An Explanation Of Flush Casement Windows And Non-Flush Windows

An Explanation Of Flush Casement Windows And Non-Flush Windows

Unless you have some depth of window-related knowledge, you may be unaware of the difference between casement windows and flush casement windows.

They are two separate and very individual window products and it’s the ‘flush’ feature that differentiates these two window solutions.

A ‘flush’ casement window is called such because its window sashes sit flush with the window frame to create a perfectly flat surface.

In a standard ‘non-flush’ or ‘lipped’ (as it’s also known) casement window, the sashes marginally overlap from the frame.

View both from side-on in your local Hazlemere showroom and you will identify the distinction in their designs.

When did flush and non-flush casement windows originate?

Flush casements can be dated back to over 200 years ago and the 19th century, a period when timber was the solitary material utilised to construct all windows.

That’s why so many properties of the late Georgian, Edwardian, and Victorian eras have timber-framed flush windows.

Non-flush casements, Britain’s most popular window style, have existed for slightly longer, becoming prevalent in the UK in the 18th century. Originally built from iron by blacksmiths, until timber took over and was then superseded by UPVC and aluminium.

A set of casement windows

What has sparked the flush window revival?

It’s been spearheaded by companies like us as we know some homeowners want their property to stand out with a different look and flush windows provide an alternative aesthetic.

Our modern and authentic interpretation of a classic timber flush window retains its simple, clean lines and proportions but is made using an easy-care UPVC or aluminium profile to fulfil present-day thermal efficiency and security requirements.

A close-up of a flush casement window frame

Which of them will suit my home?

Flush UPVC windows are often accepted as a window replacement by planners for homes located in conservation areas and historic properties as they have the genuine styling to preserve the traditional look of older residences.

The flawless symmetry of flush sash windows can just as much suit modern buildings, notably when finished in a dark colour of Black or Anthracite Grey.

A lipped casement window has the all-round character to match almost every property type, old or new, which is why it’s such a prized window option.

An oak effect flush casement window

One of Hazlemere’s showroom advisors can give you a full product introduction and demonstration if you want to see our flush casements and standard casements up-close. Plan your journey here.


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Our showrooms are our shop windows and we have invested heavily to create extensive displays that best showcase our large range of windows, doors and living spaces. You will receive a warm welcome, plus a proper coffee, and the choice to browse at your leisure without interruption.


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