Flush vs Standard Casement Windows

Standard (sculptured) casement windows have a sash that sits proud of the outer frame by 10–15mm — the classic modern uPVC look. Flush casements have a sash that sits level with the outer frame, matching the appearance of traditional timber windows. From ten paces, a flush uPVC is genuinely hard to distinguish from painted timber.

Conservation areas, listed buildings, period properties (Georgian to 1930s), and heritage-conscious clients who want modern performance in a traditional aesthetic. On a 1970s or later property, flush casements look mannered and unnecessary — standard casements sit better.

Flush casements typically cost 15–25% more than equivalent sculptured casements. The tighter tolerances, more complex profile and dedicated hardware (mechanically jointed corners, flag hinges) drive the extra cost. For a full-house replacement in a period property, budget accordingly.

Flush casement systems (Residence 9, Rehau Rio, Eurocell Modus Flush) come in a wide range of woodgrain and RAL colours. Painted-look finishes (Chalk White, Grained White, Painswick, Anthracite) are the most convincing on period properties. Dual-colour options (white inside, colour outside) are standard.

For genuine heritage settings and listed buildings, timber flush casements remain the correct answer — often with slimline double glazing to satisfy planners. uPVC flush casements are a compromise: modern performance, near-period look, no planning complications on non-listed properties.