Windows
Flush casement windows
A flush casement sits level with the outer frame rather than overlapping it, giving the clean line of a traditional timber window. It costs more than a standard stormproof casement and is often the compromise that gets modern materials accepted on a period property.
The difference between a flush and a stormproof casement is about fifteen millimetres, and it is the fifteen millimetres that make a window look either contemporary or traditional.
Indicative guide, not a quote
per window, supplied and fitted
£400 – £850
These figures come from published industry price guides, not official statistics, and several of those sources are installers or comparison sites with a commercial interest. They are a starting point for a conversation, not a quote. Your installer sets the actual price after measuring.
Costwise UK new windows cost guide · checked 2026-10-09
What flush actually means
On a stormproof casement the opening sash is slightly larger than the aperture and laps over the frame, so you see a step from outside. On a flush casement the sash sits within the frame so the two faces align, which is how traditional timber windows were made.
From the street the flush version reads as a much quieter window. On a period elevation that difference is the whole point.
Weathering, and the honest trade-off
The lip on a stormproof casement exists for a reason: it sheds water away from the joint. A flush casement relies on its gaskets and drainage instead, which modern systems handle well, but it is a more demanding detail.
On a very exposed elevation this is worth discussing rather than assuming.
Where it earns its cost
Flush casement windows: common questions
- Is a flush casement worth the extra cost?
- On a period property, usually yes, because it is the detail that makes the window look right. On a modern house the visual difference is far less significant.
- Are flush casements available in uPVC?
- Yes. Several systems offer a flush profile, often with a woodgrain foil, specifically for properties where a standard stormproof window would look out of place.
- Do flush casements leak more?
- Not when correctly specified and fitted. They rely on gasket and drainage design rather than an overlapping lip, so fitting quality matters more than it does on a stormproof window.
Other windows
- The default choice
uPVC windows
uPVC windows cost £400 to £850 fitted.
£400 – £850
fitted, guide only
- Slimmest frames
Aluminium windows
Aluminium windows cost £600 to £1,250 fitted.
£600 – £1,250
fitted, guide only
- Listed and conservation
Timber windows
Timber windows cost £800 to £1,600 fitted.
£800 – £1,600
fitted, guide only
- Most common UK style
Casement windows
Casement windows are the most common UK style and the cheapest to replace.
£400 – £850
fitted, guide only
- Georgian to Edwardian
Sash windows
Sash windows cost £800 to £1,800 fitted.
£800 – £1,800
fitted, guide only
- Flats and upper floors
Tilt and turn windows
Tilt and turn windows open two ways: a secure vent, or fully inwards for cleaning and escape.
£400 – £850
fitted, guide only
TrustedGlazing does not make, supply or fit windows and doors, and the prices above are published industry guides rather than our own. We match your enquiry to one local installer, who quotes and contracts with you directly.