Casement windows blend style, security, and functionality seamlessly, making them popular among homeowners. 

The most frequently installed type of window, casement windows have side, top, or bottom set hinges and swing outwards, providing full ventilation. They are available in a wide range of designs, sizes, and colours and cost an average of £500, making casement windows one of the cheapest options when installing double glazing.

Our window experts explain everything you need to know about casement windows – from new windows’ cost to the best style for your home, making your decision easy.  

Casement windows: What are they?

Casements operate through a hinge mechanism attaching the window to the side, top, or bottom of the frame and can open outward to the left or right, or inward, depending on the design. 

They are operated by a small latch/fastener handle or crank handle located opposite the hinges, which also serves as the locking mechanism, ensuring the window remains securely shut or firmly held in position when open.

Casement windows’ ability to provide excellent ventilation, unobstructed views, enhanced security features, and energy efficiency contribute to their widespread appeal.

Most manufacturers produce several types of casement windows.

Single casement

Single casement windows consist of one large pane of glass hinged on one side, allowing them to swing open either inward or outward. They are simple, elegant, and versatile, fitting well into both traditional and contemporary architectural designs.

Double, or French, casement

Double casement windows, also known as French casement windows, have two sashes that open outward from the centre without a mullion in the middle, offering a full, unobstructed view. These windows are often chosen for their romantic, classical appearance and wide opening, facilitating ventilation and serving as an emergency exit route.

Push-out casement

Push-out casement windows are distinguished by their simple handles, allowing for manual opening. Unlike other casement types that rely on a crank mechanism, the push-out variant provides a more streamlined look that’s favoured in designs aiming for a minimalist finish.

Swing-in casement

Swing-in casement windows are designed to open inward, which can be particularly useful when exterior obstacles prevent a window from opening outward. This design also facilitates easier cleaning of the window from the inside.

With their diverse styles and mechanisms, casement windows offer something for every home, blending seamlessly with any architectural design while providing functionality, security, and energy efficiency. Their ability to adapt to different architectural styles and functional requirements makes them a popular choice in a wide range of residential settings.

Pros and cons of casement windows

Pros

Excellent ventilation: Casement windows can open fully, unlike some other window types, allowing for maximum airflow and ventilation into the space. Energy efficiency: When closed, casement windows seal tightly against their frame, reducing air leakage and improving energy efficiency. Unobstructed views: With fewer mullions and frames, casement windows offer clear, unobstructed views of the outdoors. Good security: Once a casement window is closed, there’s no way of opening it from the outside, increasing the security of your home.

Cons

Size limitations: Due to the mechanics of opening and supporting the window, casement windows are generally not suitable for openings larger than 170cm high. Exterior space: As they typically open outward, casement windows require clear space outside, which can be an issue in tight spaces or near pathways. Susceptible to weather: The outward-opening design of casement windows means they can be exposed to strong winds and rain, potentially allowing water into your home and increasing the risk of weather-related damage.
Flush vs stormproof casement windows

Flush and stormproof casement windows represent two distinct styles, each with a unique appearance and functionality, catering to different architectural needs and preferences.

 

Flush casement windows

This is an example of a timber flush casement window. (Adobe)

 

Flush casement windows sit flush within the frame when closed, creating a smooth, flat exterior appearance. This design offers a clean and simple aesthetic, often preferred for its elegant and understated look.

 

These windows typically open outwards and are known for their excellent ventilation and ease of use. The flush design, however, means they might not seal as tightly as stormproof casements, potentially making them slightly less efficient in terms of energy performance.

 

Flush casements are particularly popular for period properties, conservation areas, and listed buildings. Their traditional appearance and subtle design complement the architectural integrity of such properties, often making them the recommended choice to preserve their aesthetic and historical value.

 

Stormproof casement windows

Stormproof windows are much more common in uPVC frames. (Adobe)

 

Stormproof casement windows overlap the frame slightly when closed. This design offers an improved seal against the elements, making these windows particularly suitable for areas exposed to harsh weather conditions, such as strong winds and heavy rain.

 

While stormproof casements can be used in various buildings, their modern sealing and weather-resistant features make them a practical choice for new constructions or renovations where energy efficiency and protection against the elements are priorities. However, their look might not suit the strict aesthetic requirements of period properties or conservation areas where preserving historical accuracy is crucial.

How much does it cost to buy casement windows?

The cost of casement windows can vary widely based on several factors, including size, material, and glazing type. 

Generally, casement windows are considered to offer good value for their cost, especially when factoring in their energy efficiency, which can lead to long-term savings on heating and cooling expenses. 

Size

The size of the casement window significantly affects its price. Larger windows require more materials for both the frame and the glass, and the increased weight necessitates more robust hardware to operate the window smoothly. Therefore, as the window size increases, so does the cost. 

Material

The frame material is crucial in determining the cost of casement windows, with uPVC, aluminium and timber being the most common. 

uPVC is often the most cost-effective option, offering good insulation and low maintenance, while wood typically carries the highest price tag. Although admired for its thermal properties, aesthetic qualities, and longevity, wood windows require regular maintenance. 

Aluminium casement windows are known for their durability and slim frames, but they can be less energy-efficient unless equipped with a thermal break – a gap of at least one cm between the double glazing panes. 

Glazing type

The type of glazing also impacts the price of casement windows. Double glazing, consisting of two panes of glass with an air or gas fill in between, is most commonly seen in new windows. They provide better insulation, energy efficiency, and substantial savings over time compared with the single glazed units they might replace. 

Triple glazed windows, offering even better energy performance and noise reduction, are between 10 and 20% more expensive but can be justified in extremely cold climates or if your energy bills are particularly high.

Material Size Glazing type Average cost
uPVC 600mm x 900mm Double glazing £500
uPVC 600mm x 900mm Triple glazing £575
Aluminium 600mm x 900mm Double glazing £1,000
Aluminium 600mm x 900mm Triple glazing £1,200
Wood 600mm x 900mm Double glazing £1,500
Wood 600mm x 900mm Triple glazing £1,725

Maintenance of casement windows

Maintaining casement windows ensures their longevity, smooth operation, and energy efficiency. The routine maintenance required can vary depending on the material of the window frame.

  • uPVC: uPVC frames are very low maintenance, requiring only occasional cleaning with soapy water to keep them looking their best. Check the seals regularly to ensure they remain tight and efficient.
  • Aluminium: Aluminium frames are also low maintenance but should be cleaned periodically to maintain their finish. Check for signs of corrosion, particularly in coastal areas where salt air can be more abrasive.
  • Wood: Wooden windows require more upkeep due to their vulnerability to moisture and temperature changes. Regular painting or staining is necessary to prevent warping, rotting, or other water damage. Inspect for signs of wear and treat any discovered issues promptly to prevent deterioration.

For all materials, it’s crucial to lubricate the hinges and moving parts annually to ensure smooth operation and to inspect the hardware for any signs of wear or damage.

Common problems 

Casement windows can face several common issues, with repair costs varying based on the severity.

Difficulty opening or closing

If you’re experiencing difficulty opening or closing your windows, problems can often be resolved by adjusting or replacing the hinges or the crank mechanism. Costs for new hinges or a crank mechanism can range from £10 to £50, with labour adding to the price if a professional is required.

Faulty seals

Replacing or repairing failed double glazing seals can help eliminate draughts and condensation. Seal replacements might cost between £50 and £100, plus labour. However, in some cases, the window unit may need to be replaced entirely, costing an average price of £500.

Rot or corrosion

For wooden frames, repairs can cost anywhere from £100 for simple DIY tasks, such as sanding or repainting to over £1000 for extensive damage requiring professional restoration. 

Aluminium frames might need repainting or anodising, which could cost several hundred pounds depending on the extent of corrosion and the size of the window.

Hardware replacement

Replacing worn or broken handles, or locks can typically cost between £20 and £100 for the parts, with additional costs for labour if you’re not doing the work yourself.

Timely maintenance can prevent many of these issues from becoming serious, saving money in the long run. For significant repairs or replacements, it’s advisable to get multiple quotes from professionals to ensure competitive pricing.

Frequently asked questions about casement windows

Several alternatives to casement windows exist, each offering distinct advantages and characteristics suited to different preferences, architectural styles, and functional requirements:

  • Sash windows: Sash windows slide vertically up and down in the frame, with the ability to open from both the top and the bottom. They are particularly popular in period-style homes, offering excellent ventilation control and ease of cleaning, as many modern designs allow for the panels to tilt inward.
  • Horizontal ‘Yorkshire’ sash windows: Sliding windows have panels that slide horizontally, making them ideal for spaces where exterior opening is a concern, such as along patios or paths. They provide a contemporary look, require minimal effort to open, and are suitable for wide openings.
  • Tilt and turn windows: Tilt and turn windows can be opened fully like a casement window or tilted outwards from the bottom with the top of the window angled into the room. This is achieved via a double action locking mechanism.

Casement windows can leak for several reasons, often related to wear and tear or improper installation. Key factors include:

  • Worn seals: Over time, the weather stripping or seals around casement windows can deteriorate, allowing water to seep through gaps.
  • Improper installation: If a casement window is not correctly installed, it may not close fully or seal properly, leading to potential leaks.
  • Damaged or warped frames: Wooden frames can warp due to moisture or temperature changes, causing misalignment with the window sash. This misalignment can prevent the window from sealing correctly.
  • Faulty hardware: Broken or malfunctioning hardware may prevent the window from shutting tightly, creating spaces for water to enter.
  • Blocked drainage holes: uPVC windows are designed to enable water to flow off the surface and into the frame, and drain out through drainage holes. If these become blocked, water can back up and leak into the house.

Written by Katharine Allison Energy Saving Expert

Author

As a writer for FMB, Katharine researches and interrogates products and companies to find the best consumer purchases on the home improvement market – including heat pumps, home security systems and windows. Her high standards for up-to-date information and expert advice ensures that our readers can be assured that the products we recommend are top-rated and high-quality.

Katharine has worked with a wide variety of content publishers over her 12-year career as a writer, including Gordon Ramsay, Transport for Wales, Northern Rail, Cuvva Car Insurance, and a number of large construction firms and environmental organisations. Her work has been published in some of the UK’s leading publications, including The Independent and Architectural Digest. Katharine has also completed three degrees – fine art, philosophy and psychology – and is undertaking a fourth, in STEM, at the Open University. She co-founded the mental health charity Inner Allies and can often be found giving advice on their helplines at weekends.

On top of her impressive career and educational background, Katharine runs a racing team of sled dogs. She enjoys early morning dog walks along her local beach, watching the wildlife while looking forward to the first of many coffees.

Edited by Amy Reeves

Editor

Amy is our production editor, dedicated to fact-checking and prioritising accuracy and expertise. She is passionate about encouraging consumers and homeowners towards investing in their homes and creating a greener environment.

After graduating from The University of Leicester with a degree in English in 2016, Amy worked for Thompson Reuters before joining Future plc as Assistant Editor at Homebuilding & Renovating. During her five-years in this role, she interviewed hundreds of architects, industry experts, self-builders and home-improvers on topics ranging from renewable technology and home insulation to kitchen design and DIY advice. Her work has been published in Period Living, Real Homes, Homes and Gardens and 25 Beautiful Homes.

In her spare time, Amy can normally be found with a hammer or paint brush in her hand; she completed a whole-house renovation in 2022 and is about to embark on a eco-retrofit project to her cottage in Somerset.

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