Repair rotten wood windows

Sash Window Repair

For Over 20 Years We Have Been Repairing Sash Windows, Casement Windows and Period Doors.

Period timber windows and doors can almost always be repaired and restored. 

Our sash window repair service can repair sash windows, casements and Period doors more economically than replacing them.

  • Repair rotten windows. 
  • Replace sash cords or spring balances. 
  • Replace broken glass

For over 20 years we have been providing expert sash window repair.

Repairing a heritage window is the best way to preserve the character and architectural significance of a period home.

We have repaired and restored to good working order many old windows that our customers had thought to be beyond repair.   We can replace rotten window sills, rebuild rotten bay windows, repair rotten wood, renew broken sash window cords as well as replace broken glass.

Unaltered Appearance

Repairing traditional windows will ensure the original charm of your heritage home remains unaltered.

Long Life

Our window repairs are permanent fixes not patch up jobs. We use the latest advanced materials such as epoxy resin and Accoya wood.


Our specialist knowledge allows us to repair any timber window or door.

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Replace or repair old sash windows?


The timber used in the past was slow growth, high quality durable wood that should be preserved whenever possible. The quality of this old timber is why so many heritage windows and doors are still in use today.  Unfortunately many of the modern replacement timber windows on the market today may need replacement after only twenty years or so.

Victorian sash windows often feature ornate timber moulding that are very costly to replicate.  Repairing your windows will ensure that these fine details are preserved, retaining the charm of your period property.


How We Repair Wooden Windows


Repair Heritage Windows & Doors 2Wood rot is the most common problem associated with  period windows and doors.  Failure of the paintwork or glazing putty allows water to penetrate the wood, creating the ideal conditions for wet rot or insect attack.

We utilise a range of products during our sash window repair and restoration projects.  Time proven traditional repair methods of cutting out rotten wood and splicing in new timber are greatly improved after being bonded with modern products, such as epoxy resins and glues.  Our repair work is of the highest possible standard to ensure that we create a permanent, long lasting repair.


Repair Sash Window Counter Balance System

Sash Cords & Sash Chains

Sash window pulley with new sash cord.Replacing snapped sash cords is a routine sash window repair procedure that can often be completed by a competent do-it-yourself handyman.  Sash Window Specialist published the first ever internet diy guide, explaining how to replace sash cords in the 1990’s.

Sash Cords

Traditional sash cords are made from waxed cotton rope that will perish over time due to general wear and exposure to ultra-violet light.  UV from sunlight weakens the natural fibres in traditional sash cords and ultimately they will all snap.  

The ‘everlasting’ sash cords that we fit as standard are far more durable and UV stable.   Waxed sash cord is still available on request. 

Sash Chains

Far less common than sash cords.  Sash chains work in the same manner but utilise a bicycle type chain in-place of rope.

Whilst we can replace just the sash cords or chains in your sliding sash windows the best value for money repair service that we can offer you is our Draught Sealing & Sash Window Overhaul Service.  Draught seal & overhaul not only replaces the sash cords but also upgrades the energy efficiency with concealed draught seals and ensures the window is preserved and restored to face many more years of trouble free use.

Sash Window Spring Balance

Sash Window Spiral Balance.There are a variety of spring balances that have been incorporated into sliding sash windows since the 1950’s. 

Replacement balances are manufactured in a range of lengths and weight ranges to suit the glazed window sash.  Sash Window Specialist can replace broken spring balances to repair sash windows that incorporate all types of spring balances.

These can be a little more tricky to fit than sash cords and often diy handymen or carpenters fail to get them right. 

Repair Rotten Windows

Casement window repair with new sill. Sydney NSW
Repair rotten window sill on a casement window

Repair Rotten Window Sill

Sash window repair in Kilburn, North West London.
Box Sash Window Repair

The most common area of rot development is the window sill, fortunately we are expert at replacing rotten sills. We utilise a range of products during our sill repair projects. The traditional methods of splicing in a new hardwood sill are greatly improved by bonding the repaired sections using modern solutions such as epoxy resins & polyurethane glues.  We select all of our materials to ensure we provide a durable, permanent repair that will last for many years to come.

See more examples of our sill repair work

Repair Window Sash

Epoxy resin used to repair window sash.
Epoxy being used to repair sash joint.

Unlike with aluminium or uPVC windows a wide range of repairs are possible with traditional wooden windows.

Timber Bay Windows

Timber bay windows protrude from the building line which makes them more exposed to the elements.  Being more exposed, along with the additional joints in the window frames, often means that bay windows rot more quickly than other period window types.  To replace these windows is always an expensive project because they comprise at least three individual windows joined together.   Bay windows also support a structure above them that must be supported during replacement. 

Rebuild & Repair Bay Windows

Sash Window Specialist have economically rebuilt many rotten bay window frames with either casement or double-hung sashes.  First we must remove all rotten wood, which generally includes removing all of the existing window sills and a significant part of the vertical timbers.  A replacement hardwood window sill can then be fitted and splice repairs performed to rebuild the lower vertical sections.  Bespoke replacement sash frames or casements are then installed into the repaired bay window frames.  Our bespoke sashes and casements are supplied paint finished with low-e double glazing or single glazed for conservation areas.  All of our window renovations are draught sealed as standard.

How We Repair A Victorian Bay Sash Window

Repair Period Doors, Door Frames and Side Lights.

Heritage Shop front with door | Sash Window Specialist East
Shop front restoration.

Sash Window Specialist do not only repair wooden windows we also repair period doors including front doors, patio doors and french doors.  The same skills required to repair wooden windows are employed to repair rotten doors and door frames.  We also ease and adjust the door to ensure it is not binding and that the door locks properly align.

See more examples of our door refurbishment & repair work.

Modern Repair Materials

Using Epoxy to Repair Wooden Windows

Timber Window Repair & Upgrade | Sash Window Specialist NSW
Rotten casement window repaired using epoxy resin.

Using epoxy resin to repair rotten wood has a proven track record from the shipwrights who have use it extensively to repair wooden boats.   We use the same marine grade epoxy resins to repair rotten windows & doors.  Epoxy can be cut and shaped to match damaged mouldings or used to bond open sash joints.  Whilst it is an expensive product it does offer a superior wood repair that will last decades, unlike the cheap polyester based 2 part fillers or ‘builders bog’ that does not bond nearly so well.  Used alone or combined with a timber splice or dutchman (embedded timber block) the epoxy bonds extremely well to the original wood ensuring a long lasting permanent fix.

See more examples of our epoxy resin repair work

Epoxy resins provide an advanced solution to rectify timber defects and repair rotten windows or doors.

 Repair Heritage Windows & Doors 3   Repair Heritage Windows & Doors 4  Repair Heritage Windows & Doors 5  

Repair Glazing


Replacing glass in an arched window - Manchester sash window specialist
Arched window replacement glazing.

Replace Broken Glass

We undertake glass repair and glazing upgrade work as part of our renovation services.  From simple squares to curved glazing we replace all types of broken glass in period homes.  We can supply all glass types including coloured, etched and patterned. 

For single glazed properties in conservation areas we can often supply reclaimed hand made glass to ensure that modern float glass does not spoil the heritage appearance of the property. Subject to availability.


Putty Pointing 

Putty glazing traditional sash windows

Linseed putty is the traditional compound used on heritage glazing.  When paintwork has been neglected the putty can dry out and crack allowing rain to soak into the wood, creating prime conditions for wet rot to develop.  We can replace failed putty but it then needs 7-21 days to form a skin before paint can be applied.  Due to this curing time the responsibility to over paint the putty is usually by others.  The paint should extend beyond the edge of the putty and onto the glass by 1-2 mm.

See more examples of our glazing work

Window Hardware

brass casement window hardware

It is seldom possible or economically viable to repair broken catches, pulleys or other window hardware.  We can however replace most types of architectural ironmongery on doors, casement windows and sash windows.

Is it ‘window cill’ or ‘window sill’?

Whilst both spellings are correct “window sill” is now the most commonly used form.  Architects and tradesmen still frequently use “window cill” as that spelling was commonly taught at technical colleges.  Our website originally used ‘cill’ but all references have since been changed to ‘sill’ to reflect the most common form, however some of our branches may still reference ‘cill’ in their quotes and invoices.

What is the difference between a scarf joint and a splice joint?

Both splice joints and scarf joints are traditional methods used to join timber members end to end in woodworking.  We use marine grade epoxy resins to glue and bond the joints, ensuring a long lasting repair.

Timber joints to repair wooden window frames

Bespoke Replacement Windows & Doors

If your windows have rotten beyond sensible economic repair then we can copy the originals and manufacture our ‘Authentic Replica’ bespoke timber sash windows & doors.  Our replica replacement windows are of the highest quality and constructed using traditional joinery construction methods.  We offer joinery crafted from premium timbers including Accoya Wood that has a 50 year warranty.