Flush casement windows are a window type whose opening sash sits flush within the frame, forming a single flat plane across the face of the window when closed. Unlike a traditional “lipped” or stormproof casement, where the sash overlaps and protrudes slightly beyond the frame, a flush casement gives a clean, level finish that suits period and heritage properties. It is one of the oldest window styles in Britain and remains a favourite for homeowners who want an authentic, understated look.
If you are weighing up window styles for a period home, this guide covers what flush casements are, why they look the way they do, how they perform, and what to consider before you buy.
What makes a flush casement window different?
The defining feature is in the name. When you close a flush casement, the sash tucks neatly inside the frame so both surfaces line up flat. Run your hand across a closed flush casement and you feel one continuous plane.
A stormproof casement works differently. Its sash is rebated to sit over the frame, leaving a small raised edge. Stormproof designs became common in the twentieth century because the overlap adds a layer of weather protection. The trade-off is a chunkier, more modern profile that can look out of place on an older building.
Flush casements predate the stormproof style by centuries. Of all the casement window styles available today, the flush design remains the natural choice for cottages, farmhouses, Georgian and Victorian homes, and any property in a conservation area where sympathetic detailing matters. Traditional casement windows like these were the standard on British homes for hundreds of years before modern profiles arrived.
Why choose a flush casement for a period property?
The appeal comes down to authenticity. Period homes were built with flush casements, so fitting them again preserves the character of the elevation rather than fighting it. For anyone restoring or extending a heritage property, this is often the deciding factor.
There are practical reasons too:
- Slimmer sightlines. The flat profile shows more glass and less frame, letting in more light.
- Timeless proportions. Flush casements suit traditional glazing bar layouts and period ironmongery.
- Conservation friendly. Planning officers tend to favour flush designs in listed and conservation settings, which can smooth the approval process.
If your home sits in a conservation area or is listed, it is worth reading our guide to replacing and restoring windows in listed buildings and conservation areas before you commit to a style.
Do flush casement windows perform well?
Yes. A common myth is that traditional styling means poor efficiency. Modern timber flush casements are engineered with concealed draught seals and can be fitted with high performance double glazing or slim heritage units, so they meet current standards while keeping their period looks.
Because the sash and frame form a tight, even closure, a well made flush casement seals reliably against draughts. Paired with the right glazing, it delivers warmth and noise reduction without the bulk of a stormproof profile. For homes where slim units matter, our vacuum insulated glass offers strong thermal performance in a very thin unit, which is ideal for period frames.
As a FENSA approved installer, we self-certify that every window we fit meets current building regulations, so you receive the compliance certificate without needing separate local authority sign-off.
Timber, uPVC or aluminium?
Flush casements are available in several materials, but they are not equal.
Timber is the original and, for most period homes, the best. It offers the authentic depth and finish that plastic struggles to imitate, it can be repaired rather than replaced, and a well maintained timber window lasts for decades. uPVC flush casements exist but often look flatter and less convincing up close, and they cannot be restored once the frame degrades. Aluminium suits contemporary settings more than heritage ones.
At Tailored Wood we manufacture our casement windows in house in our own Salisbury workshops. That control over section sizes and construction lets us match original profiles precisely, which is difficult to achieve with off-the-shelf products. As a Made in Britain member, we manufacture every window here in the UK rather than importing, and our installations are backed by an insurance-backed guarantee through Quality Assured National Warranties for lasting peace of mind.
What to consider before you buy
A few questions help you brief a joiner properly and avoid costly changes later:
- What period is your home? The right glazing bar layout and sash proportions differ between a Georgian townhouse and a country cottage.
- Are you in a conservation area or listed? This affects both the style and the glazing you are allowed to fit.
- What glazing do you need? Standard double glazing suits most homes, while slim or vacuum units suit tighter period frames.
- Do you want to match existing windows? Bespoke manufacture lets you replicate details across a whole elevation.
- Who will fit them? In house fitting teams protect the quality of the install, which matters as much as the window itself.
How much do flush casement windows cost?
Cost depends on size, timber species, glazing and the number of windows. Bespoke timber windows sit above uPVC on price but last far longer and add more to a period property’s value, which often makes them the better long term investment. For a full breakdown, see our guide to how much timber windows cost.
The bottom line
Flush casement windows give period homes an authentic, elegant finish that modern stormproof profiles cannot match, and modern manufacture means you no longer sacrifice performance for looks. Choose timber, work with a joiner who manufactures to your property’s original proportions, and you will have windows that look right and last for generations.
If you are planning a project, get in touch with Tailored Wood for a free consultation. As a family run heritage joinery just outside Salisbury, we design, make and fit bespoke timber flush casements across the South Coast, and we are happy to talk through the right style for your home.
Our clients tell the story better than we can. As one homeowner in Ringwood put it after we restored and replaced their sash and casement windows: “From start to finish such care and attention goes into their work it was a joy to work with them.”
Alongside our FENSA approval, Made in Britain membership and QANW guarantee, we are members of the Federation of Small Businesses and a CHAS compliant contractor, so you can be confident your project is in accredited, experienced hands.