How much space do the folded panels take up?
Each panel is about 7–8 cm thick. A stack of 5 panels takes roughly 40 cm beside the opening. Panels can fold inward or outward depending on your layout.
Folding Doors
Bi-fold systems that fold like an accordion and open up to 95% of the aperture
A folding (bi-fold) door is an aluminium system in which several panels are hinged together and slide along a single top track, folding into a compact stack to one or both sides of the opening. It completely removes the barrier between your home and the terrace, patio, or garden, turning a wall into a wide-open passage in seconds.
Our reference system is the Cortizo Bi-Fold range, built on a thermally broken aluminium profile with multi-contour weatherseals. It comes in two main variants — the standard Bi-Fold and the narrow-sightline Bi-Fold Slim — and is configured from 3 to 14 panels, with an optional "active" panel for everyday entry, inward or outward folding, and a choice of thresholds (flush barrier-free or framed). Frames and sashes are available in the full RAL palette, anodised, and wood-effect finishes.
Cheat Sheet by Series
Popular folding systems and their price positioning relative to Cortizo
| Manufacturer | Popular series for folding systems | Price positioning (relative to Cortizo) |
|---|---|---|
| Cortizo | Bi-Fold / Bi-Fold Slim | Baseline |
| Strugal | S74 RPT | About the same level / slightly cheaper |
| Exlabesa | S70 FOLD | Slightly cheaper |
| Alumil | Supreme SF85 | Same level (more minimalist design) |
| Airclos | S220 RPT / S70 series | More expensive (specialise strictly in folding systems) |
| Reynaers | CF 77 (Concept Folding) | 30–40% more expensive |
| Schüco | AS FD 75 / AS FD 90 | 40–60% more expensive |
| Solarlux | Ecoline / Highline | Top premium (several times more expensive) |
What to Consider When Choosing an Alternative
The threshold is the detail that makes or breaks a folding system
The threshold is critical for accordion-style folding doors. When the system is installed outdoors — opening onto a terrace — Cortizo and its competitors offer two threshold types: a flush threshold (low, barrier-free) and a framed threshold (with a raised lip).
Keep in mind that a flush threshold almost never provides 100% watertightness against heavy, slanting rain. If you need maximum leak protection in harsh conditions, always choose a classic framed threshold — regardless of the brand.
Advantages of Folding Doors
Why customers choose bi-fold systems for terraces and verandas
- Maximum opening — panels fold to the side, freeing up to 95% of the aperture.
- Flexible configuration — from 3 to 14 panels, with an "active" panel for everyday entry.
- Warm and airtight — thermal break and multi-contour seals for year-round use.
- Barrier-free — recessed threshold option for an unobstructed passage.
FAQ
Frequently Asked Questions About Folding Doors
Are folding doors warm enough for year-round use?
Yes. Modern bi-fold systems use a profile with a thermal break and multi-contour weatherseals, achieving thermal insulation comparable to standard windows (Uw down to 1.1 W/m²K).
What is the maximum opening width?
Modular systems connect up to 14 panels (7 on each side). With panels up to 1.2 m wide, the structure can span openings over 16 metres.
Can a folding door be used as the main entrance?
Yes, with a configuration that includes an "active" panel — it has a lever handle set and a cylinder lock, so it works as a secure everyday door.
Ready to spec your windows?
Use the 3D configurator to size up your windows and see a fair market price. Or compare the leading PVC and aluminium brands side by side.