Timbawood specialises in bespoke box sash windows that perfectly complement the architectural charm of period, conservation and listed properties. In this article, we’ll look at the key features and ranges of our box sash windows, from our Heritage range approved for listed buildings to our Conservation range ideal for Edwardian, Georgian and Victorian properties. Find out how these sash windows can enhance the beauty, security and energy efficiency of your home while maintaining its historical integrity.
What is a box sash window?
A box sash window is a traditional type of window commonly found in period properties. It consists of one or more movable panels, or “sashes”, that glide vertically to open and close. These windows are set within a box frame that houses the counterweights, typically using cords and pulleys, allowing the sashes to move smoothly and stay in place at any position.
Typical features of a box sash window include movable sashes mounted in frames that slide up and down, a box frame containing the mechanism for balancing the sashes, usually with weights and pulleys, hidden counterweights within the box frame that help to balance the sashes for easy opening and closing, slim glazing bars that divide the glass panes and fine mouldings.
What is the difference between a box sash window and spring balanced sash window?
The main difference between a box sash window and spring balanced sash windows is how they work. Though they look similar, their mechanisms are different. A box sash window uses a traditional system of cords, weights, and pulleys inside a vertical window box to balance the sashes, making them easy to open and close. This box is often hidden behind brick or stone or placed near the brickwork with a decorative trim.
Modern sliding sash windows, however, sometimes use springs instead of weights and pulleys. Spring balanced sash windows feature a spiral-shaped rod within the frame which connects to a spring that can be adjusted to the weight of the sash. These modern mechanisms are slimmer than box sash windows but less traditional.
How have box sash windows evolved over time?
Box sash windows have changed a lot over time, especially in how they operate. They originally used a system of cords, weights, and pulleys hidden in the frame to lift the sashes smoothly. This timeless design, which makes the sashes very easy to move, is still popular today, although spring sash windows have also emerged in recent times as a slimmer, cheaper option.
The glazing system in modern box sash windows has also improved. Slim panel double glazing reduces sight lines and preserves the period look better than standard chunkier double glazing. These improvements help box sash windows keep their classic appearance while offering better functionality and insulation. This makes them a popular choice for both historic and modern properties.
At Timbawood, we specialise in exact-match, handmade box sash windows that preserve the character of listed, conservation and period properties while upgrading the security and insulation performance, with features such as slimline double glazing, high security hardware and the most durable, energy efficient timber.
Depending on the specification and level of preservation required, our timber box sash windows are available in four ranges:
Heritage Range Box Sash Windows
Our Heritage Range box sash windows have been approved for listed buildings throughout London and the South East. More than just a range, our exact-match, bespoke windows are ideal for listed buildings and more stringent conservation areas, with exact-match mouldings, section sizes and glazing bars.
Whether it’s single glazing or slimline double-glazing, hand puttied and hand painted, no requirement is impossible. We offer box frame depths from 120mm that can meet Part L building regulations for thermal efficiency, featuring individually glazed units as slim as 12mm (4-4-4).
Conservation Range Box Sash Windows
Our made to measure Conservation Range box sash windows feature an array of options including our elegant slimline double glazing and slender section sizes, designed for conservation properties and period properties that require exact-match profiles, mouldings and glazing bars.
These box sash windows feature 16mm (4-8-4) krypton filled glazing units with applied glazing bars. Although these windows feature slightly thicker units than the Heritage Range, they are also an elegant solution for architecturally sensitive properties.
Period Range Box Sash Windows
Our Period Range box sash windows are ideal for Edwardian, Georgian and Victorian properties that aren’t listed or in a conservation area. We are able to match the existing design and offer a choice of mouldings including lambs tongue, bevel and ovolo.
These box sash windows feature 20mm (4-12-4) argon filled glazing units with applied glazing bars.
As with the Conservation and Heritage Ranges, the Period Range is made with Accoya timber due to its strength and durability. We offer a full range of glazing options and hardware finishes, as well as a colour-matching service, to ensure the windows are in keeping with the original look of the property.
Traditional Range Box Sash Windows
Our Traditional Range box sash windows, made with engineered redwood, are suitable for period and modern properties, as well as new-build homes.
These box sash windows have a frame depth of 168mm and feature 24mm (4-16-4) argon filled glazing units with applied glazing bars.
As with all our ranges, the Traditional Range box sash window is available with weights and pulleys or spring balances, and a variety of glazing, paint and hardware finishes. All our glazing units feature a Low E soft coat pane for improved insulation, and additional options include acoustic glass for improved sound insulation and laminated security glass. For more information on the specifications available, please get in touch to speak to one of our specialists.
