Cortizo 4700 vs 4900 Sliding Doors: Which System to Choose?

Cortizo's sliding door range runs deeper than most buyers realise, and two systems in the middle of it — the 4700 Sliding Patio and the 4900 Sliding HI — are where a large share of real-world projects land. Both run as conventional in-line aluminium sliders, and the 4700 also comes in a lift-and-slide version. The difference between them is how each is engineered: the 4700 for larger, heavier panels and the better U-value, the 4900 for a slimmer junction and a tighter air seal. Choosing correctly means matching that to the opening. As a manufacturer and fabricator of Cortizo systems at our Uxbridge workshop, we build and fit both, so this comparison comes from the bench as well as the brochure.

The Two Systems in Brief

Cortizo 4700 Sliding Patio is the range's workhorse slider, available in-line or as a lift-and-slide version: robust aluminium profile, sashes up to 2.5m wide by 3m high (280kg in-line, 300kg lift-and-slide), double glazing from 26mm to 36mm and Uw from 1.0 W/m²K, in the full RAL colour palette. For a typical patio opening onto a garden, the 4700 does everything most households ask of a sliding door and does it at the most accessible point in the aluminium range.

Cortizo 4900 Sliding HI is an in-line sliding window and door system that Cortizo positions as a standard slider with casement-like performance. Its strengths are a slimmer 35mm central junction (against the 4700's 47mm interlock), class 4 air-tightness, multi-point locking and more track layouts, including 4-track. Sashes run up to 2.2m wide by 3m high at 240kg, with glazing from 24mm to 36mm and Uw from 1.2 W/m²K.

Neither of these is Cortizo's slim-sightline flagship. That is the Cor Vision family, which trims the visible interlock to a minimal line and carries a price to match — we compared those two systems in Cor Vision vs Cor Vision Plus. Think of the range this way: 4700 for large, heavy panels and lift-and-slide, 4900 for a finer junction and a tighter seal, Cor Vision for maximum glass.

Thermal Performance and Air-Tightness: Where Each Earns Its Keep

Both systems take A-rated double glazing and meet current Building Regulations when specified properly, and both are rated for sound reduction up to Rw 40dB. Where they differ on performance, the split matters in three situations.

1. Insulation. The 4700 reaches Uw from 1.0 W/m²K and the 4900 from 1.2 W/m²K, so where the U-value is the deciding figure, the 4700 is the stronger system. 2. Exposed elevations. The 4900 reaches class 4 air-tightness, which makes it the better choice on a windswept, draught-prone elevation. 3. Future regulation. UK Building Regulations continue to tighten, as our guide to the Future Homes Standard explains. A door bought once should clear the bar for decades, and on U-value the 4700 gives more margin.

For a modest opening in a sheltered spot, either system specified with good glass performs well, and the difference in running cost is small. Our U-value explainer covers how to read the figures on a quote.

Everything the Two Systems Share

Because both are Cortizo in-line sliders, most of the buying decision is identical:

• Configurations from two panels up, with fixed-and-sliding combinations to suit the opening
• Full RAL colour range in powder-coat, including dual-colour inside/out
• Multi-point locking, with PAS 24 specification available on the 4700 where Approved Document Q applies — see our guide to secure door standards
• The same fabrication and fitting quality. We machine and assemble both systems in the same Uxbridge workshop, and every installation is FENSA registered with a 10-year CPA insurance-backed guarantee

Sliding doors as a category also share trade-offs against bifolds: a slider gives bigger uninterrupted glass, a bifold gives a fuller opening. Our bifold vs sliding vs French doors comparison walks through that decision if you have not yet settled the door type itself.

How to Choose

Choose the 4700 Sliding Patio when the panels are large or heavy (sashes up to 2.5m by 3m), you want lift-and-slide operation, the lower U-value is the priority, or the project needs a PAS 24 door. It is also the sensible default for a standard patio replacement where value matters.

Choose the 4900 Sliding HI when the sashes sit within its 2.2m by 3m limit and you want a slimmer 35mm central junction, class 4 air-tightness on an exposed elevation, or a 4-track layout. The premium over the 4700 is a fraction of the project cost and permanent.

Look at Cor Vision instead when the brief is architectural: minimal sightlines, panoramic glass, the frame almost disappearing. That is a different budget conversation, covered in our Cortizo sliding doors review and cost guide.

Whichever way the choice falls, the right answer starts with the opening itself: span, exposure, orientation and how the room is used. Book a free survey and we will measure, recommend the tier honestly and quote it as the fabricator — we cover London, Buckinghamshire, Berkshire and the surrounding counties. The full range is on our Cortizo brand page and the aluminium sliding doors page.

Frequently Asked Questions

What is the difference between the Cortizo 4700 and 4900 sliding doors?

Both are aluminium sliders from Cortizo, and the 4700 Sliding Patio also comes in a lift-and-slide version. The 4700 takes larger, heavier sashes (up to 2.5m by 3m, at 280kg in-line or 300kg lift-and-slide) and has the better U-value, from 1.0 W/m²K. The 4900 Sliding HI is in-line only, with sashes up to 2.2m by 3m at 240kg and Uw from 1.2 W/m²K, and it offers a slimmer 35mm central junction, class 4 air-tightness and more track layouts, including 4-track. Both reach Rw 40dB for sound reduction.

Is the Cortizo 4900 HI worth the extra cost over the 4700?

It depends on what the opening needs. The 4900 is worth it where a slimmer 35mm junction, class 4 air-tightness on an exposed elevation or a 4-track layout matters. For a very large opening, or where the lower U-value is the goal, the 4700 is the better buy, with bigger sashes and Uw from 1.0 W/m²K, and the saving can go on upgraded glass.

Are Cortizo 4700 and 4900 doors secure?

Both systems run multi-point locking as standard, and the 4700 can be specified to PAS 24 where Approved Document Q compliance is required, such as new dwellings. Fitted correctly by a FENSA-registered installer, an aluminium in-line slider is a secure door type, with no external track accessible for lifting when locked.

Who makes Cortizo sliding doors in the UK?

Cortizo extrudes the aluminium profile in Spain, and approved fabricators machine and assemble it into finished doors. Vitrum Solutions is a manufacturer and fabricator of Cortizo systems at our Uxbridge workshop as well as the installer, so the doors we fit are doors we built, backed by a 10-year CPA insurance-backed guarantee.

Should I choose a Cortizo slider or a bifold instead?

A slider gives larger uninterrupted panes and a cleaner glass wall when closed; a bifold folds almost fully out of the way and gives the wider clear opening. Cortizo makes both, we fabricate both, and the honest answer depends on how you use the room — our sliding vs bifold comparison covers the decision in full.