Double Glazed Casement Windows

Lasting performance & efficiency

About Double-Glazed Casement


Are you looking to buy durable, cost-efficient timber windows in the UK? Thinking of changing your sash windows for a more in-vogue double-glazed casement style?

Trade Timber Window Online is a leading supplier of timber windows, cheap windows, sash windows, and casement windows. Our casement windows feature the most up to date design twists that makes it easy to use with increased lifespan. Timber window frames are low-maintenance, durable, and a timeless choice for period and contemporary properties. Timber has closed the gap on uPVC with innovative manufacturing development, including new finishes and materials. Our double-glazed windows boast thermal efficiency and eco-friendly properties to provide natural insulation for your home.

You also have the option of painting them in any colour of your choosing. Our double-glazed windows are designed from glass architecture optimized to reduce heat loss, stay warm in winter, cool in summer, consume less energy, reduce condensation, prevent noise pollution, eliminate interior fading, and enhance resale value to ensure you never lose money when you buy authentic double-glazed windows from Trade Timber Window Online.



What is a double-glazed window?


Double glazing is a way to create an insulating gas layer either with special heavy gases or normal air between two panes of glass. It’s better at holding in heat while still letting in as much sunlight as single-glazed windows. Recently, double-glazing has become the standard in most UK homes and is worth considering as an option if your existing window isn’t properly insulated or requires extensive repairs or replacement.

The cavity is filled with either inert gas or dehydrated air to prevent unit condensation and improve insulation. Depending on the cavity width and type of window, each window unit is between 4 to 20 mm.

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Should I use a timber frame for my double-glazed window?

Timber frames are made from deciduous trees. They provide a unique, traditional look for your home while remaining energy-efficient, attractive, and durable. The most common options come from tropical mahoganies, butother options include beach, oak, and ash from European hardwoods. Timber frames can be varnished or stained depending on the wood variety. We always ensure the wood we sell to you is properly dried to avoid future shrinking or cracking. Except for historic buildings, our wood frames do not go above a U value of 2.0 W/m2K.

What are double-glazed casement windows?

There’s a reason why casement windows are very popular. They are timeless, versatile, and practical. Casement windows are windows with one or more hinges on which the sash swings for the window to open. The sash is the mobile part of the window. Compared to sash windows, casement windows are easily replaceable, great for efficiency, ventilation, customizable and reduce your carbon footprint in the environment.

Are casement windows worth the money?

When you’re looking for options to replace your tired windows, buying a pre-made casement window saves time, heartache, and money as they are designed to fit into pre-existing holes. If you already have a uPVC casement window and you’re looking to replace it with a timber option made from the latest building technology, it may cost a bit more but it’s worth it when you see the aesthetic beauty and value it adds to your home. Casement windows also provide great ventilation. If you decide on the double-hinged option, you can have a half-closed window or fully open window with unobstructed views, unlike Georgian windows.

What is in double-glazed glass?

The space between the double-glazing unit is filled with clear, odourless, non-toxic, low-thermal-conductivity gas, for insulation. It can be filled with:

Krypton: a costlier option that retains 66% more heat than air.

Argon: the cheap, more common option that retains 33% more heat than air.

Vacuum insulated glass: evacuated glazing units are hermetically sealed to eliminate heat loss.

Casement windows vs. sash windows

Casement and sash windows are the two most common types of window style. When it comes to choosing the best, appearance, insulation, environment, and climate all play key roles.

Casement windows have hinges that allow you to swing them open. They come in pairs that open away from each other and feature a crank that serves as a window lock. Sash windows were introduced in the Georgian era and remain a popular choice today. They have panels that slide atop each other to create openings. Casement windows are more energy efficient and feature a tight seal that compresses when you close the window. They offer a contemporary look that holds an aesthetic appeal, especially when fitted with timber frames. Casement windows are harder to break into because the lock is embedded into the frame. With larger glass panels, you have an unobstructed outside view, providing optimal lighting for your home interior.

Sash windows are more popular in Edwardian, Victorian, and Georgian homes. They are easier to open and simpler in design when compared to casement windows. They have fewer mobile parts which reduces the risk of malfunction and when it does spoil, a simple repair usually does the trick.

Why you should choose timber over uPVC or aluminium windows?

Many homeowners looking to replace double-glazing units usually consider three choices, uPVC, timber, or aluminium windows. Most will go with uPVC because it’s cheaper. However, if you want to increase the property value of your home, reduce energy bills and ensure maximum thermal efficiency, you should go with timber.

Timber-framed windows are beautiful to look at and offer a more decorative option than uPVC or aluminium. Depending on your property, you can go for a modern look, traditional or something in between. You can also choose from an extensive range of bar and colour finishes to highlight the finesse and style of your double-glazing window unit. If you care about the environment, you should know that wooden frames are more eco-friendly, with a negative GWP. This means that they reduce Co2 from the atmosphere over a long period of time, whereas uPVC increases your carbon footprint. Aluminium is a weak insulator. You’ll notice this phenomenon on a metal surface if you touch it with your bare hands on a cold day. On the other hand, wood is natural insulation that retains more heat than air in your home and lowers emissions of carbon.

What is the benefit of insulated glazing?

Energy efficiency: insulated windows reduce noise issues by preventing outside noise from entering your home. The architectural elements of insulated glazing prevent heat loss in the cold seasons and keeps air in during the warm season. Your home therefore remains cosy and warm all year round. The temperature increases to 56 degrees against 30 degrees for non-insulated windows.


insulated windows have several Low-E coatings that provide better protection against cold and heat. They perform especially well with wood, fibreglass, and vinyl material.

Sound insulation

double-glazed units are harder to break than single-pane windows, increasing home security. The reinforced sealing ensures they’re harder to break from the outside.

Protects home furnishing

the glass engineering and science of double-glazed units reduces the amount of sunlight and heat in your home. This prevents damage to valuable properties such as paintings, carpets/rugs, furniture and other items.

Reduced condensation

moisture that freezes into frost from the warm surface makes the home interior colder, forcing you to adjust the heating and increasing energy bills. Double-glazing glass technology prevents condensation by blocking moisture in cold weather.

What to look for when buying double-glazed windows


The right type of glass

the building materials used in double glazing is efficient and highly insulated. Double-glazed units are graded A, B, C with A being the best. You can get self-cleaning glass, laminated glass, or toughened safety glass, depending on your choice or advice from a surveyor.

Check energy ratings and accreditation

it’s essential you check the grading for a supplier’s window to know the thermal efficiency and acoustic insulation of your new window. The rating is determined by the British Fenestration Ratings Council. The installer you choose should be a member of FENSA or another professional body that awards accreditation. Check that they have experience installing wood double-glazing casement windows.


Timber double-glazing units are low maintenance. Most manufacturers offer a 10-year warranty. So, if there is an issue within that time frame, it will be repaired at no extra charge. Read the fine print to know what’s excluded in the warranty

Payment plans

most companies have a financial package with flexible payment options.

Other tips for buying double-glazed windows:

  • Do research on your product
  • Choose a reputable firm you can trust
  • Make sure the double-glazed window frames are glazed from the inside
  • Cheap doesn’t mean best

How much is a double-glazed window?

The cost of double glazing depends on the number of windows to be installed and on which floor. Windows above ground floor cost more due to scaffolding for setting up installation. The exact cost is determined after the installer checks your home. Other factors affecting cost include the size of the window, style of window and frame material to be used during installation. You’ll be provided with a rough estimate based on the details below.

Flat with 4 windows – from £2,140

House with 8 windows – from £4,500

House with 10 windows – from £5,350

House with 15 windows – from £8,450




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