Our wealth of experience working with period properties, means we understand the desire to preserve as much charm, history, and originality as possible. This is not only a priority for period homeowners, but it is often a requirement of the local planning officer too. Owning a period or listed property, or a home sited within a conservation area no longer means your household must prioritise style over substance – modern window design, insulation, and thermal efficiency allows you to benefit from both simultaneously.

Our sash window services include sash repairs, upgrades, and sash window replacements. Our sash window services boast:

  • Structural restorationTimber frame restoration and redecoration. Includes removing rotten wood, repairing wood, repairing loose putty, redecoration.
  • Functional restoration – Smooth window operation. Includes unblocking window operation, cord replacement, latches replacement, weight adjustments, window furniture replacement/renovation.
  • Controlled ventilation – Draught proofing. Includes installing draught-proof seals, installing new staff bead/parting bead.
  • Improve thermal efficiency – Double glazing retrofitting. Includes rebating window frame, installing ultra-thin double-glazing units, rebalancing weights.

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Sash window repair

Sash window repairs is the staple of our service, combined with draught proofing, and double glazing of original sash windows. Old or damaged windows can make your property damp, cold and uncomfortable, and they can also pose security and safety risks. Even the smallest repairs can make a significant difference to your day-to-day life at home.

If you have noticed any of the following, your sash windows may need repair:

  • Gaps, or ill-fitting sashes/panes of glass.
  • Damage to the glazing.
  • Draughts and cold spots.
  • Broken frames or rotting timber.
  • Damage to windowsills.
  • Windows that do not open or close properly.
  • Damage to locks and window furniture.

Some of the repairs we regularly conduct are:

  • Draught sealing.
  • Improving insulation.
  • Window overhaul – We replace parting and staff beads with new retaining beads and draught excluders.
  • Repairs to damaged or rotting timber and sills.
  • Rebalancing and adjusting sashes within their frames.
  • Replace broken sash cords to lower and upper sashes with new, modern cords which are now unbreakable.
  • Window security is vital – We can install new locks, catches, ironmongery, or toughened glazing.
  • Make good and repair perished putty and replaced broken glazing.
  • Double glaze existing sashes by removing existing glazing and rebate deeper to allow for a double-glazed unit. Alternatively, we can retrofit vacuum insulated glazing into existing sash frames.
  • Double glaze replacement sashes by manufacturing new double-glazed sashes to match your original windows.

Sash window replacement

Occasionally, over the course of many years, sash windows can be damaged beyond repair. In this scenario, it may be necessary (and more cost effective) to have them replaced completely. Sometimes, we can salvage and repair the original box frames and just replace the sashes, or if necessary we can make a completely new unit including a new box frame and sashes.
Signs that a window replacement may be in order are:

  • Excessive rotting timber or lots of damage the window frames.
  • Windows that are warped, misshapen or with sashes that no longer fit into the frames.
  • Noticeable draughts and cold spots within the room.
  • Broken glass.

Examples of our sash window repair and replacement work

Check out how we have tackled joinery for period properties, listed buildings and more.

Double glazing original sash windows

Old wooden sash or casement windows can prove challenging when double glazing existing sash windows for these main reasons:


Rebates (the gap where a glass pane fits into) in such windows are quite narrow. Standard double glazing will not fit into these narrow style rebates.


Making the rebate deeper is unlikely to be approved by the local planning department, particularly if the property is listed or residing in an area of conservation. In fact, any alteration to the original features within these properties is frowned upon by local planning officers as their aim is always to preserve rather than replace.


Frames need to be strong enough to carry the extra weight of double glazing. Originally, they were meant to only carry the weight of single glazing and installing double glazed panes into such frames will make them dangerous to operate.


Sash windows operate by a system of weights and pulleys and, therefore, the extra weight of double glazing may impact their smooth operation.

Luckily, we love a challenge at Parsons Joinery and are approved installers of Fineo vacuum insulated glass. Therefore, gaining planning permission for homes within conservation areas and period and listed properties is not a problem for us.

Fineo glass is only 6.7mm thick yet excels in the thermal performance of a standard size triple glazing unit. Plus, its super slim profile means it is easily retrofitted into the narrow rebates associated with period properties.

We boast a 100% success rate for planning applications submitted for conservation areas. Plus, all our planning applications for Fineo glass installations have also been approved to date.

Fineo vacuum-sealed double glazing has a market-leading 15-year guarantee, whereas most slim double-glazing systems only offer a 5-year guarantee due to their use of inert gases, which escape over time and lead to the loss of thermal efficiency. Fineo glass is vacuum-sealed, making it more thermally efficient and robust.

Fineo compared with traditional glazing

We can either retrofit Fineo into existing windows/sashes:

Or manufacture completely new sashes using Fineo glass.

For more information about our sash window repair or sash replacement services, contact the team today and we will chat through your options.