Professional
Repair or Replacement of
Double Glazed Sash Windows

Keep your home energy efficient and aesthetically pleasing with our expert repair and replacement services for double glazed sash windows.
Our process begins with a thorough inspection to assess any damage or issues. For repairs, we address common problems such as broken glass, failed seals, and malfunctioning mechanisms, ensuring smooth operation and improved thermal efficiency.

If a replacement is necessary, we provide a seamless transition by carefully removing the old window, preparing the frame, and installing a new, custom-fit sash window that matches your home’s style, or a new style of your choice.

Our skilled technicians handle every step with precision, from fitting and adjusting the new window to applying the final touches that enhance durability and appearance. Trust our experienced team to deliver high-quality solutions that extend the life of your windows and enhance the comfort of your home.

Expert Double Glazed Sash Window Services in Kent and London
Upgrade Your Property While Preserving its Unique Heritage

Double Glazed Sash Window Repairs

If your double glazed sash windows have issues such as condensation between the panes, damaged frames, or faulty mechanisms, our skilled craftsmen can repair them, ensuring they regain their insulating properties and visual appeal. Common problems we fix include:

  1. Misted or failed double glazing – We can replace individual glazed units without the need for a full window replacement.

  2. Rotting or damaged timber frames – Our expert joiners repair or replace decayed sections while maintaining the integrity of the original design.

  3. Faulty sash cords, balances, or pulleys – We restore smooth and effortless window operation.

  4. Draughts and leaks – We provide draught proofing solutions to prevent heat loss and improve energy efficiency.

  5. Broken or loose glazing bars – Ensuring the traditional character of your windows remains intact.

  6. Free Aftercare Visit: Your satisfaction is our priority, which is why we offer a complimentary aftercare visit within 12 months of the installation. We’ll check that everything is functioning perfectly and address any issues that may have arisen completely free of charge.

A finished door
Wooden door from the outside

Double Glazed Sash Window Replacement

If your existing double glazed sash windows are beyond repair, we offer custom-built replacements that match the original style of your property while integrating the latest advancements in glazing technology.

Our replacement windows feature:

  • High performance double glazing for superior insulation and reduced energy bills.

  • Bespoke timber frames crafted from premium materials such as Accoya wood, ensuring longevity and durability.

  • Traditional aesthetics with modern efficiency, maintaining your home’s period charm while improving its thermal performance.

  • Customisable glazing options, including low-emissivity glass, acoustic glass, and toughened safety glass.

  • Heritage-approved designs, meeting conservation area requirements while upgrading your home’s comfort and security.

We carefully match your existing windows' style and proportions to ensure that any new installation seamlessly blends with the character of your home.

Materials That We Use

At Traditional Sash Windows and Carpentry, we use only premium materials to ensure durability, insulation, and aesthetic appeal. Our materials include:

  • HardwoodA stable and strong option for maintaining a traditional look.

  • Accoya woodA sustainable, highly durable timber that resists rot and provides exceptional longevity.

  • High-performance double glazing – We use low-emissivity (Low-E) glass for enhanced thermal efficiency.

  • Weather-resistant finishesOur timber is treated with high-quality microporous paints and stains to ensure long-lasting protection.

  • Heritage ironmongery Traditional fittings such as brass, nickel, and wrought iron hardware maintain the authentic look of period properties.

A finished repair job
A finished repair job

The History of Double Glazed Sash Windows

Double glazing as a concept dates back to the 19th century, but it wasn’t widely adopted until the mid-20th century, when energy efficiency became a greater concern. Traditional single-glazed sash windows, common in period properties, often led to heat loss and draughts.

The introduction of double glazing into sash window designs allowed homeowners to retain the aesthetic charm of their original windows while benefiting from improved insulation and noise reduction.

Today, advancements in timber treatments, glazing technology, and draught proofing ensure that double glazed sash windows provide exceptional energy efficiency without compromising on historical authenticity.

Interesting Facts About Double Glazing

  • Did you know? Early forms of double glazing were used in Scotland in the 19th century to combat harsh winters.

  • Heritage properties can still benefit – Many listed buildings now allow double glazed sash windows if they match the original aesthetic.

  • Energy savings – High-quality double glazing can reduce heat loss by up to 50%, significantly lowering energy bills.

  • Acoustic benefits – Secondary glazing or acoustic glass options provide excellent noise reduction, making them ideal for homes in busy areas.

  • Custom glass options – From frosted and decorative glazing to UV-protective coatings, modern double glazing offers various bespoke enhancements.

A finished repair job
A finished repair job

Why Choose Us for Double Glazed Sash Window Repairs & Replacements?

  • Expert craftsmanship – With years of experience in traditional joinery, we provide the highest level of quality.

  • Energy efficiency improvements – Our repairs and replacements help reduce heat loss, lower energy bills, and improve comfort.

  • Heritage-sensitive approach – We respect the architectural integrity of period properties while integrating modern performance enhancements.

  • Custom-built solutions – Each repair or replacement is tailored to your home’s specific needs.

  • Sustainable materials – We use eco-friendly timber and energy-efficient glazing solutions.

    A Final Note

    Investing in double glazed sash window repairs or replacements is one of the best ways to enhance the comfort, efficiency, and value of your home. Whether you want to preserve the character of a period property or improve insulation and security, our expert team at Traditional Sash Windows and Carpentry ensures that every project is completed to the highest standard.

    With our dedication to quality craftsmanship and sustainable solutions, we help homeowners enjoy the timeless beauty of sash windows while benefiting from modern advancements.

    If you're considering a repair or replacement, don’t hesitate to get in touch today for a free consultation and expert advice.

    Last updated 2025-07-21

    FAQ

    Can traditional sash windows be double glazed?

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    Yes. Traditional timber sash windows can often be upgraded with double-glazed units while retaining their original style and proportions. Depending on the condition and depth of the existing sashes, we may be able to reglaze them or manufacture new replacement sashes designed specifically for double glazing.

    Can you install double glazing into my existing sash windows?

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    In some cases, yes. This depends on the condition, thickness and design of the existing sashes. Older or particularly slim sashes may not have enough timber to safely accommodate double-glazed units. Following an inspection, we can advise whether reglazing is suitable or whether replacement sashes would provide a better long-term result.

    Will double glazing change the appearance of my sash windows?

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    We take care to preserve the traditional appearance of the windows wherever possible. New sashes can be manufactured to replicate the original glazing bar layout, mouldings, horns and other period details. Slimmer double-glazed units may also be available where maintaining narrow sightlines is important.

    What are the benefits of double-glazed sash windows?

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    Double glazing can help reduce heat loss, improve comfort, reduce outside noise and minimise cold draughts around the glass. When combined with professional draught proofing, it can significantly improve the overall performance of traditional sash windows.

    Does double glazing stop condensation?

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    Double glazing can reduce condensation on the inside surface of the glass because the internal pane normally remains warmer than single glazing. However, condensation can also be caused by high humidity, limited ventilation or cold areas elsewhere in the room, so double glazing may not eliminate it completely.

    Will double glazing reduce traffic noise?

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    Double glazing can help reduce outside noise, although the level of improvement depends on the glass specification, the gap between the panes and the condition of the window. Acoustic laminated glass, secondary glazing and effective draught proofing may provide better results where noise reduction is the main priority.

    Can you double glaze listed or conservation area windows?

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    Alterations to listed buildings usually require listed building consent, and properties in conservation areas may also be subject to planning restrictions. We can manufacture windows and sashes that closely replicate the existing design, but the property owner should confirm any consent requirements with the local planning authority before work begins.

    What type of glass do you use?

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    The glass specification will depend on the size, design and location of the window. Options may include standard energy-efficient double glazing, toughened safety glass, laminated glass, acoustic glass, patterned glass and vacuum glazing. We will recommend a suitable specification as part of the quotation.

    What is slimline double glazing?

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    Slimline double glazing uses a narrower overall unit than standard modern double glazing. It is designed for traditional windows where glazing rebates and sightlines are more restricted. Availability and suitability depend on the window design, required performance and manufacturer’s limitations.

    What is vacuum glazing?

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    Vacuum glazing uses two panes of glass separated by an extremely narrow vacuum space. It can provide strong thermal performance while remaining much thinner than conventional double glazing. This makes it particularly useful for traditional sash windows where preserving slim glazing details is important.

    Can you replace failed or misted double-glazed units?

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    Yes. If the sealed unit has failed and moisture has entered between the panes, we can normally replace the glass without replacing the complete window. We will also inspect the surrounding putty, glazing beads and timber for any additional repairs that may be required.

    Do you also repair the timber around the glass?

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    Yes. Where required, we can repair rotten or damaged timber using specialist resin systems, timber splicing or replacement components. If the sash is beyond economical repair, we can manufacture a new replacement sash to match the original window.

    Can double glazing be combined with a sash window overhaul?

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    Yes. Double glazing can be combined with an overhaul and draught-proofing service. This may include easing and adjusting the sashes, replacing sash cords or spiral balances, servicing the pulleys and weights, installing draught-proofing seals and fitting suitable new ironmongery.

    Will the existing sash weights need to be changed?

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    Yes. Double-glazed sashes are usually heavier than single-glazed sashes, so the sash weights or spiral balances may need to be adjusted or replaced. We calculate the correct balancing system to ensure the windows remain safe and easy to operate.

    Do you offer complete replacement double-glazed sash windows?

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    Yes. Double-glazed sashes are usually heavier than single-glazed sashes, so the sash weights or spiral balances may need to be adjusted or replaced. We calculate the correct balancing system to ensure the windows remain safe and easy to operate.Yes. We manufacture complete replacement timber sash windows and box frames using durable hardwoods and modified timbers such as Accoya. New windows can be made to replicate existing period details while incorporating modern double glazing, draught proofing and security hardware.

    Will the existing sash weights need to be changed?

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    Yes. Double-glazed sashes are usually heavier than single-glazed sashes, so the sash weights or spiral balances may need to be adjusted or replaced. We calculate the correct balancing system to ensure the windows remain safe and easy to operate.

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