Different types of sash windows: what are the options?

An elegant, authentic timber sash window will give your home a classic period style. But what are the different types of sash windows, and what are the best options for your home?

Timber sash windows will bring a unique look to a property, with their period authenticity and traditional sight lines. They’re the ideal choice if you’re looking to renovate older homes in conservation areas and want the home to blend in with neighbouring properties, or you’re planning on sensitively upgrading a listed building. Here we explore the finer details of a sash window design and explore which options are right for your own property.

Sash windows are constructed from two movable sashes, one sitting in front of the other. Sash windows will have decorative sash horns, which is a common feature for this style. Sash horns are usually external, however, they can feature internally in Scottish windows. The windows will also include a concealed trickle vent, deep moulded lamb’s tongue profiles with 21 mm glazing bars, and internally moulded staff beads. Staff beads are the detailed trim that frames your sash box internally, keeping the sashes in place. Window cills can be timber, but they will often have a sub cill sitting on a stone cill.

Box or spring – what’s the difference?

Sash windows are either designed with classic lead weights and nylon chords for a truly traditional window, or a modern pre-tensioned spring balanced window which might be a better option for newer homes.

Box sash windows have the best of both worlds, combining traditional style with modern technology. They use pulleys, cords, and weights to counterbalance the top and bottom sashes. These weights are housed in a ‘box’, which is created by liners extending the frame on each side both internally and externally. These windows retain a classic heritage style while still benefiting from exceptional security, thermal and acoustic performance.

The spring balanced sash window is a modern day alternative to the classic box sash window. It’s often used in new-build properties where a flush reveal has been specified by the architect. It uses a spring-loaded mechanism rather than the traditional pulleys, cords, and weights.

Choosing the right glazing…

The optimal depth for a sash window is 68mm, which allows the window to incorporate a thicker and wider choice of energy efficient and sound reducing glass, including triple glazed panes. This means that you can benefit from that classic aesthetic while still enjoying all the benefits of a modern performing window.

Legacy sash windows…

If you are looking to match a draughty, original single glazed window with a modern replacement, then opt for legacy double glazed designs which are similar to a standard sash window, but with thinner frames, sash and glass sections. This will give a modern performance, without compromising on a traditional aesthetic.