A sash window can look sound while small problems develop around the sill, putty, cords, or paint joints. London’s weather and the effects of condensation make a regular check worthwhile.
Inspect timber sash windows once a year, ideally in spring, with a shorter testing before winter. Here is what to examine, what you can safely handle, and when to seek professional help.
Need help assessing a problem?
If a window is sticking, showing soft timber, or no longer staying open, do not force it. The London Sash Window Company can assess whether targeted sash window repairs are enough before you decide what to do. Call 020 8017 1632 or email office@londonsash.com.
The best time to deal with a sash window problem is when it is still a small change in paint, movement, or sealing, not after water or repeated strain has spread the damage.
Your annual timber sash window maintenance checklist
Choose a dry day, work from outside to inside, and open and close each sash gently.
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Check paintwork and exposed timber
Inspect sills, lower rails, frame joints, and places where rainwater may sit. Look for peeling, blistering, cracks, bare timber, dark staining, or wood that feels soft when pressed gently.
Prepare and repaint small defects before water reaches the timber. Do not coat over damp, loose paint, or decay. Good care for wooden sash windows also means keeping sill edges and drainage paths clear.
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Inspect glazing putty
Putty seals the gap between glass and timber. Check for cracks, gaps, crumbling edges, loose sections, moving glass, or water marks below the pane.
Minor cracking may be repairable, but loose glass, widespread failure, or decayed glazing bars need skilled attention. Avoid sealants not designed for traditional timber windows.
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Test cords, weights, and movement
Open each sash slowly. It should move evenly, stay at the chosen height, and close without dropping or twisting. Frayed cords, scraping, a falling sash, or one side sitting lower can indicate cord, pulley, or counterweight trouble.
Never place fingers beneath an unsupported sash. This sash window annual check is observational, not a reason to dismantle the box frame.
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Examine draught seals and meeting rails
Brush seals can wear, flatten, loosen, or clog with paint and dust. Close the window and check for visible gaps, rattling, or draughts around the meeting rails and sides.
Do not caulk every gap. Sashes need clearance to move, and permanent ventilation must remain open. Effective sash window upkeep balances draught reduction, movement, and airflow.
A simple seasonal routine
In spring, clean the frames, inspect paint and putty, and test operation. Summer is usually best for dry-weather painting and joinery repairs. In autumn, clear debris, check seals and catches, and make sure windows close securely. During winter, wipe away condensation and note recurring cold spots or leaks.
Use a soft cloth and mild detergent. Avoid abrasives, pressure washing, and soaking joints. Follow installer or coating instructions first.
Prevent condensation without blocking ventilation
Condensation forms when moist indoor air meets a cold surface. Regular droplets or pooled water can damage paint and encourage timber deterioration.
Use kitchen and bathroom extractors, keep background vents open, air rooms regularly, and wipe water from glass and timber. In warmer weather, opening both sash sections supports airflow. In colder conditions, a smaller upper opening can ventilate more comfortably.
Persistent condensation may indicate poor ventilation, failed seals, leaks, or another damp source. Draught-proofing should not prevent moisture escaping.
When should you call a sash window professional?
Seek advice for soft or crumbling timber, extensive putty failure, loose glass, broken cords, faulty weights, water entry, or a sash that will not remain safely open. Repeated sticking can indicate swelling, paint build-up, distortion, or balance problems.
Repair is often proportionate when sound original timber remains. The right approach depends on decay, previous alterations, access, and heritage restrictions.
For ongoing care, our sash window aftercare guidance covers cleaning, inspection, and smooth operation.
A yearly check protects character and function
A spring inspection, timely paint and putty repairs, safe testing of cords and weights, and sensible condensation control will reveal most developing issues.
Keep dated notes and photographs for each window. Year-to-year comparisons make subtle changes easier to spot and give a repair specialist useful context.
Talk through your window’s condition
For advice on a sticking, draughty, damaged, or deteriorating sash window, call The London Sash Window Company on 020 8017 1632 or email office@londonsash.com. Our team can explain whether maintenance, repair, or a wider overhaul is appropriate.
Frequently asked questions
How often should timber sash windows be maintained?
Inspect them thoroughly once a year and briefly before winter. Exposed windows or those with previous repairs may need more frequent checks.
How often do timber sash windows need painting?
There is no fixed interval. Repaint when coatings crack, thin, or expose timber, following the paint manufacturer’s preparation guidance.
Can I replace a sash cord myself?
It is possible, but the sash is heavy and the box frame must be opened correctly. Professional repair is safer without suitable tools or experience.
Why does my sash window keep sticking?
Common causes include paint build-up, dirt, timber swelling, damaged cords, misalignment, or distortion. Do not force it, as this may strain joints and fittings.
Is condensation a sign that the window has failed?
Not necessarily. It often reflects indoor moisture, cold surfaces, and limited ventilation, although persistent problems deserve investigation.