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A Buyer’s Guide to Wooden Sash Windows

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Sash Windows Kids bedroom

Whether you are building a new home in the style of the Georgian era, renovating a Victorian property or replacing windows in a Grade I listed castle, wooden sash windows are likely to be a necessity to match the period and charm of the building.

Often associated with 18th and 19th century properties, wooden sash windows are thought of as difficult to operate, quite often having been painted shut over the years. They are seen as draughty, noisy, poorly insulated and lacking in security features; with modern wooden sash windows, this no longer needs to be a concern.

What are sash windows?

Timber sash windows are sometimes referred to as sliding sash windows, hung sash windows, or box sash windows. They are a specific type and style of window that uses the traditional ‘sash’ sliding design, as opposed to other window styles such as a casement window. There are many different designs and types of sash windows, some being single hung (one moving panel) and some being double-hung (two moving panels, both top, and bottom). You can also get triple or quadruple hung sash windows, but these are not used as often.

Essentially, they are wooden windows that feature at least two vertical sliding panels.

Sliding sash popular styles

Sliding sash windows are also easily customisable and come with several style options to choose from. Here is a selection of popular bar patterns that you could choose from for sliding sash windows.

How do sash windows work?

Sash windows work by balancing the sash with a counterweight using steel, cast-iron, or lead weights. This is hung on a cord that is covered by a frame. More recently, sash windows use spiral balances (which are coiled tensioned springs in place of the cords that need little or no maintenance and will last for many years), which allow you to open the window. When closed, the top and bottom sash locks together to prevent them from sliding.

Are sash windows a good idea?

Are wooden sash windows suitable for your home? This is a commonly asked question due to timber sash windows being used predominantly in period buildings. Wooden sash windows can be installed in all properties and are suitable for any home. With attention to detail and proper installation, wooden sash windows are not only suitable but look great in both traditional and modern properties. 

How much do wooden sash windows cost?

There are several variables when looking at the cost of timber sash windows. The final cost will be dependent on the size of your home, the glazing options you choose, as well as the frame and finish that you go for. 

You also need to consider whether you’re going to use a company to install your windows, or whether you’re going to install them yourself. 

The cost will also vary depending on the company you use, but the cost of timber sash windows starts from around £750 at Bereco for supply and delivery only. Installation costs can vary so its always best to get a couple of prices and where possible ask your window company for a supply and installation package price

Do sash windows need a lot of maintenance?

The level of maintenance your sash windows will need will depend on environmental factors and the construction of the window itself. However, it is important to understand how to care for timber windows in order to ensure they are kept in good condition and hold up over time.

Check our guide on Maintaining Timber Windows where we’ve outlined exactly what you need to know when it comes to caring for our timber windows. 

Any type of timber window will need a certain level of maintenance, but this can mostly be done yourself and there is a range of products (cleaning kits, stains, paints, varnishes, etc.) that will keep the level of maintenance needed to a minimum. The type of products needed will depend on the finish applied to your windows.

There may be more complex repairs that are needed, in which you would benefit from using professional services, but your timber window supplier will be able to help with this. 

How do you install wooden sash windows?

If you are installing into a new build property or an extension or renovation that will be signed off by building control, then your builder / developer can carry out the installation in accordance with our Timber Window Installation Guidelines and building control will check and sign these off as part of the inspections prior to completion.

If you are replacing existing windows then we recommend that you hire a professional who knows the building regulations and requirements to carry this out for you, ideally they should be certified by FENSA or CERTASS.

What is the best wood for sash windows?

Here at Bereco, we believe there are two timber options for sash windows. We are extremely passionate about timber and we believe that we should use only the finest quality, sustainably sourced materials. As such, we only use FSC100% certified timber, the two options being:  

Redwood – Scandinavian Pine

This is a popular choice and features a smooth surface, and achieves excellent durability. This option is perfect for painted finishes.

Hardwood – Dark Red Meranti

Our hardwood comes with a full chain of custody, meaning it has been sourced responsibly from forests. Each stage of sourcing has been tracked to ensure maximum quality of delivery in the final product. This particular timber features a pitted effect surface and a natural red hue. This is perfect for stain finishes. 


Can sash windows be double glazed?

Absolutely! There are several glazing options for sash windows, depending on your requirements. The specification of the glass you choose can have a dramatic effect on the performance of windows and doors, home comfort and heating costs. 

Our windows and doors incorporate double glazed units utilising a Softcoat Low-E coating as standard which provides excellent insulation.

Types of sash window glazing

24mm Double Glazing

Our Contemporary and Traditional wooden sash windows have 24mm double glazed units as standard, proven to be the optimal thickness for thermal efficiency.

  • Contemporary | Traditional 
  • Argon-filled as standard offering a centre pane Ug value as low as 1.0 W/m²K and overall Uw values as low as 1.2 W/m²K 

35mm Triple Glazing 

For increased thermal efficiency, triple glazing offers excellent centre-pane U Values as low as 0.5W/m²K with an overall U value as low as 0.8W/m²K.

  • Contemporary | Traditional 
  • Argon-filled as standard, with Krypton filled units available offering centre pane Ug values as low as 0.5 W/m²K and overall Uw values of 0.8 W/m²K (Krypton). 

24mm & 35mm Acoustic Double Glazing

  • Contemporary | Traditional 
  • Reduce noise levels in the home without compromising on style. 24mm acoustic glazing with overall window ratings up to 38dB and 35mm up to 42dB. 

Single Glazing & Slimline Double Glazing

Our Heritage Sliding Sash Window can be supplied with the options of 14mm Slim-Line double glazed units that are fully Part L compliant with U values as low as 1.2W/m²K or 4mm Single Glazing when specified.

4mm Single Glazing

  • Heritage 
  • We offer 4mm single glazed units, perfect for homes under strict conservation requirements. 

14mm Slimline Double Glazing 

  • Heritage 
  • This unrivalled krypton filled glazing unit mimics the appearance of single glazing whilst offering improved thermal performance with 8mm warm edge spacers as standard and centre pane Ug values of 1.2 W/m²K and overall Uw value of 1.3 W/m²K. 

Solar Control Glazing

  • Specialist glass with low solar gain is available on request. 

Spacer Bars

  • Spacer bars can be seen around the perimeter of the glazing. The standard option is an aluminium spacer. Warm edge spacers available in white, black, brown and grey can reduce ug values to as low as 1.0 W/m²K which will significantly reduce home heating costs.

Keep out the cold

Draught Proofing

Draughts are now a thing of the past;  Bereco wooden sash windows are fully weather-sealed, even at the parting bead and meeting rails for complete protection from the elements. Our Cords & Weights Sash Windows also feature a pulley wheel draught-proof casing for the prevention of draughts through the weight pocket.

Weather Testing

As part of the BlueSky High-Performance Timber Window Scheme, our wooden sash windows are certified to BS6375 Part 1 achieving outstanding results for air tightness, water tightness and wind resistance.

View Our Timber Sash Windows

Types of timber window sash design


Our Contemporary Range features simple lines and shapes including internal pencil round mouldings. 

  • Pencil Round Bars 16mm, 25mm, 35mm | 60mm (Solid)
Bereco Contemporary Bar
Contemporary External Moulding
Bereco Contemporary Bar Drawing
Contemporary Internal Bead
Contemporary Bar Options


Our Traditional Range features internal ovolo beading and external putty line sash mouldings to enhance the character of your home

  • Ovolo Bars 16mm (Lambs Tongue), 25mm, 35mm (Ovolo) | 48mm (Solid)
Bereco Traditional Bar Detail
Traditional External Moulding
Bereco Traditional Bar Detail
Traditional Internal Beading
Bereco Bar Details Traditional Range
Traditional Bar Options


Our Heritage Range incorporates period aesthetics such as internal lambs tongue profile glazing beads and external putty line style to mirror distinctive features of original timber windows.

  • Lambs Tongue Bars 16mm, 25mm, 35mm | 48mm (Solid)
Bereco Traditional Bar Detail
Heritage External Moulding
Bereco Heritage Bar Details
Heritage Internal Beading
Bereco Heritage Bar Details
Heritage Bar Options

Keep the tradition or make it modern?

Now that you know the what, where, why, and how on all things timber sash windows, it’s time to think about the style of sash window you’ll want. Here’s an overview of the different elements you could choose from. 

Cords & Weights

Early sash windows made from timber utilised either chain or cotton cord and lead weights for the method of operation; both unsightly and prone to breakages. The Bereco wooden sash window overcomes this by incorporating a pulley and weights lifting system featuring a heavy-duty nylon cord and self-lubricating pulley wheels.

Inline Spiral Balance

Modernise your window by choosing the latest semi-concealed inline design with a pre-tensioned spring. This allows you to retain the features of an original sash window whilst benefiting from innovative operation.

Design it or match it?


Our sleek Contemporary profile is specifically designed for modern or new build homes, Traditional profiles complement the style of period style properties whilst Heritage profiles have been exclusively designed with slim frame sections and specialist glazing for architecturally sensitive projects, listed buildings and areas where conservation approval is required.

Bar designs

An extensive range of bar designs including the ever popular Georgian 6 over 6 pane design and regency marginal bar design can be coupled with bespoke frame designs. Curved heads, curved sashes and even curved on plan frames and glazing make your home as individual as you are.

Sash Horns

There have been many designs of sash horns over the years. They can be applied to the top (external) sash only, to both the top (external) and bottom (internal) sashes, or left off altogether. Conservation areas around the UK all have different designs and styles that they require, as such at Bereco we offer 7 different style of sash horn to suit any property.


Historically, sash windows had to be painted after installation and re-painted every couple of years, which eventually resulted in the window being painted shut and unable to open. Bereco Sash windows are supplied fully factory finished to eliminate this problem, with an extensive 10-year warranty on paint finish for peace of mind.

Introduce a splash of colour with our extensive range of paint and stain finishes. Pick any RAL, BS or NCS paint finish to create a truly individual design statement. You can also choose from our exclusive Heritage Range colour scheme, as well as Farrow & Ball, Fired Earth and Earthborn colour matching where a traditional finish is desired.

Timber sash windows security features

With any property, security is a concern. Bereco wooden sliding sash windows are designed to incorporate the latest high-security features. Sash windows are supplied with Angel Ventlock or key-operated Vent lock combined with high-performance fitch fasteners to keep windows secure.

If you’d like to learn more about your options for timber sash windows, book a design consultation today with the team at Bereco or head to our blog for more advice. 


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