Construction of Timber Sash Windows

A quick intro to sash windows

Sash windows or ‘box sash windows’ as they’re most commonly known, are boxy in name and in nature. The frame is essentially a box that houses the sashes.

These sashes freely slide up and down and are counterbalanced using a pulley system. Meanwhile, the weights that enable this to happen are hidden within the frame.

How sash windows work

The tops sash hangs on the outer side of the window and the bottom sash hangs on the inner side of the window. An equal weight balances the weight of the sash, and when done right, you can lift the sash effortlessly or;

The sash window slides up and down, which is the key differentiator. This type of window isn’t common in the rest of the world and is typically only found in British colonial countries.

The history of sash windows

This is a sketch of a sash window from an old joinery and carpentry book that was published in 1902.

Joiners who built all the period properties around London back then learned from books like these.

But a lot has changed since 1902!

Many joineries and larger window companies have compromised along the way, and now make timber sash windows that are completely different to traditional sash windows. But they’re still calling them sash windows!

There are 3 key features we’ve kept that other window joinery companies haven’t (more on what they are below).

Timber sash windows now

Feature #1: Back in the day, original sash windows were made with a 140mm thick frame. We still work to this thickness.

But many other joineries make their frames much bigger. And this means the frame actually juts out into rooms. What’s more, thicker frames don’t sit flush with the wall and therefore don’t look as nice as thinner frames.

Feature #2: Traditional sashes were also thick. So we make sure our sashes are the same thickness!

Thicker sashes look much nicer and are far more elegant. It’s a feature that forms part of our standard window work in most conservation areas. Meanwhile, other sash window companies charge a premium for conservation windows because it’s not classed as standard work.

Feature #3: Traditional frames incorporate the sash weights. We build our frames in exactly the same way.

The pulley system is mechanical and doesn’t break. This means sash window owners should have no problem with opening and closing their windows, even after decades of use. Other companies now use spring balance systems, which don’t work as well and stop working after 5 or 6 years.

6 more facts about our sash windows

As well as staying true to the original design and manufacture of timber sash windows, we:

1. Use a double draught seal in our sashes

Why? Other companies use just 1 seal, but we use 2 because it doesn’t just help keep draughts out, but sound too!

2. Use sash cords with a nylon centre that have been wrapped in woven cotton and waxed

Why? The wax helps the sashes operate seamlessly. They feel nicer and smoother to use, and the nylon makes sure the sashes don’t end up snapping.

3. Use double glazed windows

Why? To keep the heat in your home, save money on heating bills whilst also reducing outside noise and increasing security.

4. Use new and improved timber

Why? Using new and improved timber makes the windows last longer because you don’t want to constantly spend your valuable time and money maintaining windows.

5. Use new ironmongery and locks

Why? Not only does ironmongery look beautiful and help achieve the perfect finish, it can be customised to match our customers’ other hardware. We use high security locks that are made to the highest standard to help prevent break-ins.

6. Fully spray finish our windows

Why? From a practical perspective, windows need to be spray painted in a factory or workshop because the conditions need to be controlled, plus it’s an incredibly dirty and dusty job! But the end result is stunning – a wonderful satin finish that looks beautiful and really makes the windows stand out.

And that is why we offer the best double glazed sash windows in London