uPVC Window Styles Explained
All 17 made-to-measure configurations we supply — how each one works, where it fits, and the size range it covers.
Every style below is available in white Rehau Total 70 profile, A+ energy rated, with fire escape hinges, multi-point locking and a 10-year guarantee included as standard. Prices start from around £117 and scale with size.
Terminology: How Windows Are Described
Before the styles themselves, a quick glossary. It saves confusion when you are comparing quotes from different suppliers.
- Light — a single glazed panel. A "2-light" window has two side-by-side panels; a "3-light" has three.
- Sash — the part that opens. Some lights are fixed (do not open), others are sash.
- Top hung — opens outwards, hinged at the top. Common in kitchens, bathrooms and above doors.
- Side hung — opens outwards, hinged on the left or right. Also called a "casement".
- Transom — the horizontal bar dividing a window into top and bottom sections. A "top hung transom" is a narrow opening pane above a larger fixed or sash pane.
- Fixed light — does not open. Used where ventilation is not needed, or paired with sash lights to reduce cost.
Single Light Windows
Top Hung
400–1400mm wide × 400–1300mm tall
The most versatile single-light style. Opens outwards from the bottom edge, hinged at the top. Good for rainy-day ventilation because rain runs off the open sash rather than into the room.
Best for: kitchens above the sink, bathrooms, first-floor windows above ground level where a side hung would be harder to reach.
Side Hung
400–700mm wide × 400–1400mm tall
The traditional casement window. Hinged on one side (left or right) and opens outwards. Provides the widest unobstructed opening for the frame size, which matters for fire escape compliance in bedrooms.
Best for: habitable rooms at first floor and above where fire escape egress is required, and any narrow-tall opening where a top hung would look squat.
Top Hung with Transom
400–1400mm wide × 800–2000mm tall
A narrow top hung pane above a large fixed lower pane. Delivers ventilation without sacrificing view, since most of the glass area is unobstructed by a sash frame.
Best for: living rooms and dining rooms where you want the view to dominate and you only need light background ventilation.
Top Hung with Top Hung Transom (Tall)
400–1300mm wide × 800–2400mm tall
Two stacked top hung sashes: a small transom pane at the top and a full-height top hung below. Used where you need ventilation at two levels in a tall narrow opening.
Best for: stairwells, tall narrow hallways, Victorian proportion openings in period properties.
Side Hung with Fixed Transom (Narrow Tall)
400–700mm wide × 800–1800mm tall
A tall narrow window with a fixed pane at the top and a full-height side hung sash below. Maximises the opening area for a small footprint.
Best for: utility rooms, W/Cs, narrow back-addition windows.
2-Light Windows
2-Light: Fixed & Side Hung
600–2000mm wide × 600–1400mm tall
The workhorse of modern UK replacement window work. One large fixed pane paired with a side hung sash for ventilation. Cheaper than two opening sashes and lets more light through.
Best for: lounges, bedrooms, any medium-to-wide opening where one sash is enough.
2-Light: Side Hung & Side Hung (French)
800–1500mm wide × 600–1400mm tall
Two side hung sashes hinged on opposite edges, meeting in the middle. When both are open you get a genuinely wide clear opening. Often called a French casement.
Best for: bedrooms where you want the option to fully open the window onto a Juliet balcony or clear opening, and for fire escape where single-sash egress is marginal.
2-Light with Top Hung Transoms (Wide)
700–2400mm wide × 800–2000mm tall
A wide traditional-look window with two narrow top hung transoms above two large fixed lower panes. Maximises view and daylight with ventilation kept at eye level.
Best for: lounges in 1930s bay-style houses, dining rooms, large feature windows.
2-Light Asymmetric with Transom
700–2000mm wide × 800–1800mm tall
Asymmetric configuration: a top hung transom over a fixed pane on one side, paired with a full-height side hung sash on the other. Reads like a 3-light but costs less.
Best for: kitchens and dining rooms where you want generous fixed glazing for view plus a large opening sash for ventilation.
2-Light with Side Hung & Transom
800–2000mm wide × 800–1400mm tall
A full-height side hung sash paired with a narrow top hung transom over a fixed pane. The balance of opening sash to fixed glass changes the feel of the room compared to a straight fixed-and-sash.
Best for: living rooms where the fire escape sash is required but the second half of the opening is for view and light.
2-Light with Top Hung Transoms & Side Hung
800–1500mm wide × 800–1700mm tall
Two stacked lights either side: top hung transom over side hung sash on both halves. Maximum opening area of any 2-light in the range.
Best for: master bedrooms, rooms where cross-ventilation matters, properties near busy roads where the ability to open a small vent at the top while keeping the main sash closed matters.
2-Light Asymmetric with Side Transom
800–1800mm wide × 800–1700mm tall
A large fixed pane on one side paired with a stacked top hung transom and side hung sash on the other. Useful when the opening is wider than a standard 2-light but you do not need a full 3-light.
Best for: awkward intermediate widths, bay side returns, back-addition windows.
2-Light with Transom (Wide)
1400–2400mm wide × 800–1700mm tall
A wide 2-light with a top hung transom and side hung sash on one side, a large fixed pane on the other. At the upper end of the range it reads almost like a 3-light.
Best for: front-room bay replacements where one single wide 2-light replaces two narrower lights from the original window.
3-Light Windows
3-Light: Side Hung & Fixed
1400–2200mm wide × 800–1400mm tall
The classic modern picture window: side hung sash, large central fixed pane, side hung sash. Symmetrical, well-ventilated, maximum fixed glass area in the middle for the view.
Best for: living rooms and kitchens with a wide single opening, front elevations on 1970s and later housing.
3-Light with Central Transom
1400–2000mm wide × 800–1400mm tall
A side hung sash on each side and a top hung transom over a fixed pane in the middle. Gives the same wide view as a plain 3-light, with the addition of trickle ventilation that does not need the main sashes opened.
Best for: main bedrooms, lounges with a TV wall opposite the window where full sash opening is rarely needed.
3-Light with Transoms (Wide)
1400–2400mm wide × 800–1700mm tall
Three sets of stacked lights: top hung transoms above fixed or sash panes across the full width. Tall, traditional proportion, lots of glass.
Best for: period replacements, feature front-room windows, properties with tall original openings.
3-Light with Central Top Hung Transom
1400–2000mm wide × 800–1700mm tall
Two top hung transoms flanking a central section, with side hung sashes below. Designed to match the proportions of original Victorian and Edwardian window openings that are both tall and wide.
Best for: bay window replacements in Victorian and Edwardian properties, front-room feature windows.
How to Choose Between Them
A few rules of thumb that shortcut a lot of deliberation:
- Match the original proportions where possible. If the opening is tall and narrow, pick a tall narrow style rather than trying to force a 2-light into a 600mm-wide gap.
- Check fire escape requirements. Habitable rooms at first floor and above need an openable sash at least 450×450mm clear. Side hung sashes usually comply; small top hungs may not.
- More sashes = more cost. A 3-Light with Fixed & Side Hung is cheaper than a 3-Light with Transoms, even at the same size, because there is less hardware.
- Fixed glass delivers the best view. If the window faces a garden you want to look at, maximise the fixed-light area and keep sashes for ventilation rather than view.
For more detail on any of these styles, see our uPVC buying guide or call 0800 861 1450 with your opening sizes and we will recommend a configuration.
Rehau Windows in Real Homes
The line-art illustrations above show configuration and hinge direction. Below are photographs of the same Rehau Total 70 profile in finished domestic installations.
Don’t See Your Style?
The 17 styles above cover the vast majority of replacement window openings in UK homes, but they are not everything we can make. We also supply bay and bow windows, arched and shaped frames, French and bifold doors, coloured frames (anthracite, Chartwell green, rosewood and more), triple glazing and larger-than-standard sizes. Get a written quote within one working day — no sales call, no obligation.
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