Skip to main content
Excellent5 star Trustpilot ratingTrustpilot
Harrington Windows
double-glazed sash windows, timber sash windows, uPVC sliding sash windows, traditional sash windows, sash window double glazing, sash horns, georgian bars, conservation area windows, soundproof sash windows, energy-efficient sash windows.
Harrington Windows Logo
By Harrington Windows
Windows & Doors

Sash Window Double Glazing Guide

5 min read
Share

When it comes to upgrading windows in period properties or traditional homes, box sash windows offer aesthetic and functional advantages, making them the perfect solution to keep the traditional look while increasing energy efficiency and ease of maintenance.

Whether you’re looking to double glaze timber sash windows, uPVC sash windows, or replace old windows altogether, this guide will take you through the benefits, costs, and key considerations.

What are Sash Windows?

Definition and History

Sash windows are a classic window style that features two glazed panels, known as sashes, which slide vertically within a frame. These windows are often found in period properties and traditional homes, adding a touch of elegance and historical charm. Originating in the 17th century, sash windows were initially designed to improve ventilation and allow more natural light into homes.

Over the centuries, they have evolved to incorporate modern materials like uPVC and advanced technologies such as double glazing, enhancing their energy efficiency and overall performance. Whether crafted from timber or uPVC, sash windows remain a popular choice for homeowners looking to blend traditional aesthetics with contemporary benefits.

Why Double Glazed Sash Windows?

Double glazing involves two panes of glass separated by an insulation barrier to reduce heat transfer and improve thermal performance. The use of slim-profile double-glazing units for sash windows is perfect as it increases energy efficiency, reduces external noise, and adds modern functionality whilst keeping the classic look.

Benefits:

  • Energy Efficiency: Double-glazed units reduce heat loss so your home is warmer in winter and cooler in summer.
  • Noise Reduction: Two panes of glass provide sound insulation so your home is quieter.
  • Durability: Toughened or laminated glass increases lifespan.
  • Condensation Reduction: Double glazing reduces moisture build-up on window panes.
  • Preserves Period Features: Keep the charm of traditional sash windows with a modern twist.

See more aboutuPVC sash windowsto keep the classic looks with low maintenance benefits.

Double Glazed Sash Windows

Timber Sash Windows

Timber sash windows are perfect for listed buildings and conservation areas. They keep the authenticity of traditional wooden sash windows with modern double glazing for better thermal performance. These windows often have deep bottom rails and Georgian bars for the classic look.

Learn more abouttimber sash windowshere.

Sliding Sash Windows

uPVC sash windows are a cost-effective, low-maintenance solution for homeowners. These windows feature safety enhancements like travel restrictors to limit the window's opening and robust locking systems to ensure security and prevent unauthorised access. With multi-chambered frames, these windows have excellent insulation properties and a modern look. uPVC sliding sash windows are popular in modern builds looking for a traditional style.

Check out ourSliding Sash windowsfor more details.

Alu-Clad Sash Windows

Aluminium clad timber windowscombine the look of wood with the durability of aluminium. These composite windows have an aluminium exterior for weather resistance and a timber frame for warmth and charm.

Read aboutalu-clad timber windowsin our composite window guide.

Retrofitting Double Glazing to Existing Sash Windows

Can Existing Windows be Double-Glazed?

Absolutely, existing sash windows can be retrofitted with double glazing. This process involves replacing the original single-glazed sashes with new double-glazed units, significantly boosting the windows’ energy efficiency and performance.

Retrofitting is an excellent option for homeowners who wish to maintain the original character and charm of their sash windows while enjoying the modern benefits of reduced heat loss and lower energy bills.

By upgrading to double glazing, you can enhance the comfort of your home without compromising its historical integrity.

Double Glazing Sash Windows Cost

The cost of double glazing sash windows depends on the material, size, and style. On average:

  • uPVC sash windows: £400 - £600 per window
  • Timber sash windows: £900 - £1,200 per window
  • Aluminium-clad windows: £1,200 - £1,800 per window

Verticalsliding sash windowsoffer cost benefits due to their low maintenance and energy efficiency, making them a smart investment for homeowners.

Seecasement windowsfor alternative pricing.

Double Glazed Sash Window Material Comparison

Frequently Asked Questions about Sash Window Double Glazing

Can sash windows be double glazed?

Yes, sash windows can be double glazed. This involves installing new double-glazed units into existing frames or replacing the sashes entirely. It's advisable to consult with a specialist to ensure compatibility and maintain the window's integrity.

How much does it cost to double glaze a sash window?

The cost to double glaze a sash window ranges from £500 to £1,800 per window, depending on materials, size, and design. uPVC options are generally more affordable, while timber and aluminium-clad versions are more expensive.

How do you stop condensation on sash windows?

To reduce condensation:

  • Improve Ventilation: Use trickle vents or open windows to allow moist air to escape.
  • Use Dehumidifiers: These devices reduce indoor humidity levels.
  • Upgrade to Double Glazing: Double-glazed windows have warmer internal surfaces, reducing condensation.

Should you wipe condensation off windows?

Yes, wiping condensation off windows is recommended to prevent moisture damage and mould growth. Use a dry cloth or squeegee to remove excess moisture, and ensure the area is well-ventilated to aid drying.

How do you insulate sash windows for winter?

To insulate sash windows:

  • Install Draught Proofing: Seal gaps around the window frame.
  • Use Heavy Curtains or Thermal Blinds: These add insulation.
  • Apply Secondary Glazing: An additional pane installed internally improves insulation.
Harrington Windows Logo

Harrington Windows Team

Window Specialists

Our team of window specialists brings over 25 years of experience in the industry, providing expert advice on home improvement, energy efficiency, and architectural aesthetics.

Certified Window InstallersEnergy Efficiency Experts