Timber sliding sash windows have a timeless appeal and are ideal for period properties as well as traditional style or even contemporary new-build properties. Our timber sliding sash windows offer exceptional performance with our patented sash seal, so you get a window that not only looks great, but also performs to the highest standards. We offer two types of sliding sash window:
Our wooden box sliding sash windows utilise a traditional cord, weight and pulley system. These provide a completely authentic sash window, perfect for listed buildings and where you want to be true to the period of the property. Our timber box sliding sash windows can be found in Georgian, Victorian and Edwardian homes and commercial properties throughout the UK. There are lots of examples in our case study section.
Timber spiral balance sash windows use a concealed spring-loaded mechanism rather than the traditional cord weight and pulley system. Since they do not require a box, the frame of a spiral balance sash is slimmer and ideal for more modern homes. This also applies where the opening is relatively small, and the customer wants to maintain as much light as possible.
With a choice of window layouts – square bay, angled bay, bow, Bay Windows arch top, internal arch and arch fillet options, all of our timber sash window designs allow for high levels of customisation. They also feature a choice of sash horns, window bars and elegant hardware and come in an unlimited range of colours.
Tested to exposure category 2000 – the highest classification, making our timber sliding sash windows durable and weatherproofed
Accoya ® linings are available on our timber sash windows for added durability where needed
Environmentally friendly designs, materials and processes
Great performance as standard and extensive test data to guide specification for optional enhanced acoustic performance
Tested to PAS 24 and Secured by Design
Available in a range of widths and styles
Dual seal design and unique patented sash seal both provide excellent draught proofing
With our range of customisation options, we make it possible for you to achieve the exact look and feel you desire for your timber sliding sash windows, enabling you to meet your property style and desired outcome.
Performance and technical specifications are both available for our Timber Sash Windows.
Performance
| Thermal | As Standard | Best |
|---|---|---|
| U-Value | 1.4 | 0.9 |
| Energy Rating | B | A+ |
| g-Value | 71% | As Required |
| LT | 81% | As Required |
| Acoustic | ||
|---|---|---|
| Rw | 30dB | 42dB |
| Weather | ||
|---|---|---|
| Classification | 2000 (BS6375 Part 1) | |
| Air | Class 4 (EN 12207:2000) | |
| Wind | Class 7A (EN 12208:2000) | |
| Water | Class C5 (EN 12210:2000 Class C5) | |
| Operation & Strength | ||
|---|---|---|
| Classification | Pass (BS6375 Part 2) | |
| Security | ||
|---|---|---|
| PAS 24 / Part Q/ Secured by Design | Pass (as option) | |
| Sustainability | ||
|---|---|---|
| FSC Chain of Custody | Yes | |
CAD Drawings
NBS Data
Performance
| Thermal | As Standard | Best |
|---|---|---|
| U-Value | 1.6 | 1.2 |
| Energy Rating | B | A |
| g-Value | 71% | As Required |
| LT | 81% | As Required |
| Acoustic | ||
|---|---|---|
| Rw | 30dB | 42dB |
| Weather | ||
|---|---|---|
| Classification | 2000 (BS6375 Part 1) | |
| Air | Class 4 (EN 12207:2000) | |
| Wind | Class 7A (EN 12208:2000) | |
| Water | Class C5 (EN 12210:2000 Class C5) | |
| Operation & Strength | ||
|---|---|---|
| Classification | Pass (BS6375 Part 2) | |
| Security | ||
|---|---|---|
| PAS 24 / Part Q | No (high security spec available) | |
| Sustainability | ||
|---|---|---|
| FSC Chain of Custody | Yes | |
Learn more about how our timber sash windows have transformed properties
CASE STUDY
CASE STUDY
CASE STUDY
CASE STUDY
Find out more about the range of timber windows and doors we manufacture.
Our expertise in timber sash windows dates all the way back to our founding year in 1884.
We’ve been crafting high-quality timber sliding sash windows from our UK-based site ever since, sourcing durable and sustainable timber to ensure fine craftsmanship
Find out more about our background as timber window and door specialists here
We are proud to hold the Made in Britain certification, a mark of quality that shows our timber sash sliding windows are carefully designed, manufactured, and assembled right here in the UK.
We source our own timber for our products, priding ourselves on being one of the leading timber sash window suppliers in the UK.
We achieve this by using top-quality timber to ensure all of our products have a long life span and are low-maintenance for our customers.
Want to know more? You can read all about our Made in Britain certification and what it means for our products here.
At George Barnsdale, we specialise in crafting timber sash sliding windows that fit your home perfectly. As experienced timber window suppliers, we’ll guide you through every step, from the initial consultation and design right through to expert installation.
Whether you’re after replacement timber sash sliding windows or completely custom frames, our team has the skills and craftsmanship to deliver exactly what you need.
If you’d like to find out more about our bespoke timber sash sliding windows, get in touch today, and we’ll get back to you as soon as we can.
Both our box and spiral balance timber sliding sash windows can be single, double or even triple-glazed. For customers living in conservation areas or in listed properties who want to have the best thermal performance, we can offer vacuum glazing, which can perform as well as triple glazing but is as thin as a single piece of glass. Alternatively, we offer narrow double-glazed units for period properties. If you choose our historic range, glass can be fitted using a modern-day, high-performance putty alternative, which makes them ideal for listed properties if required.
Timber sliding sash windows can cost more than casement windows, but you can keep the cost down by choosing spiral balance sash windows; however, the investment is always worth it. Timber sash windows are highly sought after, and ours will last at least twice as long as uPVC alternatives.
We also offer the Tilting Spiral Balance design, which enables the window to tilt inwards to allow cleaning from the inside. These are great for those hard-to-reach windows.
If our traditional timber sliding sash window (vertical sliding sash window) does not meet your needs, we also offer the Yorkshire Sash, (horizontal sash window). Whichever option you go for, our attention to detail is second to none.
View our designs and contact us to discuss your ideas further.
At George Barnsdale, we prioritise your safety and security while maintaining the timelessness of our sliding sash bay windows. Each window is designed with advanced security features, including multipoint locking systems, reinforced timber frames, and quality hardware.
These elements work together to provide resistance against forced entry, giving you peace of mind. Our windows also are crafted to meet modern security standards without compromising their traditional charm.
Getting a quote for timber sash bay windows with George Barnsdale is simple and hassle-free. Our dedicated team is here to guide you every step of the way. Whether you prefer to reach out by phone, email, or through our online contact form, we’re ready to discuss your project in detail.
Share your specific requirements, including design preferences, dimensions, and any additional features you’re looking for, and our experts will provide tailored advice to help you make the best decision. Once we understand your needs, we’ll prepare a transparent quote that outlines the options available to you.
Yes, timber sliding sash bay windows can be installed in listed and heritage properties, and they are an excellent choice for maintaining the traditional character of such buildings. We understand the importance of adhering to strict conservation requirements while ensuring the aesthetic of historic properties is preserved.
Our timber sliding sash bay windows are designed to replicate the authentic details of period architecture, such as slim sightlines, traditional joints, and period-accurate glazing bars.
Founded in 1884, George Barnsdale is a family run business manufacturing high-performance timber windows and doors in Donington, Lincolnshire and offering a nationwide project management and installation service.
© 2026 George Barnsdale | High Street Donington, Spalding, Lincolnshire PE11 4TA | Phone: 01775 823000
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