Bifold Doors
External Bifold Doors
About External Bifold Doors
External bifold doors are aluminium folding doors set into an outside wall, usually at the back of the house, that fold back to one side so most of the wall opens onto the garden, patio, terrace or balcony. They are also called exterior bifold doors or bifold patio doors. We make every set to measure on Schüco and Cortizo systems, and supply and fit them across London, Berkshire, Surrey, Kent and Essex, or supply them only to trade buyers and homeowners with their own installer.
An outside set has to keep out wind and driving rain as well as open up, so three choices matter more than on an internal door. The threshold: a weathered threshold gives the most protection where the doors face the weather with no overhang, while a low or flush threshold gives a near-level step onto the patio but needs drainage designed into the floor outside. The Schüco AS FD 75/90.HI, for example, comes with 71mm, 15mm or an ultra-low 4mm threshold. The opening direction: outward-opening sets stack the folded panels outside, keeping the room clear; inward-opening sets stack inside, which suits a narrow balcony or a terrace where panels would be in the way. And the frame: thermally broken aluminium with sealed drainage, so the doors stay warm and dry in British weather.
Because they form part of the outside wall, external bifold doors have to meet Building Regulations. In England, new and replacement external doors in existing homes and extensions need a U-value of 1.4 W/m²K or better under Approved Document L. Our systems are thermally broken, double glazed as standard with triple glazing available, and reach 1.0 W/m²K on the Schüco AS FD 75/90.HI and from 0.8 W/m²K on the Cortizo Bifold Plus. The glass is toughened safety glass, locking is multi-point, and the systems are tested to PAS 24.
Sets run from 2 to 7 panels and spans past 6 metres. As a rule of thumb, 2 panels suit openings up to about 1.8m, 3 panels up to 2.4m, 4 panels up to 3.2m and 5 panels up to 4.0m, and a traffic door lets one leaf work as the everyday back door. Guide prices run from around £2,400 for a 2-panel set to £9,600 for a large 7-panel run, supplied and fitted including VAT. For a corner opening with no post, see Schüco cornerless bifold doors; for shopfronts, restaurants and office terraces, see commercial bifold doors.
How much do bifold doors cost? Our bifold door price guide sets out supplied-and-fitted guide prices for every panel count, from 2 to 7 panels.
Last reviewed 2 November 2026
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Key features
- Fold back to one side to open most of an outside wall onto the garden
- Weathered, low or flush thresholds, down to 4mm on the Schüco AS FD 75/90.HI
- Outward opening to keep the room clear, or inward opening for balconies
- Thermally broken frames and sealed drainage for British weather
- Specified to meet Part L: 1.4 W/m²K or better for replacement doors in England
- Multi-point locking and toughened safety glass; systems tested to PAS 24
- Optional traffic door for everyday use as the back door
- 2 to 7 panels, with spans past 6 metres
- Double glazed as standard; triple glazing and integrated blinds available
- Anthracite grey, black, white or dual-colour finishes
- Supplied and fitted, or supply only for trade
Specifications
Frequently asked questions
Common questions about External Bifold Doors.
What are external bifold doors?
Folding glazed doors fitted in an outside wall, usually at the back of a house, that fold back to one side to open most of the wall onto a garden, patio, terrace or balcony. They are also called exterior bifold doors or bifold patio doors. BDF Architectural makes them to measure in aluminium on Schüco and Cortizo systems.
Should external bifold doors open inwards or outwards?
Outward opening is the usual choice for a garden or patio, because the folded panels stack outside and leave the room clear. Inward opening suits a narrow balcony or terrace where outward-folding panels would be in the way. Both are available on our systems.
Should I choose a weathered or a flush threshold?
A weathered threshold gives the most protection where the doors face the weather with no overhang. A low or flush threshold gives a near-level step to the patio but needs drainage designed into the floor outside. The Schüco AS FD 75/90.HI offers 71mm, 15mm and 4mm thresholds.
Do external bifold doors need Building Regulations approval?
Yes. In England, replacing an external door that is more than half glazed, or forming a new opening, is building work that must meet Building Regulations, including a U-value of 1.4 W/m²K or better under Approved Document L and safety glass under Part K. It is certified through a competent person scheme or a building control application.
How much do external bifold doors cost?
As a guide, from around £2,400 for a 2-panel set to £9,600 for a large 7-panel run, supplied and fitted including VAT. The price depends on the size, number of panels, system, glazing and finish; our bifold door cost guide breaks it down by panel count.
Can I buy external bifold doors supply only?
Yes. We make the doors to your sizes and supply them ready for your own installer to fit, with delivery UK-wide at extra cost or collection from West Drayton. Trade buyers can send a schedule for pricing.
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