Sash Windows

When we talk about sash windows, typically we are referring to a type of window that’s reminiscent of Georgian and Victorian architecture. These windows create a timeless appeal to a home, regardless of its age, enhancing its overall facade.

Traditionally, a sash window consists of two panels – known as sashes – that slide vertically within a frame to open and close. These classic designs are valued for maintaining that Georgian, Victorian, or Edwardian aesthetic.

Timber sash windows are well-known for their proportions, glazing bar patterns, and frame profiles, elevating the interior’s spaciousness and elegance. Getting these details right is what separates a well-designed wooden sash window from its mass-produced counterparts.

Types of Sash Windows

Box Sash Windows

Most timber box sash windows use a traditional weights-and-cords system, housed in a concealed box or case on each side of the frame. This is often considered the style most associated with period properties, achieving a quality hand-crafted finish.

Spring Balanced Sash Windows

Unlike traditional weights-and-cords, spring-balanced sash windows use a spiral balance concealed within the frame. These windows are more commonly used, and are considered a better choice for new builds or properties without a deep reveal to help maintain its unique charm.

Glazing and Performance

Double-glazed sash windows are the standard specification, using sealed units with low-emissivity glass and argon gas. Timber frames and sashes paired with high-specification sealed units also help achieve U-values that meet or exceed Part L of the Building Regulations.

If higher thermal or acoustic performance is needed, we offer vacuum glass as an alternative.

Why Timber

Our engineered timber allows for slender frame profiles and fine glazing bar detail that define the character of a period window. We achieve this quality by setting sash windows deep in the brickwork of the property, which is an integral part of our construction process.

Timber is a natural insulator, can be factory-painted in any RAL colour, and may be refinished over its lifetime. For sash windows, we use an Accoya and redwood timber combination for an optimal lifespan. Accoya forms the exterior of the frame and the window sill, and redwood forms the interior frame. The combination improves dimensional stability and reduces the risk of warping or shrinking over time.

When it comes to sash windows, using timber also meets the planning requirements of conservation areas and listed buildings, where traditional materials are often a condition of approval.

Costs

The cost of your ideal sash windows depends on the type, size, glazing specification, glazing bar pattern, timber species, and finish. The cost can also change depending on if the window is utilising a traditional weight and cords system or a spring balance one.

Please reach out to our team to get an accurate quotation for your property or project.

Frequently Asked Questions

What is a sash window?

A sash window has two panels (sashes) that slide vertically within a frame to open and close. The sashes are counterbalanced by either a weights-and-cords system (box sash) or a spring mechanism (spring sash). Sash windows have been a feature of British architecture since the late 1600s.

What are the different types of sash windows?

The two main types are box sash windows, which use a traditional weights-and-cords counterbalance system housed in a box frame, and spring-balanced sash windows, which use a concealed spiral spring mechanism for a slimmer frame profile.

How do sash windows work?

Both sashes slide vertically within the frame. In a box sash window, each sash is connected by cords to weights concealed in boxes on either side. In a spring sash window, a pre-tensioned spiral balance provides the counterweight. Either system allows the sashes to stay open at any height.

How much do timber sash windows cost?

The cost depends on window type, size, glazing specification, glazing bar pattern, timber species, and finish. Box sash windows typically cost more than spring sash windows due to the additional mechanism and materials.

Can sash windows be double-glazed?

Yes. Modern timber sash windows are routinely double-glazed with sealed argon-filled units and low-emissivity glass. Vacuum glass is also available where higher thermal or acoustic performance is needed.

Are timber sash windows suitable for conservation areas?

Timber sash windows are generally preferred and often required for conservation areas or listed buildings. Timber matches the original material of most period properties and can be detailed to replicate existing profiles and proportions.

What is the difference between a box sash and a spring sash window?

A box sash window uses a traditional weights-and-cords system concealed in a box frame on each side. A spring sash window uses a spiral spring mechanism within a slimmer frame. Box sash windows are typically specified for period renovations; spring sash windows suit new builds or properties without a deep wall reveal.

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