Best Aluminium Bifold Door Systems UK: 6 Compared

Ask which aluminium bifold door is best and you'll get a list of brand names: Cortizo, Origin, Schüco, Smart Systems, AluK, Reynaers. This guide puts those six side by side using the figures each brand publishes about its own bifold system, so you can compare them on the things that decide how a door looks and performs.

It's written for homeowners planning an extension or renovation, and for the builders, installers and architects who specify bifolds for them. We should be upfront: Mazuli manufactures Cortizo bifold doors at our factory in Leeds, and Cortizo is the system we recommend. We've kept every other brand's figures to what that brand states on its own website, and where a brand doesn't publish a figure, we say so rather than guess.

How do aluminium bifold door brands reach UK buyers?

Before comparing figures, it helps to know what a "brand" means in this market, because it changes who you buy from and who's responsible for the finished door.

System companies

Cortizo, Schüco, Smart Systems, AluK and Reynaers are system companies. They design and extrude the aluminium profiles, develop the hardware, and put the system through testing. They don't usually sell finished doors to homeowners. Instead, independent fabricators buy the profiles, then cut, machine, assemble and often glaze the doors to order. So when you buy a Cortizo or a Schüco bifold, the system comes from the brand, but the door is made by a fabricator.

That's what we do. We fabricate Cortizo bifolds in-house at our 25,000 sq ft factory in Leeds, from Cortizo profile, and supply them glazed or unglazed to trade and retail customers.

Brands that make their own doors

Origin works differently. It says all its products are designed and manufactured in-house, and it powder coats them itself. You're buying a finished door from the company that designed the system.

Why it matters

With a system brand, two doors on the same system can differ in build quality, glass, lead time and service, because they come from different fabricators. Ask who fabricates the door, as well as which system it is. With a brand that makes its own doors, the system and the factory are the same company. Either route can produce a good door. What counts is the specification and the people making it.

What should you compare between bifold systems?

• Maximum panel size and weight. Wider, taller panels mean fewer frames across the opening. Check the limits for the height you actually need.
• Maximum number of panels. This sets the widest opening you can fill with one set of doors.
• Whole-door U-value, with the glass stated. A figure quoted for the whole door (Uw) is what counts for the Building Regulations. A figure without the glass specification beside it can't be compared with anything.
• Weather test classes. Air permeability, water tightness and wind resistance, each tested to a European standard and reported as a class.
• Security testing. In the UK, the usual benchmark for doorsets is PAS 24. Some European brands report a burglar resistance class (RC) instead.
• Thresholds. Whether there's a low or flush option, and what it does to weather performance.
• Sightlines. The width of frame you see where panels meet. Brands measure this in different places, so compare section drawings rather than headline numbers.

On U-values, the standard in England is set by Approved Document L, Volume 1 (2021 edition incorporating 2023 amendments). For new or replacement doors in an existing home, Table 4.2 sets a maximum of 1.4 W/m²K, or a Doorset Energy Rating of Band C for doors with more than 60% of the internal face glazed. Our complete guide to aluminium bifold doors explains how that works for an extension.

Which aluminium bifold door system is best for UK homes?

For most UK homes and extensions, the system we recommend is Cortizo. We make Cortizo bifolds, so weigh our view with that in mind. The sections below give each brand's own published figures, Cortizo first, then the others in alphabetical order.

Cortizo Bifold: our pick for most UK homes

Cortizo is a system company, and its Bifold system is the one we fabricate in Leeds. Its published and tested figures:

• Panels up to 1,200mm wide, 3,000mm tall and 120kg, in 2 to 7 panels, for openings up to about 8,400mm.
• Whole-door U-value from 1.5 W/m²K double glazed (Ug 1.0) and 1.1 W/m²K triple glazed.
• Air permeability Class 4, water tightness Class 9A and wind resistance Class A3, tested at 1,200 Pa.
• The Cortizo bifold system has passed PAS 24 testing. Multi-point locking, shoot bolts on intermediate panels, anti-lift blocks and internal glazing beads are standard on our doors, with a 3-star anti-snap cylinder upgrade available.
• Standard (55mm), low (20mm) and low-with-rebate (40mm overall) thresholds.
• Cortizo's QUALICOAT-certified powder coating.

If you need 1.4 W/m²K for Part L, specify triple glazing, or use the Doorset Energy Rating route for a door more than 60% glazed.

AluK BSF70 HI and IconiK

AluK is a system company that publishes two bifold systems on its UK homeowner site.

• BSF70 HI: U-values of 1.4 W/m²K double glazed and 1.1 W/m²K triple glazed. Air tightness Class 4 (600 Pa), water tightness Class 9A (600 Pa) and wind load Class E (2,400 Pa). AluK states the system has PAS 24 security accreditation.
• IconiK: AluK's newer bifold, which it describes as having slimmer sightlines and larger glass panels, with a sightline of 87mm at the interlock on the IconiK Slim version. Each roller is rated to carry up to 130kg per panel. Shoot-bolt locking is optional.

AluK doesn't publish a maximum panel size or panel count on the pages we checked.

Origin OB-36, OB-49 and OB-72

Origin designs and manufactures its own doors and offers three bifold systems, named after their sightlines: 36mm, 49mm and 72mm.

• U-values: as low as 0.78 W/m²K on the OB-36, and as low as 1.1 W/m²K on the OB-49 and OB-72. Origin doesn't state the glass specification beside these figures on the pages we checked.
• Origin says all three systems meet PAS 24.
• Its FAQs give a maximum panel of 1,200mm wide by 3,000mm high, and openings from 1,400mm to 9,000mm wide and above.
• Thresholds: a weathered (rebated) threshold, which can be sunk so the upstand is 14mm, and a non-weathered threshold for a flush floor. Origin says its bifolds have withstood water test pressure of up to 600 Pa.

Origin doesn't publish air or wind classes on the pages we checked.

Reynaers ConceptFolding 77

Reynaers is a system company. Its UK site publishes these figures for ConceptFolding 77:

• Vents (panels) up to 1,200mm wide, 3,000mm tall and 120kg, in configurations of 2 to 8 vents.
• Uw 1.3 W/m²K. The glass specification isn't stated beside it.
• Air, water and wind classes of 4 / 9A / C3.
• Acoustic performance of Rw 45 dB.
• Low threshold and zero threshold options, and concealed drainage.

The product page lists a burglar-resistant option but doesn't give a security class.

Schüco AS FD 75 and AS FD 90.HI

Schüco is a system company. Its AS FD platform comes in two depths, AS FD 75 and AS FD 90.HI.

• Vent widths up to 1,500mm. Schüco's launch page gives maximum leaf sizes of 3.5m by 1.5m.
• Face widths of 90mm, with flush-fitted outer and vent frames.
• Burglar resistance class RC 2.
• Three threshold types, including a flat threshold, and an optional side-hung door for everyday access.

Schüco's UK pages for AS FD don't publish a U-value, a maximum panel count or weather test classes.

Smart Systems Visofold 1000

Smart Systems is a system company, and Visofold 1000 is its bifold door.

• Sashes up to 1,200mm wide and 2,500mm tall.
• 1.4 W/m²K using a 1.0 W/m²K centre pane, with foam insulation added to the profiles.
• A typical sightline of 122mm, frame depths of 70mm to 82mm, and glass units from 24mm to 38mm.
• A 30mm polyamide thermal break in the outer frame.
• The standard Visofold 1000 roller is PAS 24 approved.
• Two rebated outer frames, an integrated cill and a low threshold option.

Smart doesn't publish a maximum panel count or weather test classes on the product page.

How do the systems compare side by side?

This table uses each brand's published figures from the pages listed above. "Not published" means we couldn't find the figure on the brand's own pages, not that the system fails it. Sightlines are left out of the table because brands measure them in different places; they're in each brand's section above.

Reading the table fairly

• U-values aren't like for like. Some brands give a "from" or "as low as" figure without the glass, some give one figure for double and one for triple, and Smart's figure assumes foam-insulated profiles. Whole-door U-values also change with the size of the door. Ask each supplier for a calculated figure for your size and your glass.
• Wind classes use different letters and numbers. Cortizo's A3 was tested at 1,200 Pa and AluK gives 2,400 Pa for Class E. Reynaers publishes C3 without a pressure. Ask for the test pressure and the sample size before comparing.
• Security results differ in kind. PAS 24 is a UK test of the whole doorset. RC 2 is a European burglar resistance class. A PAS 24-approved roller is a tested component, not a tested doorset.
• Panel limits interact. Some brands also set a maximum panel weight, so a panel may not reach its maximum width and maximum height at the same time. Check the limits for the size you want.

Why do we recommend Cortizo?

We chose Cortizo to build our business on, so we're not a neutral party. These are the reasons we'd give a customer, and each one is a published figure you can check:

1. Tested security. The Cortizo bifold system has passed PAS 24 testing, and our doors come with multi-point locking, shoot bolts, anti-lift blocks and internal glazing beads as standard.
2. Tested weather performance. Air permeability Class 4, water tightness Class 9A and wind resistance Class A3.
3. Large panels and wide openings. Panels up to 1,200mm wide and 3,000mm tall, in up to 7 panels, for openings up to about 8,400mm.
4. A clear thermal route. From 1.5 W/m²K double glazed and 1.1 W/m²K triple glazed, with the glass stated, so you know what to specify for Part L.
5. A durable finish. Cortizo's QUALICOAT-certified powder coating, which we guarantee for 10 years against discolouration, flaking and UV fading.
6. A short, direct buying route. We make Cortizo bifolds to order in Leeds. Unglazed doors in our seven stock colours take 2–5 working days and glazed doors 6–10 working days, against a UK fabrication norm of 3–6 weeks. You get a delivery date when you order, and we deliver on our own fleet, with mainland UK delivery included.

None of that means the other systems are poor choices. Each of them has published strengths, and the right one depends on the project.

Which bifold system suits which project?

• Cortizo: our pick for most UK homes and extensions, where you want large panels, tested weather and security performance, and a short lead time from a UK fabricator.
• AluK: consider it if you want a system that publishes a Class E wind result, or the IconiK's 87mm interlock sightline.
• Origin: consider it if you want the system designer and door maker to be the same company, or the 36mm sightline of the OB-36.
• Reynaers: consider it if you need up to 8 panels, a zero threshold, or a published acoustic figure for a noisy site.
• Schüco: consider it for very wide leaves of up to 1,500mm, or where a project calls for an RC 2 burglar resistance class.
• Smart Systems: consider it if you want a published double-glazed figure of 1.4 W/m²K (with foam-insulated profiles) and a low threshold option.

Whichever system you choose, the door is only as good as its specification and its installation. Get the U-value for your size and glass in writing, check the test classes, and agree the threshold and floor levels before you order. Our guide to bifold doors for garden rooms covers the same questions for smaller buildings.

Mazuli Cortizo bifold doors

Mazuli is a fully accredited Cortizo manufacturer and one of the largest Cortizo-certified manufacturers in the UK. We fabricate Cortizo bifold doors in Leeds and supply them glazed or unglazed to installers, builders and homeowners across the UK mainland. We manufacture and deliver; we don't survey or install, so retail customers use their own builder or installer.

See specifications, colours and configurations on our aluminium bifold doors page, or request a quote. Installers and builders can open a trade account with no minimum order value.