This short video shows the process of opening up and rebuilding a badly damaged traditional sash window. It demonstrates why extensive-looking damage does not always mean that the complete window must be replaced.

Box Frame Sash Window Repairs

Repairing Rotten and Damaged Sash Window Box Frames

The box frame is the main timber frame that holds the sash windows, pulleys, sash cords and weights.

Because much of the frame is hidden behind the internal linings, damage can sometimes become quite advanced before it is noticed.

Rotten timber does not always mean that the complete window needs to be replaced. In many cases, the damaged section of the box frame can be cut out and repaired while keeping the sound original timber in place.

I repair traditional timber box sash windows throughout Eastbourne and the surrounding areas of East Sussex.

Signs That a Sash Window Box Frame Needs Repair

You may have a problem with the box frame if:

• The timber feels soft or crumbles when touched

• Paint is bubbling, cracking or lifting

• There are visible gaps or splits in the frame

• Water is getting into the window

• The sash window has become loose or unstable

• The window no longer opens or closes correctly

• The lower corners or outer lining are rotten

• Previous filler repairs are beginning to fail

• Parts of the frame have been patched repeatedly

The full extent of the damage is not always visible until the window is opened up and examined properly.

What Causes Box Frame Rot?

Box frame damage is normally caused by water getting into the timber over a long period.

Common causes include:

• Failed paintwork

• Cracked or missing putty

• Open joints in the window frame

• Poorly fitted external repairs

• Water collecting around the sill

• Blocked drainage

• Leaking gutters or masonry above the window

• Old repairs made with unsuitable filler

• Timber being covered before it has properly dried

Once water gets behind the paint or into an open joint, it can remain trapped and gradually rot the timber.

How I Repair a Rotten Box Frame

I begin by opening up the window and carefully examining the damaged area.

Loose paint, filler and rotten timber are removed so that the true extent of the problem can be seen.

The repair may include:

• Removing the sash windows where necessary

• Opening the box frame to gain access

• Cutting out rotten or badly damaged timber

• Cleaning and treating the remaining sound timber

• Making new timber sections to match the original frame

• Splicing the new timber into the existing box frame

• Repairing damaged linings, pulley stiles or outer facings

• Checking the pulleys, cords and weights

• Reassembling and testing the window

• Priming and sealing the repaired timber

Each repair is different. I only remove the timber that genuinely needs to be removed.

The aim is to make a strong, practical repair while preserving as much of the original window as possible.

Repairing Previous Box Frame Repairs

Many old sash windows have already been repaired at some point.

Unfortunately, some repairs consist mainly of filler, pieces of timber nailed over the damage or sealant covering rotten wood.

These repairs may look acceptable for a short time, but they often trap moisture and eventually fail.

Where possible, I remove the failed repair, cut back to sound timber and rebuild the damaged section properly.

A sound timber repair should form part of the structure of the window rather than simply hiding the damage.

Repair Rather Than Replace

A rotten section of box frame does not automatically mean that the complete sash window needs replacing.

Traditional sash windows were made in separate timber sections. This means that damaged areas can often be repaired individually.

Repairing the existing window can:

• Preserve the original character of the building

• Retain old timber that is still perfectly sound

• Avoid unnecessary replacement

• Reduce disruption

• Maintain the proportions and appearance of the original window

• Be more economical than installing a complete new window

Replacement should normally be considered only when the window is beyond sensible repair.

Other Work That Can Be Carried Out at the Same Time

Once the box frame has been opened, it may be sensible to deal with any other problems that are found.

This can include:

• Renewing broken sash cords

• Repairing or replacing pulleys

• Rebalancing the sash weights

• Repairing rotten sash sections

• Replacing a rotten sill

• Freeing sticking sash windows

• Renewing parting and staff beads

• Draught proofing

• Replacing damaged glass

• Improving the general operation of the window

I will explain what is necessary before carrying out additional work.

Traditional Sash Window Repairs in East Sussex

I carry out box frame sash window repairs in:

• Eastbourne

• Pevensey

• Polegate

• Hailsham

• Seaford

• Lewes

• Bexhill

• Hastings

• Surrounding areas of East Sussex

For properties farther away, please contact me with photographs and details of the window.

Do You Have a Rotten or Damaged Sash Window Box Frame?

Send me a few clear photographs showing:

• The complete window

• The damaged section

• The outside of the window where possible

• Any cracked paint, open joints or visible rot

I can then give you an initial idea of what may be involved.

Contact RWJ Sear Restorative Carpentry

Traditional sash window repairs carried out with the aim of preserving and repairing the existing window wherever reasonably possible.