Timber Windows Heritage Windows – Box Sash
Go green with our environmentally friendly timber windows and wooden doors.

Heritage Windows - Box Sash

Our Heritage Sash windows are true heritage windows, the real deal. Featuring slim glass, real putty outside, separate glass between Georgian bars, slim mid rails and a small 135mm depth of frame, it is the perfect design to match the originals made many decades ago.

Read much more at the bottom of this page.

Heritage Windows - Box Sash Windows with
(14mm Krypton filled glass)

  • slimline 14mm Double glazing unit, filled with Krypton Gas, with approx 5mm heritage spacer bar edge lines, sprig fixing under putty to fix the glass, approx 7 to 8 mm glazing rebate
  • externally glazed with true putty sealing outside, and painted over for further sealing, to match originals windows made a 100 years ago
  • slim Georgian bars at 18 or 20mm with separate glass units
  • slim 30mm mid rails
  • a thin box sash frame at 135mm inside to outside thickness
  • our standard is engineered European redwood or hardwood Sapele.
  • whole timber elements can be used if preferred
  • standard is brush painted, or sprayed if preferred
  • concealed gasket system to prevent rattles and leaks
  • deep bottom rails
  • CE Marked EN 14351-1 2006+A1:2010
  • u-value = 1.5 W/m2K (measured on redwood items)
  • square end traditional pulleys and weights
  • fitch fasteners
  • d-handles
  • lifting Hooks
  • child Locks/ Extra Security available
  • arched or swept heads or arched frames
  • custom horn designs

Heritage Box Sash Windows Gallery

Heritage Box Sash Windows - A Window Into the Past

Heritage Windows, also known as Heritage Box Sash Windows, are a window into the past. These traditional style windows bring a unique character and charm to any home. With their beautiful designs, these windows offer a classic look that is sure to make your property stand out from the crowd. As well as looking great, our Heritage Box Sash Windows are highly energy and sound proof efficient. Thanks to the use of krypton gas filled slim glass units which look like original single glazing, but are much more efficient.

The history of box sash windows

The use of wooden windows dates back to the 16th century, when glass panes were first added to window frames. These windows became known as box sash windows, due to the weight-bearing box frame and sliding lower sashes. Since then, box sash windows have remained a popular choice in homes across Europe, with many countries adopting their own traditional designs.
Heritage Box Sash windows are an especially popular type of sash window, designed to replicate the look and feel of traditional wooden windows while providing modern levels of insulation and soundproofing. The popularity of Heritage Box Sash windows has only increased in recent years, with homeowners seeking to add style and character to their homes whilst also enjoying the benefits of modern insulation technology.

The features of heritage box sash windows

Heritage box sash windows are the perfect choice for those looking to add a touch of charm and character to their home. Authentic Timber Windows Ltd produces these windows with exceptional attention to detail, ensuring that they look exactly like the original windows.
They can be double glazed with very slim glass units, providing much more energy and soundproof efficiency compared to single glazing. Putty is used to match the window’s frame, creating an authentic look. The paint brush finish and slim profiles help the windows blend in perfectly with the home’s existing architecture.
The frames are made with timber, adding strength and durability for long-lasting results. Heritage box sash windows can be opened by only using the traditional cord and weight system.
For those wanting to add a unique feature to their home while maintaining an authentic look, heritage box sash windows are a perfect choice.

The benefits of heritage box sash windows

Not only do they look like genuine single glazed units, but they also feature double glazing that is both energy and sound-proof efficient. This means that you can enjoy the classic appearance of heritage windows while also benefiting from more secure and energy efficient features.

Installing heritage box sash windows is a great way to preserve the character and charm of your home, as well as enhance its value.


These windows have been designed and used many times for real conservation areas and councils that genuinely want to maintain English Heritage and prestige. Featuring all genuine design aspects to satisfy all Conservation areas and officers, our heritage box sash windows are a great way to ensure your home looks its best and meets the required standards. Ours is not a cheap imitation like many available and marketed as “Heritage Windows”!


Overall, investing in heritage box sash windows is a great way to benefit from both classic style and modern advancements. From increased energy efficiency to improved security, these windows offer a range of benefits that make them a great choice for any home. Heritage Sash Windows from Authentic Timber Windows Ltd offer the best of both worlds; their traditional design and solid timber frames look like genuine single glazed windows, but they have been specially designed to fit double glazing. This double glazing is very slim, energy and soundproof efficient, making it a great choice for those who want to maintain their home’s aesthetic without compromising on the genuine features of this window. Additionally, the windows are also filled with a krypton gas that further enhances their energy efficiency.


Investing in Heritage Windows from Authentic Timber Windows Ltd is a great way to maintain your home’s traditional charm while also benefiting from modern energy efficiency and security features. 

As always, we are here to help and advise our customers to make sure every project is a success – so please do Contact us for help.

Scroll to Top