How to Repair and Maintain Sash Windows
Three experts reveal how to get sash windows running smoothly and looking beautiful
Julie Butterworth
21 November 2018
Houzz Contributor and homes, architecture and property journalist. I work on a range of homes websites and edit commercial and editorial digital content at the Royal Institute of British Architects Journal. I have managed subbing departments at magazines Country Homes & Interiors and Ideal Home and web content teams for Time Inc UK’s Homes Network.
Houzz Contributor and homes, architecture and property journalist. I work on a range... More
Sash windows are the beating heart of any period home. They come in a range of styles and configurations and when they go wrong, they demand an eye for detail and an expert hand. From upgrading cords to fitting new sections, here’s what to consider if you need to restore yours.
Identify your sash window design
The two main styles of sash are Georgian (pictured above) and Victorian (pictured below). Georgian windows have glazing bars and multiple panes of glass within the moving sashes. Victorian versions have one or two large panes in each moving sash. Later, Edwardian designs featured a mix of the two.
The two main styles of sash are Georgian (pictured above) and Victorian (pictured below). Georgian windows have glazing bars and multiple panes of glass within the moving sashes. Victorian versions have one or two large panes in each moving sash. Later, Edwardian designs featured a mix of the two.
Sash windows can be singular, or form part of a bay. Unlike casement windows (with hinges) and hopper (or tilting) windows, sashes have the advantage of remaining flush to the wall when open and do not impede blinds and shutters.
Styles can change with variations in window sills, sash horns, glazing and moulding profiles. These features can help you assess if your windows are likely to be original (or based on original designs) and will inform any decisions around possible repairs and refurbishment.
Browse more transitional living areas
Styles can change with variations in window sills, sash horns, glazing and moulding profiles. These features can help you assess if your windows are likely to be original (or based on original designs) and will inform any decisions around possible repairs and refurbishment.
Browse more transitional living areas
Understand how sashes work
Sash windows comprise an outer frame or box, and usually a pair of vertical sliders or ‘sashes’. However, they can be fixed so neither sash moves; or single hung, where only one of the sashes moves, usually the bottom one.
Traditional sash windows operate using a pulley and counterweight system. Cords are connected to weights that sit inside the frame and counterbalance the movement of the sashes, holding them in place when they’re pushed up or down.
Sash windows comprise an outer frame or box, and usually a pair of vertical sliders or ‘sashes’. However, they can be fixed so neither sash moves; or single hung, where only one of the sashes moves, usually the bottom one.
Traditional sash windows operate using a pulley and counterweight system. Cords are connected to weights that sit inside the frame and counterbalance the movement of the sashes, holding them in place when they’re pushed up or down.
Be aware of what can go wrong…
Sash cords can break over time, resulting in the weights being lost in the sash box. If there are gaps around the sashes, the windows can rattle, let in draughts and leak. Poor redecoration is also a factor and can cause windows to stick.
General neglect and inadequate maintenance can cause the wood to decay and rot, but thankfully timber is, for the most part, repairable.
Sash cords can break over time, resulting in the weights being lost in the sash box. If there are gaps around the sashes, the windows can rattle, let in draughts and leak. Poor redecoration is also a factor and can cause windows to stick.
General neglect and inadequate maintenance can cause the wood to decay and rot, but thankfully timber is, for the most part, repairable.
…and what’s involved in fixing it
Replacing the cords and weights inside the box frame is one of the more straightforward and least costly repairs associated with sash windows.
“More extensive repairs often require sectional replacement,” says Adrian Thompson, managing director at UK-based Refurb-a-Sash. “This can include renewing the lower sill, replacing sash frames or renovating the existing box frame.”
Replacing the cords and weights inside the box frame is one of the more straightforward and least costly repairs associated with sash windows.
“More extensive repairs often require sectional replacement,” says Adrian Thompson, managing director at UK-based Refurb-a-Sash. “This can include renewing the lower sill, replacing sash frames or renovating the existing box frame.”
“The timber windowsill gets the brunt of the weather, so can often require a lot of renovation work,” says Chris Herrington, technical manager at Ventrolla in the UK. “The rot seeps up the window from the sill, causing the decay – and sometimes a completely new sill and lower box assembly is needed.”
For any sectional replacement work like this, the window is taken apart, any rotten timbers are routed out to get back to the sound wood, and new timbers are spliced in. Once the work is done, the window is re-hung and balanced so it works smoothly.
For any sectional replacement work like this, the window is taken apart, any rotten timbers are routed out to get back to the sound wood, and new timbers are spliced in. Once the work is done, the window is re-hung and balanced so it works smoothly.
Find a tradesperson with heritage experience
“Period properties require exceptional attention to detail, as windows were not made to a standard specification,” says Richard Dollar, managing director at The Sash Window Workshop based in the UK. “Make sure the company you choose has experience of working on similar properties. Are they members of any accredited bodies?”
Windows are an important element of your home and can involve significant expense. “Ask your supplier for written referrals, visit their workshop and check their credentials,” says Thompson. “If the suppliers are based miles away, how will they service any guarantee work?”
Get three or four quotes for any work, Herrington advises, “but make sure you’re comparing like with like when assessing price differences.”
“Period properties require exceptional attention to detail, as windows were not made to a standard specification,” says Richard Dollar, managing director at The Sash Window Workshop based in the UK. “Make sure the company you choose has experience of working on similar properties. Are they members of any accredited bodies?”
Windows are an important element of your home and can involve significant expense. “Ask your supplier for written referrals, visit their workshop and check their credentials,” says Thompson. “If the suppliers are based miles away, how will they service any guarantee work?”
Get three or four quotes for any work, Herrington advises, “but make sure you’re comparing like with like when assessing price differences.”
Weigh up glazing options
It’s possible to install replacement double-glazed sashes into existing box frames using slim glazing panels. “Our workshops make these to match the profile of the existing sashes,” says Herrington, “and you can choose from a range of timbers and glass types, such as acoustic or thermal.”
Be aware that while fitting double-glazed sashes into an original box frame does not constitute the wholesale replacement of an original window, you may still need to seek permissions for the work, depending on where you live.
Windows of Opportunity: Your Guide to High-Performance Glazing
It’s possible to install replacement double-glazed sashes into existing box frames using slim glazing panels. “Our workshops make these to match the profile of the existing sashes,” says Herrington, “and you can choose from a range of timbers and glass types, such as acoustic or thermal.”
Be aware that while fitting double-glazed sashes into an original box frame does not constitute the wholesale replacement of an original window, you may still need to seek permissions for the work, depending on where you live.
Windows of Opportunity: Your Guide to High-Performance Glazing
Fit draught-proofing
Draught-proofing is important because of the way sash windows are designed. “Gaps around the sashes mean they can rattle and let in draughts, rain and dust,” says Herrington. “Installing a draught-proofing system in the gaps solves these problems.”
Another option is timber secondary glazing, says Dollar. “This involves fitting an additional glazed screen on the inside in front of a sash window. It can improve thermal efficiency and reduce noise, and is often a popular choice in [heritage] listed buildings.”
Shutters and window treatments can also contribute to energy efficiency, says Thompson. “Fully closed plantation shutters and interlined curtains can make a big difference in winter.”
Draught-proofing is important because of the way sash windows are designed. “Gaps around the sashes mean they can rattle and let in draughts, rain and dust,” says Herrington. “Installing a draught-proofing system in the gaps solves these problems.”
Another option is timber secondary glazing, says Dollar. “This involves fitting an additional glazed screen on the inside in front of a sash window. It can improve thermal efficiency and reduce noise, and is often a popular choice in [heritage] listed buildings.”
Shutters and window treatments can also contribute to energy efficiency, says Thompson. “Fully closed plantation shutters and interlined curtains can make a big difference in winter.”
Consider the costs
Costs will vary enormously depending on the condition and size of your windows and the complexity of the work and materials involved. For the straightforward replacement of all four cords in upper and lower sash frames, expect to pay upwards of approximately AU$220 per window (some companies have a minimum cost or charge a call-out fee as well).
Draught-proofing can cost upwards of around AU$600 per window, with larger windows fetching higher prices, and more complex renovations and upgrades often costing double this or more.
Costs will vary enormously depending on the condition and size of your windows and the complexity of the work and materials involved. For the straightforward replacement of all four cords in upper and lower sash frames, expect to pay upwards of approximately AU$220 per window (some companies have a minimum cost or charge a call-out fee as well).
Draught-proofing can cost upwards of around AU$600 per window, with larger windows fetching higher prices, and more complex renovations and upgrades often costing double this or more.
Decide if it’s better to repair or replace
As well as the cost, the condition of your windows will be a key factor in whether you choose to repair or replace a sash window.
“We like to think we can save a window that looks beyond repair,” says Herrington, “but it depends on customer preference and budget. Original timber is far better quality than the wood we get today, so with a little bit of care and attention, plus some ongoing maintenance, timber windows can last another 100 years.”
As well as the cost, the condition of your windows will be a key factor in whether you choose to repair or replace a sash window.
“We like to think we can save a window that looks beyond repair,” says Herrington, “but it depends on customer preference and budget. Original timber is far better quality than the wood we get today, so with a little bit of care and attention, plus some ongoing maintenance, timber windows can last another 100 years.”
If the frame is still in good condition, you may be able to just replace the moving parts, says Dollar. “One advantage of timber windows is that they can often be repaired if issues are dealt with promptly.”
“There’s no golden rule around repair versus replacement,” says Thompson. “The important thing is to ensure any work is faithful in style, appearance and operation to the original, and maintains the integrity of the building.”
“There’s no golden rule around repair versus replacement,” says Thompson. “The important thing is to ensure any work is faithful in style, appearance and operation to the original, and maintains the integrity of the building.”
Check your local council regulations
If your home is heritage listed or you live in a conservation area, speak to your local council’s heritage officer about any work you want to carry out on sash windows.
“In [heritage] listed buildings, it’s always preferable to renovate rather than replace,” says Herrington. “However, we are seeing more cases of slim double glazing being authorised for installation in listed homes.”
If your home is heritage listed or you live in a conservation area, speak to your local council’s heritage officer about any work you want to carry out on sash windows.
“In [heritage] listed buildings, it’s always preferable to renovate rather than replace,” says Herrington. “However, we are seeing more cases of slim double glazing being authorised for installation in listed homes.”
Draught-proofing or changing the sash cords and weights will not require planning permission, says Dollar, “but more major repair work, such as re-glazing or installing new sashes into existing frames, may.” If you’re unsure, speak to your local council.
“Consent should be sought for double glazing and renewal,” says Thompson, “but works in conservation areas should not be an issue, as long as homeowners stick with timber, and the windows end up with the same appearance and design as the originals.”
What to Consider When Renovating a House in a Heritage Overlay
“Consent should be sought for double glazing and renewal,” says Thompson, “but works in conservation areas should not be an issue, as long as homeowners stick with timber, and the windows end up with the same appearance and design as the originals.”
What to Consider When Renovating a House in a Heritage Overlay
Keep up with regular maintenance
Once any repair or restoration work is done, it’s important to check timber and paintwork frequently. “We recommend painting or varnishing external timber sills annually to make sure they’re weather-tight,” says Herrington.
Open sash windows often to prevent them from sticking, Dollar advises. “Check any handles, trickle vents and working parts every year and lubricate them with silicone spray or light oil,” he says. “The timber framework of windows should be cleaned thoroughly every year, too, including the working parts.”
Once any repair or restoration work is done, it’s important to check timber and paintwork frequently. “We recommend painting or varnishing external timber sills annually to make sure they’re weather-tight,” says Herrington.
Open sash windows often to prevent them from sticking, Dollar advises. “Check any handles, trickle vents and working parts every year and lubricate them with silicone spray or light oil,” he says. “The timber framework of windows should be cleaned thoroughly every year, too, including the working parts.”
For 10- to 12-year repainting cycles, Thompson recommends using modern microporous paint. “Then, other than cleaning traffic film off the paintwork and occasionally oiling the pulley and locks, sash windows will be relatively maintenance-free,” he says.
Tell us
Have you recently restored or upgraded your sash windows? Share your experiences in the Comments section below, save this story for future reference, and join the conversation.
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Find a window professional near you
Tell us
Have you recently restored or upgraded your sash windows? Share your experiences in the Comments section below, save this story for future reference, and join the conversation.
More
Find a window professional near you
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first job i ever had was making sash windows, still love them today ,and have recently made a floor to ceiling cedar sash window for the garden hut..looks wonderful
"10 to 12 year repainting cycles?" we should be so lucky! We used microporous paint with the right primer, undercoat etc on our sash windows. It's been absolutely no better than any more common-or-garden paints. Perhaps it's the Welsh weather, but the only one that has stood the test of time brilliantly is linseed oil paint. It's brilliant. Not that easy to use as it dries slowly and other idio-syncracies, but the performance and result are exceptionally good.
I had the original sash windows in my Edwardian house replaced in 2017. As the house is in a conservation area we had to have a carpenter make like for like, but were allowed to add double glazing. It looks like we are starting to get some rot (see picture) on the inside of the window (there isn’t much condensation) and I wonder whether this is a leak from the outside wooden beading that has been used around the glazing rather than putty. Is anyone able to diagnose and suggest how best to seal and resolve the problem before it progresses?