UK · 2026 Spec
What's the Slimmest Sliding Door in the UK?
The direct answer
Short answer
Cortizo COR Vision Sliding has the narrowest published central junction of any mainstream aluminium sliding door in the UK, at 20mm. Apex fits that same system as APX20 Ultra Slim. Cortizo's larger COR Vision Plus Sliding, which Apex fits as APX20 Plus, sits at 25mm. Schüco publishes a 40mm interlock face width on the ASE 60 and ASE 80.HI Design Line, and Reynaers MasterPatio publishes a 50mm chicane.
"Slimline" refers to the visible vertical bar where two panes meet, which Cortizo calls the central junction and Schüco calls the interlock face width. Narrower means more glass and less frame at eye level. Be careful comparing across brands, because they do not all measure the same thing: Origin publishes a "sightline" of 29mm for its OS29+ but publishes no interlock dimension at all, so the two numbers are not like-for-like.
UK slimline sliding door ranking
Sorted by the manufacturer's own published figure for the vertical bar where two panes meet. Where a manufacturer does not publish a figure, the cell says so rather than carrying an estimate.
| System | Central junction / interlock | Max sash (W × H) | Max weight |
|---|---|---|---|
| Cortizo COR Vision Sliding (Apex APX20 Ultra Slim) | 20 mm | 2500 × 3000 mm | 320 kg |
| Cortizo COR Vision Plus Sliding (Apex APX20 Plus) | 25 mm | 4000 × 4000 mm | 400 kg manual |
| Schüco ASE 60 | 40 mm Design Line | 3500 × 3500 mm | 500 kg |
| Schüco ASE 80.HI | 40 mm Design Line | 3500 × 3500 mm | 500 kg |
| Cortizo 4700 Sliding (Apex APX47) | 50 mm sash | 2500 × 3000 mm | 300 kg |
| Reynaers MasterPatio | 50 mm chicane | 3000 × 3600 mm | 600 kg slider |
| Smart Visoglide Plus | 83 mm | 2500 mm high | 250 kg |
| Origin OS29+ / OS44 / OS77 | Not published | 2200 × 2520 mm | Not published |
Sources: Cortizo COR Vision Sliding, COR Vision Plus Sliding and 4700 Sliding system data sheets; Schüco ASE 60 / ASE 80.HI system brochure; Reynaers MasterPatio brochure; Smart Systems Visoglide Plus data sheet IMS129VGP; Origin sliding door pages. Origin publishes a sightline of 29 / 44 / 77 mm for OS29+ / OS44 / OS77 but no interlock dimension and no panel weight, so those cells are left as not published rather than estimated.
Spec breakdown, top five systems
Manufacturer-published detail for the five systems Apex fits most often. Every figure below is a published maximum or a published "from" value, not a project-specific result. APX20 Ultra Slim, APX20 Plus and APX47 are Apex-badged builds of the Cortizo COR Vision Sliding, COR Vision Plus Sliding and 4700 Sliding systems.
| Spec | APX20 Ultra Slim | APX20 Plus | Schüco ASE 60 | Schüco ASE 80.HI | APX47 |
|---|---|---|---|---|---|
| Central junction / interlock | 20 mm | 25 mm | 40 / 102 mm | 40 / 102 mm | 50 mm sash |
| U-value, from | 1.3 | 0.9 | 1.1 | 0.99 | 1.0 |
| Max sash (W × H) | 2500 × 3000 mm | 4000 × 4000 mm | 3500 × 3500 mm | 3500 × 3500 mm | 2500 × 3000 mm |
| Max sash weight | 320 kg | 400 kg manual | 500 kg | 500 kg | 300 kg |
| Sash depth | 37 mm | 69 mm | 60 mm | 80 mm | 50 mm |
| Glazing thickness | 26-30 mm | 36-56 mm | 24-46.5 mm | 28-60 mm | 26-36 mm |
| Security | PAS 24 available | PAS 24 available | Up to RC2 | Up to RC3 | PAS 24 available |
| Acoustic Rw, up to | 43 dB | 43 dB | 41 dB | 43 dB | 40 dB |
| Watertightness | Class 7A | Class 9A | Not published | Not published | Class 7A |
Why 20mm matters
A 20mm junction against a 50mm one makes a visible difference in any real opening. The arithmetic is simple: every junction in the run costs you that much aluminium at eye level, so the effect compounds with each extra pane.
| Configuration | At a 50mm junction | At a 20mm junction |
|---|---|---|
| 2-pane, one junction | 50 mm of frame at eye level | 20 mm of frame at eye level |
| 3-pane, two junctions | 100 mm of frame | 40 mm of frame |
| 4-pane, three junctions | 150 mm of frame | 60 mm of frame |
Frequently asked
What's the slimmest sliding door in the UK?
Cortizo COR Vision Sliding, which Apex fits as APX20 Ultra Slim, has the narrowest published central junction of any mainstream aluminium sliding door in the UK at 20mm. Cortizo's larger COR Vision Plus Sliding, fitted by Apex as APX20 Plus, sits at 25mm. Schüco publishes a 40mm interlock face width for the ASE 60 and ASE 80.HI Design Line, Reynaers publishes a 50mm chicane on MasterPatio, and Smart Systems publishes an 83mm interlock on Visoglide Plus.
Is a 20mm central junction real?
Yes. Cortizo publishes 20mm as the central junction for COR Vision Sliding on its own system data sheet, alongside a 37mm sash depth and a 116mm frame. The figure refers to the visible vertical bar where two sashes overlap. It is worth confirming what a supplier is measuring, because some quote a face-on dimension that thickens when you view the door from an angle, and some quote a sightline rather than an interlock.
Does APX20 Plus have a 20mm junction?
No, and this is a common mix-up. APX20 Plus is Apex's build of Cortizo COR Vision Plus Sliding, which publishes a 25mm central junction. It is the larger, heavier-duty system: sashes up to 4000 × 4000mm, up to 400kg by hand or 700kg motorised, glazing from 36 to 56mm and a U-value from 0.9 W/m²K. If the 20mm junction is what you want, the system is APX20 Ultra Slim.
Is Cortizo COR Vision available in the UK?
Yes. Cortizo COR Vision Sliding is available in the UK through Cortizo's fabrication network. Apex Glazing installs the system across London and the South East, powder coated to any RAL colour, and handles survey, structural check, fitting and FENSA self-certification under Reg 40373.
How much does a slimline sliding door cost?
Slimline sliding doors are made to order, so the cost depends on the size of the structural opening, the number of panes, the glass specification, the threshold detail, the colour and site access. We quote after a survey rather than from a price list. What we can tell you before a survey is which system your opening actually needs, which is usually the more useful answer.
What U-value does Cortizo COR Vision have?
Cortizo publishes a whole-window U-value from 1.3 W/m²K for COR Vision Sliding, with a glazing thickness of 26 to 30mm. The larger COR Vision Plus Sliding is published from 0.9 W/m²K, because its deeper 69mm sash takes glazing up to 56mm. Approved Document L sets the limiting standard for a replacement door in an existing dwelling at 1.4 W/m²K, so both are compliant.
How big can slimline sliding panes be?
Cortizo publishes a maximum sash of 2500mm wide × 3000mm high at 320kg for COR Vision Sliding, and 4000 × 4000mm at 400kg manually operated, or 700kg motorised, for COR Vision Plus Sliding. Schüco publishes 3500 × 3500mm at up to 500kg for ASE 60 and ASE 80.HI. Achievable size on any given project also depends on glass specification, wind exposure and the structural opening.
Are slimline sliding doors PAS 24 secure?
PAS 24 is available on the Cortizo COR Vision systems and Apex's APX20 range, and Cortizo publishes a passed PAS 24 security test on its sliding range. Schüco publishes burglar resistance up to RC2 to BS EN 1627 for ASE 60 and up to RC3 for ASE 80.HI. PAS 24 is a specification you order the door to rather than something every unit carries by default, so make sure it is written on the quote.
