What Is the Difference Between Box Sash Windows and Sliding Sash Windows?

As they look the same, you might think it’s quite hard to spot the difference between box and sliding sash windows – the clues in the box!

B ox sash windows always have the traditional mechanism of ropes and pulleys with iron or lead weights. This allows the sash panels to move up and down. They are sometimes also referred to as a ‘hung sash’ or ‘sash and case’. Sliding sash windows without the box are usually operated by a modern spring-loaded device, and these are often the design of choice for more contemporary homes.

What’s the history behind the box?

The box was devised for aesthetic reasons, to conceal the mechanism for moving the window and give the whole appearance a grander, more seamless look. But there is a bit more to it than that.

A Building Act in London in 1709 stated that sash windows had to be recessed 4” back from the outer brickwork or masonry. Exposed sash boxes were seen as a fire risk. The Fire of London in 1666 left a real legacy.

There was another Building Act in 1774 during the height of Georgian architecture, which stated that the sash window box frame had to be set behind the brickwork so that only about an inch of the sash box was visible from the outside.

However, it seems the Acts were not always followed, and whether there was any penalty for not obeying the construction rules seems to have vanished in the mists of time.

Architectural Clues

The cord, weight and pulley mechanism altered over the decades and can be used to help date a sash window. By the 1750s, sash pulleys were set into iron frames with a solid brass face plate. The grooves in which the lower sash moved were often not painted, as this did often cause the sashes to stick or completely jam affecting their smooth operation.

Designs changed with cast iron and brass sash pulleys superseding the earlier types, demonstrating that sash window design really did evolve, so the focus shouldn’t just be on the glazing and number of panes, the usual hallmark used to date a window style.

Choosing a Sash Window Style for your Property

It’s vital to choose a sash window that suits your property. That might be obvious because you have an old property and want to follow what’s been there for decades, but what happens if you have a newer home, or you want to keep your old windows and make modifications to them? There are so many sliding sash window styles, designs and features you could opt for that it can become quite overwhelming. Here’s a list of considerations to help you make the right choice.

  • Do you want to refurbish your windows to upgrade their efficiency, or are you looking for complete window replacement?
  • Is window replacement prompted by a functional purpose or better design aesthetics?
  • Could your sash windows work better? Where are the snags?
  • Framing material should serve you for all climatic conditions as well as keep the physical and stylistic aspects of the window. Timber has a natural and rich look as well as being architecturally authentic for older properties and period homes. Timber is sturdy, resilient and durable and, with the right fit and glazing, is an excellent insulator.
  • Aim for a window which is durable and easy to operate with minimal maintenance requirements.
  • Consider draughtproofing, sound control, thermal regulation and security.
  • Have the windows been altered, so they are no longer authentic for the age of the property? Can the original design be reinstated? Is it practical?

Regardless of the sash window style you decide on, always choose the best quality as this will pay you back many times over, both in terms of what the windows look like, how they perform and the ROI – Return on Investment. Replacing or upgrading windows is one of the leading home improvements in terms of increasing the value of your property, so it represents a very worthwhile investment.

All our box and sliding sash windows are made from quality hardwood. We can bespoke a new design to suit your home or faithfully replicate the original windows. Our repair and restoration service allows you to choose modifications and refurbishments which won’t alter the appearance of your sash windows but upgrades thermal regulation, soundproofing, security and draughtproofing using the latest modern materials and techniques. We offer a huge choice of styles, shapes and sizes for period and contemporary homes and work both on-site and at our own workshops. We pride ourselves on providing a blend of traditional craftsmanship with innovation and design.

Contact us to find out more about our sash window repair and restoration services.