Vacuum-Glazed Timber Sash Window Replacement, Edinburgh

Upgrading Traditional Timber Sash Windows with Vacuum Glazing in Edinburgh

For the owners of this period property in Edinburgh, improving the thermal performance of their windows was an important part of upgrading their home. However, maintaining a consistent, traditional appearance across the property’s front elevation was equally important.

With a combination of existing timber sash windows and more recent uPVC replacements, the property required a considered approach to window upgrades.

Ventrolla was appointed to manufacture and install three complete new timber sash and case windows to replace the existing uPVC units, alongside seven pairs of bespoke replacement sashes fitted into retained and refurbished timber box frames.

All ten window openings incorporated slim-profile vacuum glazing, combining the appearance of traditional sash windows with modern thermal performance.

Replacing uPVC Windows with Traditional Timber Sashes

A key element of the project involved removing three existing uPVC windows from the first-floor front elevation and replacing them with complete timber sash and case windows.

Located within a three-part bedroom bay, the new windows were manufactured to match the profiles and proportions of the property’s other traditional sash windows.

Each window incorporated a one-over-one sash configuration, with new timber box frames, cords and weights, and vacuum glazing.

The replacement windows were finished in white internally and externally, with brass catches, sash lifts and sash eyes completing the traditional detailing.

By replacing the uPVC units with bespoke timber sash windows, Ventrolla was able to establish a more consistent appearance across the front elevation while introducing the benefits of modern vacuum glazing.

Bespoke Vacuum-Glazed Sashes Within Existing Timber Frames

Elsewhere in the Edinburgh property, the existing timber sash box frames were suitable for retention, allowing Ventrolla to replace the moving sashes without removing the complete window assemblies.

Seven pairs of new vacuum-glazed sashes were manufactured and installed. Each replacement pair incorporated vacuum glazing in a traditional one-over-one configuration, designed to match the profiles of the existing sashes.

The retained timber box frames received a full refurbishment, with new sash cords and weights installed to support the operation of the replacement sashes.

This approach allowed the original window structures to remain in place wherever practical, while introducing new glazing and timber sashes to improve performance.

The Benefits of Vacuum Glazing for Traditional Sash Windows

One of the most significant features of this Edinburgh project was the use of vacuum glazing across all ten window openings.

Unlike conventional double glazing, vacuum glazing uses a vacuum between two panes of glass to provide effective thermal insulation within a particularly slim unit.

This makes it an attractive option for traditional timber sash windows, where glazing thickness, frame proportions and architectural detailing can influence the choice of glazing.

Ventrolla’s vacuum glazing offers a centre-pane U-value of approximately 0.7 W/m²K, compared with approximately 5.82 W/m²K for traditional single glazing and 1.2–1.4 W/m²K for Ventrolla’s slim heritage double glazing. A lower U-value indicates reduced heat transfer through the glazing, helping to improve thermal insulation.

Despite its slim profile, Ventrolla vacuum glazing also allows approximately 80% light transmission, compared with 88% for single glazing and 78% for slim heritage double glazing.

Vacuum glazing can also offer solar heat gain values as low as 0.2, depending on the specification, helping to manage the amount of solar energy entering a property.

For this project, the use of 8.38mm LandVac units enabled the homeowners to incorporate advanced glazing technology into traditional one-over-one timber sash windows.

The result was a consistent glazing specification across both the complete replacement windows and the new sashes installed within existing frames.

Vacuum glazing is becoming an increasingly popular option for upgrading traditional timber sash windows, particularly where retaining slim glazing profiles and original architectural detailing is important.

This approach has also been used on other Ventrolla projects, including a listed Georgian property in Bristol, where bespoke Sapele hardwood sashes were manufactured to accommodate vacuum glazing while retaining the existing timber box frames.

Repairing and Preserving Existing Timber Window Frames

Alongside the installation of new vacuum-glazed sashes, Ventrolla carried out targeted timber repairs to several of the retained window frames.

The music room window required a replacement timber sill due to decay along its front edge, together with repairs to the pulley stiles.

Further sill replacements and pulley stile repairs were specified for the three-part lounge bay and both spare bedroom windows, addressing areas of deterioration while retaining the surrounding timber frames.

Where existing frames remained in good condition, such as the right-hand music room window, they were refurbished without unnecessary timber replacement.

This selective approach allowed Ventrolla to address damaged components while preserving the original joinery wherever possible.

Draught-Proofing, Maintenance and Window Operation

In addition to the vacuum glazing, each window incorporated Ventrolla’s Perimeter Sealing System (VPSS), designed to reduce draughts around the moving sashes and improve everyday comfort.

The windows were also fitted with Ventrolla’s Sash Removal System (SRS), making it easier to remove the sashes for future maintenance and decoration.

A Simplex easy-clean system (only available in Scotland) was incorporated into the first-floor windows, providing improved access for cleaning.

The ground-floor lounge and spare bedroom windows also included locking brass catches and security stops, combining traditional ironmongery with practical security features.

Together, these systems were designed to improve the operation, maintenance and everyday performance of the property’s timber sash windows.

A Consistent Approach to Traditional Window Upgrades

The project brought together two complementary approaches to upgrading traditional windows at this Edinburgh property.

Where modern uPVC units had replaced the original windows, complete new timber sash and case windows were manufactured to restore a more appropriate appearance.

Where existing timber box frames could be retained, bespoke vacuum-glazed replacement sashes were installed alongside refurbishment and targeted repairs.

Across all ten window openings, the consistent use of LandVac vacuum glazing provided a modern glazing upgrade while maintaining the familiar proportions and operation of traditional timber sash windows.

The project demonstrates how vacuum glazing, bespoke timber joinery and careful assessment of existing frames can be combined to improve the performance of period properties without unnecessarily replacing sound original timberwork.

Specialist Vacuum Glazing and Timber Sash Window Replacement in Edinburgh

Ventrolla specialises in the restoration, renovation and bespoke replacement of traditional timber sash and casement windows throughout Edinburgh, Scotland and the wider UK.

From replacing unsuitable modern windows with traditional timber designs to incorporating vacuum glazing into bespoke replacement sashes, our approach focuses on preserving architectural character while improving comfort, performance and longevity.

For more information about our vacuum glazing and heritage window services, visit ventrolla.co.uk or contact our team on 0800 0277 454.