An aluminum bifold patio door is a thermally broken aluminum door whose 2 to 8 hinged leaves fold and stack to the side. The four European systems I source fold inward or outward and take leaves up to 3 ft 11 in wide and 9 ft 10 in tall, and the four with a published triple-glazed value run from U-0.16 to U-0.26. This page covers the product itself; pricing has its own guide, linked in the last section.
A Reynaers ConceptFolding 68 bifold, provider image.
What Are Aluminum Bifold Patio Doors?
A bifold patio door is a set of glass leaves hinged to one another that fold accordion-style and stack at the jamb, so the clear opening depends on where the stack lands rather than on a fixed panel, unlike a typical two-panel slider without a pocket, which opens about half its width. I read the clear opening from the layout drawing. You will also see them called folding glass doors, aluminum folding patio doors or accordion glass doors; it is the same product.
Which Aluminum Bifold Systems Do I Source?
I source four aluminum bifold systems, listed below with the values published for each. They are system-provider platforms; I source finished units built on them.
| System | Frame depth | Panels | Largest leaf (W x H) | Weight per leaf | Published whole-door value in US units | Thresholds |
|---|---|---|---|---|---|---|
| Reynaers ConceptFolding 68 | 2.68 in | 2 to 7 | 3 ft 3 in x 8 ft 10 in | not published | U-0.19 (Uw 1.10); U-0.29 (Uw 1.64) double | not listed (2 or 3 seals) |
| Reynaers ConceptFolding 77 | 3-1/16 in | 2 to 8 | 3 ft 11 in x 9 ft 10 in | 265 lbs (120 kg) | U-0.26 (triple, Functional variant) | 4 options |
| Aluprof MB-86 Fold Line HD | 3.39 in | 2 to 8 | height to 9 ft 10 in, width not published | 265 lbs (120 kg) | U-0.18 (Uw 1.00, SI variant); U-0.19 (Uw 1.10, standard triple) | low-profile or flush |
| Aliplast Panorama | 2.93 in | 2 to 8 (2+1 layouts) | height to 8.5 ft, width not published | 220 lbs (100 kg) | U-0.16 (Uw 0.89), i+ tier | flat with brush seal, or sealed full perimeter |
Leaf weight and width limits decide the layout, and I confirm them on the shop drawing.
How Many Panels and How Wide Can a Bifold Patio Door Be?
Aluminum bifolds from these systems fold 2 to 8 leaves (the ConceptFolding 77 brochure lists 2 to 8 leaves at 120 kg each), and the ConceptFolding 68 lists openings up to 19 ft 8 in (6,000 mm) with leaves up to 3 ft 3 in wide. The Panorama also lists 2+1 layouts and mullion-free corner solutions, up to 8 panels in total.
For stock sizes and rough openings, patio door sizes has the grid. For the span question against sliders, see choosing between folding and sliding. I do not quote a typical maximum span beyond the 19 ft 8 in figure, because the other limits depend on leaf count and weight.
Do Bifold Patio Doors Fold In or Out?
Both directions are available, and the plan decides which one you want. These are the options each system lists:
- Fold direction. All four systems list inward or outward folding; the ConceptFolding 77 describes it as both inward and outward opening.
- Traffic door. The ConceptFolding 68 and the Fold Line HD list a traffic-door option, a leaf you walk through without opening the whole stack.
- Entrance leaf. On the ConceptFolding 77 the first leaf can be a standalone entrance door, without affecting the folding operation.
Where the stacked leaves land (interior furniture or the deck) and how the weather side is detailed are drawing decisions, so I settle them with you before production.
What Thresholds Can an Aluminum Bifold Door Have?
The ConceptFolding 77 lists four threshold options: High Performance, Double Weather Seal, Low (3/4 in rise) and Flat Bottom for barrier-free access. The other systems list these:
- Fold Line HD: low-profile or flush.
- Panorama: flat with a brush seal for a near-flush floor transition, or a sealed full-perimeter frame.
- ConceptFolding 68: not listed in my catalog.
Glass in the leaves of a bifold door is a hazardous location under IRC R308.4.1, so the glazing is safety glass; I confirm your adopted code and local amendments. Floor drainage and sill detail belong to your architect and installer, and I confirm the sill on the shop drawing.
What U-Factor Do Aluminum Bifold Patio Doors Reach?
The four systems publish triple-glazed values from U-0.16 (Panorama i+) to U-0.26 (ConceptFolding 77, Functional variant), and the ConceptFolding 68 lists U-0.29 double glazed. I convert the provider's metric Uw by multiplying by 0.17611, so these are not NFRC ratings, and I confirm the figure for the specific assembly.
The frames are thermally broken: the Panorama is a 3-chamber profile with polyamide thermal breaks, and the Fold Line HD is built on the thermal MB-86 platform. How the thermal break works explains the mechanism, and triple pane patio doors covers glass weight and glazing limits.
Folding doors on the deck elevation of the Black Rock Residence project, photographed during construction. The project also has a site video of its folding doors opening.
Where Do Aluminum Bifolds Fit Against Sliders?
Choose a bifold when you want the whole wall open, and a slider when you want bigger glass panels and single-handle operation. The full comparison is in folding vs sliding; aluminum sliders are in aluminum sliding patio doors, and slimmer frames in minimal-frame sliders.
How Do I Order Aluminum Bifold Patio Doors?
Ordering takes four steps, and the panel layout is fixed at the second one:
- Send me the drawings or the opening in inches, and I return a budget the same or next working day.
- I send shop drawings 2 to 3 working days after your review, where panel count, fold direction, stack side and threshold are fixed.
- Lead time is confirmed per order.
- Your local team installs the doors; the 10 installation steps for a bifold patio door show what that job involves.
If you are asking what a bifold costs, the bifold door price guide by opening size has it. To start your own opening, use the estimator or send me the size.
FAQ
How many panels can an aluminum bifold door have? The ConceptFolding 68 lists 2 to 7 panels, and the ConceptFolding 77, Fold Line HD and Panorama list 2 to 8.
Can aluminum folding patio doors open outward? Yes. All four systems list inward or outward folding.
Are aluminum bifold doors energy efficient? Published triple-glazed values run from U-0.16 to U-0.26, against U-0.29 double glazed on the ConceptFolding 68. They are provider metric values converted to US units, not NFRC ratings, and I confirm them per assembly.
Can one leaf of a bifold be a walk-through door? Yes. The ConceptFolding 77 lists its first leaf as an entrance door, and the ConceptFolding 68 and Fold Line HD list a traffic-door option.
Have an opening in mind? Run it through the estimator or send me the size. See also more door guides.
Kai, your window guy!