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 are conventional in-line aluminium patio sliders. The difference between them is thermal specification, and choosing correctly saves money in one direction and future-proofs the house in the other. 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 in-line slider: robust aluminium profile, smooth-running gear, clean contemporary lines, available in the full RAL colour palette. For a typical two- or three-panel 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 the thermally enhanced sibling. Cortizo positions the 4900 as a slider with casement-like thermal and acoustic performance: the thermal break inside the profile is upgraded, cutting the heat that escapes through the frame itself. The glass area of any patio door dominates its overall performance, but on large openings the frame fraction still matters, and the 4900 tightens exactly that.

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 as three tiers: 4700 for value, 4900 for thermal headroom, Cor Vision for maximum glass.

Thermal Performance: Where the 4900 Earns Its Keep

Both systems take A-rated double glazing and meet current Building Regulations when specified properly. The 4900's upgraded thermal break gives it more headroom: with high-specification glazing it reaches lower whole-door U-values than the 4700 can, which matters in three situations.

1. Large glazed openings. The bigger the door, the more the frame's performance contributes to the room's heat loss. On a wide three- or four-panel opening, the HI break pays its way every winter. 2. Highly glazed extensions. If the door is one element of a mostly-glass rear elevation, the cumulative frame area is significant and the better break shifts the whole calculation. 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 the 4900 buys margin.

For a modest two-panel opening in a well-insulated house, the 4700 specified with good glass performs perfectly 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 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 — and our sliding vs bifold 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 opening is modest, the house is thermally ordinary, and value matters. It is the sensible default for a standard patio replacement, and money saved on the frame is often better spent on upgraded glass.

Choose the 4900 Sliding HI when the opening is large, the extension is heavily glazed, or you want performance headroom against tightening regulations. 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 in-line aluminium patio sliders from Cortizo. The 4900 Sliding HI carries an upgraded high-insulation thermal break inside the profile, giving it better whole-door thermal performance than the 4700 Sliding Patio, particularly on large openings paired with high-specification glazing. The 4700 is the value choice for standard openings; the 4900 buys thermal headroom.

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

On large or heavily glazed openings, yes: the frame's share of heat loss grows with door size, and the HI thermal break addresses exactly that, while also buying margin against tightening Building Regulations. On a modest two-panel opening in a well-insulated home, the 4700 with good glazing performs well and the saving is better spent elsewhere.

Are Cortizo 4700 and 4900 doors secure?

Both systems run multi-point locking as standard and 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.