What are corner sliding doors?
A corner sliding door is a sliding door system that runs along two walls meeting at a right angle, with the sliding panels on each side closing against each other at the corner instead of against a post. When both sets of panels are slid back, the corner itself is open, so the room flows straight out to the garden at its most open point. When closed, the two meeting panels lock together, leaving a slim junction at the corner rather than a structural column.
Because there is no post, the load from the wall or roof above the corner has to be carried another way, usually by a cantilevered steel beam or a steel frame designed by a structural engineer and approved under the Building Regulations. That makes corner sliders mainly a choice for new extensions, garden rooms and major refurbishments, where the steelwork is designed in from the start. They suit kitchen-diners and living spaces that wrap around a garden or terrace.
Price is set by the combined width of both elevations, the number of panels, height, glass and finish. Guide prices include the door, fitting and structural calculations; the steelwork that supports the corner is priced after survey because it depends entirely on the building. We survey free, coordinate the door with the engineer's design and fix both in a written quote before ordering.
Who are they for?
Best suited to
- New extensions and garden rooms
- Kitchen-diners that wrap around a garden
- Opening a room's corner to a terrace
- Projects with engineered steelwork planned in
Worth considering
- A post-free corner needs structural support above, usually engineered steelwork, which adds cost and design time.
- Corner systems are rarely a straight swap; they normally go into new or rebuilt openings.
- Combined widths are large, so lead times, delivery and fitting need more planning than a single straight door.
Why choose corner sliding doors?
- With no post at the corner, sliding both sets of panels back opens the meeting point of two walls completely, so the room spills straight onto the patio.
- Daylight reaches the room from two directions, which keeps a deep extension brighter through the day as the sun moves round the house.
- When closed, the two corner panels interlock and lock together, so the glass corner stays weathertight and secure without a visible column.
- Each elevation can have its own number of panels and its own sliding direction, letting the opening suit the shape of the garden and the furniture layout.
- A corner of glass gives a much wider field of view than a single straight door, taking in more of the garden from a seat inside.
- Corner systems use thermally broken aluminium sections with slim sightlines and powder-coated finishes, so the frames stay discreet on both walls.
- Because panels slide rather than fold, the corner can be opened on one side only, keeping the other side closed as a wind screen on cooler days.
- Low or flush thresholds can run around both elevations, giving one continuous level line from the floor inside to a terrace that wraps the corner.
Typical specification
| Combined width (our range) | About 3 m to 8 m across both elevations |
|---|---|
| Panels | Typically four panels up to about 4.8 m combined; six panels for wider corners |
| Corner detail | Post-free; meeting panels interlock and lock together |
| Structural support | Cantilevered steel or steel frame designed by a structural engineer |
| Typical panel height | Standard 2.1 m; taller depending on system |
| Typical whole-door U-value | Around 1.2–1.6 W/m²K double glazed, depending on system |
| Threshold | Low at around 15–25 mm, or flush with external drainage |
| Security | Multi-point locking including the corner junction; systems available tested to PAS 24 |
Figures are typical and vary by system and size; your quote confirms the exact specification.
How much do corner sliding doors cost?
As a guide price, a corner door with 4 m of combined width across both walls is £10,295–£12,495 fitted, inc VAT, at standard 2.1 m height; 6 m combined is around £13,395.
| Overall width | Typical panels | Guide price (fitted, inc VAT) |
|---|---|---|
| 3.0 m | 4 panels | £8,695–£10,595 |
| 3.6 m | 4 panels | £9,595–£11,795 |
| 4.0 m | 4 panels | £10,295–£12,495 |
| 4.8 m | 4 panels | £11,495–£13,995 |
| 6.0 m | 6 panels | £13,395–£16,295 |
| 8.0 m | 6 panels | £16,495–£20,095 |
Guide prices for a standard 2.1 m high door, supplied and fitted, including structural calculations and VAT. The steelwork that supports the corner is designed by the engineer and priced after survey, because it depends on the building. Your price is fixed in a written quote after survey.
Options and extras
- System type. Standard aluminium, slimline or lift and slide corner systems, depending on panel size and the sightlines you want.
- Panel layout. Two panels per side for smaller corners or three per side for wider ones, with fixed panels at the far ends.
- Glass. Double or triple glazed safety glass, with solar-control coatings for corners facing south or west.
- Colours. Single or dual colour powder coating, so the outside can match the extension cladding or render.
- Threshold. Standard, low or flush thresholds, with drainage detailed along both elevations.
- Roof junction. Head details coordinated with flat roofs, roof lanterns or pitched roofs so steel, frame and roof meet neatly.
Lead times and fitting
Lead time: Typically 4–6 weeks for aluminium, 6–8 weeks for slimline or lift and slide corners, from survey sign-off.
Fitting: Typically 1–2 days for the door, after 3–5 days of structural building work.
Nothing is ordered until you confirm the surveyed specification in writing. See how it works.
Rules and approvals
England
In England, forming or widening an opening is structural work that needs a Building Regulations application, structural calculations and usually a steel beam on padstones. The new door is also a controlled fitting (U-value 1.4 W/m²K or better if more than 60% glazed). If steelwork bears on a party wall, the Party Wall etc. Act 1996 may apply.
Wales
In Wales, structural work to form or widen an opening needs Building Regulations approval and structural calculations, and the new door must meet the Welsh energy and safety glazing requirements. The Party Wall etc. Act 1996 may apply where steelwork bears on a party wall.
Scotland
In Scotland, forming or widening an opening needs a building warrant before work starts, with structural details for the new beam. The door must meet the Scottish building standards for energy and safety glazing.
Northern Ireland
In Northern Ireland, structural alterations need approval from your district council's building control service before work starts. New openings in Northern Ireland are by arrangement.
Corner sliding doors: common questions
How much do corner sliding doors cost?
Corner sliding doors start from a guide price of £8,695 for 3 m of combined width across both walls, fitted, inc VAT, at standard 2.1 m height. A 4.8 m combined corner is a guide £11,495–£13,995, and 8 m combined is around £16,495. Structural steel for the post-free corner is priced separately, and the final price is fixed in a written quote after survey.
Do corner sliding doors need a steel beam?
Corner sliding doors almost always need engineered structural support, because removing the corner post takes away the support for the wall or roof above. A structural engineer designs a cantilevered beam or steel frame; the calculations are included in our guide prices and the steelwork is priced after survey. In England this needs a Building Regulations application and in Scotland a building warrant; Wales and Northern Ireland have their own building control rules.
How big can a corner sliding door be?
A corner sliding door in our range typically covers about 3 m to 8 m of combined width across both walls, usually four panels up to about 4.8 m and six panels above that. The two sides do not need to be equal. Panel height starts at the standard 2.1 m and can go taller depending on the system, which is confirmed at survey alongside the structural design.
How long does a corner sliding door project take?
A corner sliding door typically takes 4–6 weeks to manufacture in standard aluminium and 6–8 weeks for slimline or lift and slide systems, from survey sign-off. The steelwork and building work usually take 3–5 days before the door goes in, and fitting the door takes 1–2 days. Engineer design and approvals come first, so the door is ordered once the steel is designed.
Is the open corner a weak point for security?
The corner of a corner sliding door is not a weak point when the system is properly specified, because the two meeting panels interlock and lock together, typically with multi-point hardware at the corner as well as on the sliding edges. Laminated glass adds resistance to breaking through. Corner systems are available tested to PAS 24, and the locking specification is confirmed in your quote.
Do corner sliding doors lose more heat?
Corner sliding doors lose heat in proportion to their glazed area, so a large glass corner loses more than a solid wall would, but thermally broken systems keep typical whole-door U-values around 1.2–1.6 W/m²K double glazed. In England, a new door in an existing home with more than 60% glazing must achieve 1.4 W/m²K or better, and triple glazing is available. Wales, Scotland and Northern Ireland apply their own energy rules.
How do you maintain a corner sliding door?
Maintaining a corner sliding door is much like any aluminium slider, with extra attention to the corner: keep both tracks and the corner drainage clear, wipe the corner seals, and check the meeting panels still lock smoothly. Rollers can be adjusted if a panel drops. Because a new extension can settle slightly in its first year, the corner panels may need a small adjustment after that.
Can I add a corner sliding door to an existing house?
A corner sliding door can be added to an existing house, but it is a structural project rather than a door swap: the corner of the building has to be rebuilt with engineered steel to carry the load where the post or wall used to be. It is usually done as part of an extension or rear remodel, and a survey plus an engineer's assessment confirm what the structure above needs.