to 14 years, but a sheltered window lasts longer than one facing the prevailing weather.

• Paint in thin coats, and follow the right order so the sashes are not painted shut.
• Do not paint the edges where the sashes slide, or the cords.
• Do not paint over the mastic pointing between the case and the stone.
• Move the sashes up and down once the paint is dry so they do not stick.

Putty

Putty hardens and cracks when the paint over it fails, and then lets water in behind the glass. Small repairs should be made with traditional linseed oil putty and painted once it has skinned over.

Sash cords

Cotton sash cords wear out over time. They are best renewed before they break, when the weights are still easy to reach. If a sash suddenly drops or will not stay open, a cord has probably gone: keep the window closed and call us rather than propping it.

Sills and rot

The sill is usually the part most prone to decay. Caught early, a rotten sill can often be repaired by splicing in new timber or renewing just the front section, rather than replacing the whole window. See restore or replace?

Everyday use

• Open and close every window from time to time, including ones you rarely use, so they keep running freely.
• Open the top sash a little to ventilate a room, which helps reduce condensation.
• Wipe away condensation from sills and glass in cold weather so it does not soak into the timber.
• If you have simplex fittings, use them to clean the outside of upper floor windows safely from indoors.

Jobs to leave to a joiner

Replacing cords and balancing weights, splicing in new timber, reglazing, repointing and fitting draught proofing all need the window taking apart and are best done by someone who knows sash windows. In a listed building, using the right materials also keeps you within the rules. See our listed building guide.