
Box Sash Windows
Harnessing timeless designs and superior craftsmanship, we at the Traditional Window Company specialise in the creation of bespoke box sash windows, an embodiment of the UK’s rich architectural history. Every traditional sash window we construct is meticulously tailored to align with the original design, preserving the distinct period character of your home.
Our precision in crafting the original sash windows ensures a perfect fit within the original openings, delivering a seamless and classic finish. These unique box sash window details and our commitment to quality have made us a preferred choice for architects, discerning homeowners, and professionals working with Conservation Areas and Listed Buildings.
We’re not just a window company; we’re artisans dedicated to the restoration and preservation of the UK’s architectural heritage through our exceptional sash windows and box sash windows.
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Beautiful, Traditional Handmade Sash Windows
Key features of our sash windows
- The latest double glazed sealed units draught/weather seals
- Modified timbers with a 50 year guarantee not to rot or warp
- Advanced micro-porous paint covers with 10 year warranty
- Internally beaded glazing to maximise security and weather seal
All points help to maximise thermal insulation, durability and safety/security.

Testimonial
Timber
Stable timbers that enhance paint coating lifespan is the key to the long life of a window because if the coating remains intact, the window will last indefinitely.
Accoya® | A modified timber and one of the world’s leading, long-life woods with a 50 year warranty against rot and warping. |
Laminated Timber | Vacuum/pressure, Protim water based treated Redwood with a 30year warranty against rot and warping |
Natural Finish | Light oaks, Douglas Fir and Red Grandis with a 30 year warranty |
Glass
Glass & Glazing Types | Glazed to ‘A’ rated specification mainly consisting of 20mm Optiwhite glazing double glazed sealed units (4-12-4). This provides a centre pane U-value of 1.2w/m2k (the lower the number, the better the thermal insulation); The use of OptiwhiteTM glass helps to provide high visual clarity and purity of colour as there is no green tinge associated with some double glazing. This glass also gives more solar heat gain since it allows more heat from the sun, which can save on energy bills during the winter months. |
Other Glazing |
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Draught/Weatherproofing | To enhance the thermal insulation of the window, high specification seals, concealed within the window structure, are positioned so that they can be easily replaced if and when necessary. |
Finishes
Finishes | The latest, most advanced micro-porous treatments and finishes are used to maximise longevity and minimise future maintenance.
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Ironmongery |
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Safety & Security | Security, lockablesash fasteners and 2 (No.) sash stop locks fitted to each window, including child safety/ventilation locks as standard. |
FAQ’s
What is special about the Box Sash Windows from the Traditional Window Company?
Our Box Sash Windows are individually handcrafted following the period detail, profiles, and proportions of the original. They are designed to match the original design and retain the period character of your home whilst maximising thermal insulation.
What are the key features of your Box Sash Windows?
Our Box Sash Windows feature the latest double-glazed sealed units, draught/weather seals, and modified timbers with a 50-year guarantee against rot or warping. They also have advanced micro-porous paint covers with a 10-year warranty and internally beaded glazing to enhance security and weather seal, and heat insulation.
What type of timber is used for your Box Sash Windows?
We use a variety of high-quality timbers for our Box Sash Windows, such as Accoya®, Sapele, laminated timber, and natural finish woods like light oaks, Douglas Fir, and Red Grandis. All our timbers come with warranties against rot and warping.
What kind of glass and glazing do you use in your Box Sash Windows?
We use ‘A’ rated 20mm Optiwhite double glazed sealed units for the majority of our windows, but we also offer a variety of other glazing options such as toughened glass for safety, laminated glass for security, acoustic glass to reduce sound transmission, and more including heritage/historic glass. We can customize the glazing to meet your specific needs.
How are your Box Sash Windows installed?
Our experienced team handles the installation process with care, ensuring minimum disruption. We remove and dispose of the old windows, and then install the new ones, finishing them off with internal stub sills, architrave, and period trim to match the original design. The immediate walls surrounding the window are made good/decorated applicable to complete the look.
What finishes do you offer for your Box Sash Windows?
We use advanced micro-porous treatments and finishes for our Box Sash Windows to maximise longevity and minimise maintenance. We can colour match specified paint colours, provide a dual colour option, and offer natural wood finishes.
How do you ensure the security of your Box Sash Windows?
Our Box Sash Windows are fitted with security, lockable sash fasteners and two sash stop locks per window, including child safety/ventilation locks as standard.
Can you install Box Sash Windows in conservation areas and listed buildings?
Yes, we are experienced in working with planning requirements for conservation areas and listed buildings. We have undertaken many successful planning applications and appeals to The Planning Inspectorate.
What kind of ironmongery is used in your Box Sash Windows?
Our Box Sash Windows are fitted with high-quality ironmongery available in brass, chrome shiny or matt finish. They feature high-quality pulleys with pre-stretched sash cords and lead weights for smooth, effortless operation.
Conservation Areas & Listed Buildings
We are conversant with the requirements for planning and have undertaken many successful Planning applications and where required, successful appeals to The Planning Inspectorate.
Fensa Building Regulation Certificate of Compliance
Where applicable for windows and doors we will arrange certification following installation.
Our Accreditations
