COR Vision, COR Vision Evolution and COR Vision Plus are Cortizo’s minimal-frame sliding systems. COR Vision has the slimmest 20mm interlock and panels to 2500 × 3000mm. Evolution sits in the middle: 25mm interlock, sashes to 3500 × 3500mm at 500kg and the best Uw of the range at 0.88 W/m²K. COR Vision Plus is the largest format — 4000 × 4000mm panels and glazing to 56mm.
We fabricate Cortizo at our own factory in Slough, so the figures below are not marketing copy — they are Cortizo’s published system data, checked against what we cut, machine and glaze. The three systems are not a good/better/best ladder: each one wins on something.
The three systems at a glance
| System | Choose it for | Key numbers |
|---|---|---|
| COR Vision | The slimmest possible view | 20mm interlock · panels to 2.5 × 3m · double glazing |
| COR Vision Evolution | Best performance and best value for most openings | 25mm interlock · panels to 3.5 × 3.5m at 500kg · Uw from 0.88 · corners without a post |
| COR Vision Plus | The very biggest openings | 25mm interlock · panels to 4 × 4m · glazing to 56mm · motorised to 700kg |
Full specification comparison
| Specification | COR Vision | COR Vision Evolution | COR Vision Plus |
|---|---|---|---|
| Interlock (central junction) | 20mm | 25mm | 25mm |
| Frame depth, 2-track | 116mm | 160mm | 180mm |
| Frame depth, 3-track | 182mm | 248mm | 278mm |
| Maximum panel size | 2500 × 3000mm | 3500 × 3500mm | 4000 × 4000mm (to 14m² glazed) |
| Maximum panel weight | 320kg | 500kg | 400kg manual / 700kg motorised |
| Glazing thickness | 26–30mm | 28–44mm | 36–56mm |
| Thermal transmittance | Uw from 1.3 W/m²K | Uw from 0.88 W/m²K | Uw from 0.9 W/m²K |
| Acoustic performance | Rw to 41dB | Rw to 43dB | Rw to 43dB |
| Air permeability (EN 12207) | Class 4 | Class 4 | Class 4 |
| Watertightness (EN 12208) | Class 7A | Class E900 | Class 7A / 9A |
| Wind resistance (EN 12210) | Class C5 | Class C5 | Class C3 / C4 |
| Visible sash / lateral sightline | 37mm | 62mm | 69mm |
| 90° corner without a post | Yes — inner and outer | Yes — inner and outer | Yes |
| Pocket (into-the-wall) version | Yes, 1–6 sashes | Yes | Yes, 1–4 sashes |
Every figure is from Cortizo’s published technical files (COR Vision, Evolution, Vision Plus). Two things worth flagging. COR Vision Plus panels are capped at 14m² of glass, so the headline 4m × 4m is not available in both directions at once. And the weather classes were not all earned on the same size of test specimen — COR Vision’s C5 wind class comes from a 1.23 × 1.55m reference test, Evolution’s from a full 4.0 × 3.0m two-sash specimen — so ask for the classification at your sizes rather than comparing headline classes across systems.
Which one should you choose?
| Your situation | System | Why |
|---|---|---|
| Slimmest possible view, panels within 2.5 × 3m | COR Vision | The 20mm interlock is at the slim end of the whole market |
| Retrofit into a shallow reveal | COR Vision | A 116mm frame hides where 160mm or 180mm will not |
| Panels up to 3.5 × 3.5m | COR Vision Evolution | 500kg sashes without motorisation |
| Best U-value / triple glazing to 44mm | COR Vision Evolution | Uw from 0.88 W/m²K — the best of the three |
| Best performance for the money | COR Vision Evolution | Matches or beats Plus on every tested class, without the large-format premium |
| Corner with no post | Any of the three | All offer a 90° cornerless sash — panel size and weight decide which |
| Panels beyond 3.5m, or glazing beyond 44mm | COR Vision Plus | To 4 × 4m, 56mm units, 700kg motorised |
| Exposed / high-wind site | Check per system | Vision and Evolution hold C5, Plus C3/C4 — but test specimen sizes differ, so ask for the class at your sizes |
If a supplier answers “whichever you prefer” to those questions, they are selling you a brochure. The opening decides, not taste.
Where does COR Vision Evolution fit?
Evolution is Cortizo’s newest slider and the value pick for most openings: within its 3.5m size ceiling it matches or beats COR Vision Plus on every tested class — and typically comes in below it on cost. Its numbers were achieved on a full-size 4.0 × 3.0m two-sash test specimen, not a small test window.
What is the interlock, and does 5mm matter?
The interlock is the aluminium you see where two sliding panels overlap in the middle of the opening — 20mm on COR Vision, 25mm on the other two. On a well-detailed opening the outer frame is buried in the structure, so the interlock is most of what you actually see. Across a six-panel run the 5mm difference repeats at every junction and adds up to 15mm.
Corners without a post
All three systems now offer a 90-degree corner with no mullion: glass to glass when closed, and the corner disappears entirely when open. Many UK comparison pages still claim the base COR Vision cannot do this — Cortizo’s current technical file says it can, in both inner and outer configurations. The panel sizes and weights at the corner decide which system the drawing calls for, and the structure above must be carried without the corner helping.
Why buy from the fabricator?
Most companies selling these systems are resellers. We fabricate Cortizo in Slough, so a survey correction is a works instruction rather than a change order to a third party — and the specification advice is unfiltered: we will tell you when the smaller, cheaper system is the right answer, because we gain nothing by selling the bigger one. Direct Trade Windows is Constructionline Gold and FENSA registered, with work published in Dezeen.
Where we install Cortizo sliding doors
Ninety-nine orders in our production records specify a COR Vision system, spanning 74 postcode districts across 33 postcode areas nationwide. The densest patches:
Wandsworth and Wimbledon (SW18, SW19, SW20)
Seven projects — mostly side-return and rear extensions on Victorian and Edwardian villas.
Esher, Cobham, Walton and Weybridge (KT11, KT12, KT13)
Seven projects across the Surrey private estates, mostly through developers and architects on knock-down-rebuild plots — including the glazed pavilion in Hersham (KT12) photographed at the top of this page, with COR Vision sliding walls wrapping its corner. Estate hours-of-restriction, gate protocols and vehicle-access rules are routine for our install teams.
East Finchley, Finchley and Whetstone (N2, N3, N20)
Four projects on inter-war and Edwardian family houses. In N2, Hampstead Garden Suburb properties need Trust consent as well as council planning — two separate processes.
Berkhamsted and the Chilterns (HP1, HP4, HP6, HP7)
Four projects. In Berkhamsted’s conservation-controlled centre, the rear elevation is usually where modern glazing is allowed to happen.
Slough and Maidenhead (SL1, SL6)
Three projects on the factory’s own doorstep, including the Fisheries Estate riverside pocket at Bray.
Hove (BN3)
Two projects on Regency and Victorian stock — and a coastal site is a good reason to check the wind and watertightness rows in the table above.
Where to go next
Full specifications and finishes are on the Cortizo COR Vision sliding door and Cortizo COR Vision Plus sliding door pages; we fabricate COR Vision Evolution to the same specification service — ask us for the system data sheet. The slimline aluminium sliding doors overview sets the range alongside the Cortizo 4600 and 4700 systems.
Send us the opening, not the product name
Give us the structural opening size, the reveal depth and whether a corner is involved, and we will tell you which Cortizo system the drawing actually calls for — including when it is the smaller one.
