Alumil bifolding doors take the familiar folding door concept and move it into more technical, more architectural territory. These systems are engineered for very slim sightlines, large panel sizes and smooth, predictable operation over many years. They are used internationally in homes, hotels, high-rise buildings and premium commercial schemes where safety, reliability and appearance all matter.
For the UK, Alumil’s bifolding range offers something beyond the typical trade systems. You get advanced thermal performance where it is required, non-thermal options where it is not, a shared minimal design language, and hardware designed for effortless, confident use. Every detail is considered – from the proportions of the profiles to the feel of the handles and the way the doors stack and run on their tracks.
Alumil MF65 Bifold Door
SMARTIA MF65 is a thermally insulated folding door system and the slimmest bifold door in the UK, with an 88mm sightline where sashes meet. Built around a 65mm sash depth, it is well suited to both new build and replacement projects, including upgrading older aluminium or PVCu doors to a more minimal, glass-led aesthetic.
Panels can be specified up to 1.3m wide or 3.0m high, supported by bottom-running heavy-duty roller gear that runs on stainless steel tracks for smooth, consistent movement. Quadruple latches on the intermediate leaves, multi-point locking on the main door and an anti-lift mechanism contribute to strong security performance, while the thermal design allows U-values down to around 1.1–1.3 W/m²K with appropriate glazing.
Because of its slim depth and flexible typologies, MF65 can also be configured as ultra-slim single and double doors, giving you matching hinged doors with the same minimal sightlines. It is a good option where you want a very slender folding door system with proven insulation and day-to-day reliability.
Alumil SF85 Bifold Door
The Alumil SF85 is a high-performance, thermally insulated bifold designed for contemporary extensions and larger openings. It combines very slim mullions – around 120mm where the panels meet – with panel sizes up to approximately 1.2m wide and 3.0m high. This allows wide spans to be achieved with fewer panels, giving more glass, fewer verticals and better views out, even when the doors are closed.
Internally, deep polyamide thermal breaks and insulated chambers work with high-spec double or triple glazing to achieve low U-values, typically around 1.3 W/m²K with double glazing and down towards 1.1 W/m²K with triple glazing. Dual seals around the frame and sashes help with weather protection and acoustic comfort, while dedicated heavy-duty hardware ensures the doors roll and fold smoothly.
Security is enhanced by a multi-point locking system with four-way shoot bolts on the main door leaf, tested to the latest standards such as PAS 24 when specified correctly. Matching single and French doors can be created from the same profile suite, giving a consistent look across rear elevations and side doors.
SMARTIA MF6500 Internal Folding Door
SMARTIA MF6500 is a non-insulated folding door system based on the same minimal design language as MF65, but intended for internal or non-thermal applications. It retains the slim 88mm sash-to-sash sightline and panel sizes up to 1.3m wide and 3.0m high, making it suitable for large internal partitions and room dividers.
Although it is non-thermal, MF6500 still offers strong performance in terms of air permeability, watertightness and wind resistance, which is useful in sheltered external areas, covered terraces or between conditioned and semi-conditioned spaces. Bottom-slide operation, heavy-duty roller hinges and robust hardware give a reassuringly solid feel in everyday use.
Typical applications include open-plan living dividers, linking kitchens with garden rooms, separating offices from meeting spaces or creating flexible zones in commercial interiors. Low thresholds, smooth floor interfaces and the option for pockets or wide openings mean MF6500 can replace the need for exterior-grade doors where insulation is not required, without sacrificing quality or appearance.
Why Choose Alumil Bifolding Doors?
Alumil bifolds are sophisticated, carefully engineered systems rather than lightly adapted patio doors. They are designed to accept modern glass specifications, offer meaningful thermal performance where required, and provide smooth, predictable operation with slim, controlled sightlines. For many models, the design avoids the complexity of bonded glass arrangements, using beaded construction and accessible gaskets that simplify glazing replacement and maintenance.
The same engineering principles that see Alumil products used in demanding climates and prominent international projects are applied to these folding doors. That means high static performance, well-resolved drainage, thoughtful threshold options and hardware that is matched to the size and weight of the panels. For UK projects, this translates into doors that not only look minimal and contemporary, but feel well balanced, secure and durable in everyday use.
For Manufacturers
For manufacturers, the Alumil bifold range offers a route into higher-specification folding doors without stepping outside practical fabrication processes. SF85 provides a flagship thermally broken system for larger openings and higher-end projects, MF65 delivers ultra-slim insulated bifolds (and matching single/double doors) with a compact 65mm depth, and MF6500 gives a non-thermal option for internal and sheltered applications – all with a coherent visual language.
Shared design thinking, consistent hardware families and well-documented typologies help with production planning and stock management. Beaded glazing and sensible adjustment options support efficient assembly and servicing, while certified performance and clear technical data help with specification conversations. For factories looking to differentiate from standard trade systems and reduce direct price comparisons, Alumil bifolds add a distinctive, design-led product set to the portfolio.
For Installers and Showrooms
For installers and showrooms, Alumil bifolding doors provide a clear way to stand out from the many generic systems on the market. The slim meeting sections, modern profiles and well-finished thresholds make an immediate impression in a display environment, and the smooth movement of the panels reinforces that sense of quality when customers try the doors for themselves.
On site, features such as built-in adjustment, bottom-running gear on MF ranges and installer-friendly frame design help reduce fitting time and fine-tuning. The range covers insulated and non-insulated doors, large spans, low thresholds and internal dividers, so you can answer a wide variety of briefs without constantly switching between unrelated systems. For installers who want to build a reputation around design and reliability rather than price alone, Alumil bifolds are a strong addition to the offering.
For Homeowners
For homeowners, the appeal of Alumil bifolding doors is straightforward: more glass, slimmer frames, and doors that feel solid and easy to use. Systems like SF85 and MF65 bring high levels of thermal insulation and weather protection, helping keep homes comfortable year-round while still opening up generously to the garden or terrace when required. The ability to use fewer, wider panels in some configurations reduces the number of vertical mullions, improving views and natural light.
Hardware and locking have been designed with security in mind, including multi-point locks, multi-latch intermediate panels and anti-lift measures. Threshold options and careful detailing at floor level help avoid trip points and ease access. For internal spaces, MF6500 offers the same minimal look without paying for insulation that is not needed, allowing flexible layouts and open-plan living without committing to fixed walls. Overall, Alumil bifolding doors provide a more refined and capable alternative to typical folding doors.
For Architects and Designers
Architects benefit from bifold systems that combine controlled, minimal sightlines with a wide range of panel sizes and configurations. SF85, MF65 and MF6500 support tall doors, wide leaves and larger runs with options for odd or even panel counts, traffic doors, low thresholds and varied stacking arrangements. This flexibility allows bifolds to be used in more situations, from domestic kitchen extensions to hospitality, leisure and mixed-use projects.
The systems have been developed with contemporary architecture in mind: slim mullions, clean profiles, consistent gasket lines and hardware that does not dominate the appearance. Thermal and structural performance data are available to support Part L and wind-loading calculations on external applications, while non-thermal variants extend the same visual language indoors. For schemes where the folding door needs to look and feel like a considered part of the architecture rather than an afterthought, the Alumil bifold family offers a credible, specification-friendly solution.
Contact us for further information about ALUMIL bifolding doors.
Use our contact form to ask a question, get prices or find out where to view or buy the ALUMIL SF85 bifolding door.
