The honest answer is: it depends on what is wrong with the window.
A simple sash cord replacement is very different from a full restoration involving rotten timber, sill repairs, draught-proofing, repainting and rebalancing.
The cost depends on things like:

• how many windows need work

• whether the sashes come out easily

• whether there is hidden rot

• whether the sill or lower rails need repairing

• whether the window needs draught-proofing

• how much old paint has built up over the years

I prefer to look at the actual window and give a proper assessment rather than throw out a silly guess. Old sash windows can hide all sorts of surprises, especially once the paint is removed.

My approach is straightforward: I explain what I can see, what may be hidden, what needs doing now, and what can wait.

Sash windows become draughty because they are moving windows with gaps around them.

Over the years, timber shrinks, paint builds up, parting beads wear, staff beads become loose, and the sashes stop fitting as tightly as they once did. Sometimes the window has simply been neglected for too long.

The good news is that draughts do not automatically mean the window needs replacing.

In many cases, the sashes can be removed, eased, repaired, re-corded if needed, and fitted with discreet draught-proofing. This can make a huge difference to comfort without spoiling the look of the original window.

A properly repaired and draught-proofed sash window should still look like a traditional sash window — just warmer, quieter and easier to use.

Yes, they can.

Draught-proofing and double glazing are not the same thing. A lot of heat and comfort is lost through gaps, rattles and air movement around the sashes. You can often make a big improvement by dealing with those gaps properly.

Draught-proofing usually involves removing the sashes, checking the condition of the cords and weights, easing the window, and fitting brush seals into the correct places.

It will not turn an old sash window into a modern sealed unit, but it can make the room feel far more comfortable and reduce rattling, dust and cold air.

For many older homes in Eastbourne, especially period houses, this is often a very sensible first step before thinking about more drastic changes.

Sash cords break because they are doing a lot of work.

Every time you open and close a sash window, the cords are carrying the weight of the sash. Over many years they wear, fray, stretch, and eventually snap.

Sometimes the pulley is stiff or worn, which puts extra strain on the cord. Sometimes old paint, dirt or swelling timber makes the sash hard to move, so the cord is forced to work harder than it should.

When a cord breaks, the sash may drop suddenly, become very heavy, or refuse to stay open.

Replacing sash cords is a normal part of maintaining traditional sash windows. When I do it, I also like to check the pulleys, weights and general movement of the window, because there is usually a reason the cord has failed.

Rattling sash windows are usually caused by loose fitting sashes, worn beads, gaps around the frame, or missing draught-proofing.

The window is moving slightly in the wind because it is no longer held firmly in place.

The answer is not to just jam it tight or paint it shut. That only creates another problem.

The proper way is to remove or adjust the beads, check how the sashes are sitting, make sure the window can still slide properly, and fit suitable draught-proofing where needed.

Done properly, the window should still open and close, but without the annoying rattle every time the wind gets up.

This is one of those jobs where small details matter. Too tight, and the window sticks. Too loose, and it rattles. The trick is getting the balance right.

Restoring a sash window is not one single job.
It is a series of careful steps.

Depending on the condition of the window, it may involve removing the sashes, cutting through old paint, taking off staff beads, checking the cords and weights, repairing rotten timber, replacing loose putty, sanding, easing, priming, painting, draught-proofing and rebalancing.

Some windows only need light attention. Others need proper surgery.

The important thing is not to rush in blindly. Old sash windows often reveal their problems as they are opened up. Paint can hide rot. A sash that looks fine from the outside may have a rotten bottom rail. A sill may look tired but still be repairable.

My aim is always to keep as much original material as possible while making the window usable, sound and beautiful again.

Yes, many rotten sills can be repaired, but it depends how far the rot has gone.

A small amount of decay can often be cut out and repaired. If the sill is badly gone, it may need a more serious timber repair or partial replacement.

The important thing is to remove the rotten material properly and understand why it happened in the first place. There is no point making a repair if water is still being trapped in the same place.

Rotten sills are very common on older sash windows because they take the brunt of the weather. Paint cracks, water gets in, and over time the timber starts to break down.

A good sill repair should be solid, weather-resistant, properly shaped, and finished so water is encouraged to run off rather than sit there.

Yes, very often they can.

In fact, many old sash windows are far better made than modern replacements. If the main timber is still sound, it is usually worth repairing them rather than ripping them out.

Most of the problems I see are things like broken sash cords, windows painted shut, loose putty, rattles, draughts, rotten sills, or sashes that no longer run properly. These are all repairable problems.

A good repair keeps the character of the house, keeps the original timber, and often saves a perfectly good window from being thrown away unnecessarily.

I repair and restore traditional sash windows in Eastbourne and across East Sussex, and my first thought is always: what can be saved?