Patio door is a category, not a type. It covers any glazed door leading to a garden, patio or balcony, and the types inside it differ by how they open. French doors swing on hinges. Sliding doors run on a track. Bifolds fold back in panels. The right choice comes down to your opening width and the space you can give up.
Every French door is a patio door. Not every patio door is French in style.
Bifolds give the widest clear opening. Sliding doors give away the least floor space.
Hinged doors need swing room, indoors or out, and that room is not free.
Narrow opening? Hinged. Wide opening with no space to spare? Sliding.
We make hinged, sliding and tilt-and-turn doors. We do not make bifolds, and this guide says when a bifold is the better answer.
The terminology causes more confusion than the products do, so start here.
So a shop selling you "patio doors" has told you nothing about how the door opens. Ask which mechanism, and whether it comes as a single or a double.
One more distinction worth knowing. A single patio door is one hinged glazed door, suited to narrower openings. A French door is a pair, and a pair without a central post gives you the full width of the opening when both leaves stand open. On ours the main leaf works from the handle, and the second leaf releases on bolts at the top and bottom of the frame.
Clear opening is the figure that decides most of these projects. It means the gap you can actually walk through, and it varies enormously between mechanisms.
Read that clear opening row carefully, because it catches people out. Two 838mm French leaves do not give you 1676mm of usable gap, and a two-panel slider gives you roughly half its total width whatever the brochure photograph suggests.
A hinged door swings on its hinges rather than travelling along a track, and that buys you two things: a wide clear opening for the size of the door, and a traditional look that sits comfortably on most British houses.
Hinged doors also seal well. A multi-point lock pulls the leaf into a compression gasket around its whole perimeter, and that is a simpler job than sealing a panel that has to slide. If draughts and weather-tightness sit near the top of your list, hinged is the straightforward answer.
The cost is space. An outward-opening pair needs its swing arc kept clear on the patio, which rules out furniture, planters and anything else you wanted there. An inward-opening pair takes the space from your living room instead. Measure the arc before you decide, because on paper it looks smaller than it feels.
Choose a single patio door where the opening is too narrow for a pair. It still floods the room with light, and it gives you the full leaf width to walk through.
Choose French doors where you want the whole opening usable and you have the swing space. The glazing bar pattern is a style decision rather than a functional one: bars for a period look, a plainer face for a modern line.
A sliding door gives up nothing to swing arcs. Turn the handle and the door lifts slightly onto its rail, then slides sideways. Open or shut, it occupies the same footprint.
That lifting action matters more than it sounds. Older inline sliders dragged along their track, which wore the rollers and let weather through. A lift-and-slide mechanism carries the leaf on rollers while it moves and drops it onto its seals when it closes, so the sealing surface is not the running surface.
Sliding doors suit three situations well. Small rooms where a swing arc would eat the furniture layout. Patios and balconies too narrow for an outward-opening pair. And wide openings where you want large panes of uninterrupted glass rather than a row of frames.
The trade-off is clear opening. On a two-panel slider, one panel slides behind the other, so you get roughly half the total width. A three-panel arrangement improves on that. If the widest possible gap is the goal, sliding is not the mechanism for it.
We do not make bifolds, so take this as a straight comparison rather than a sales case.
Bifolds fold back on themselves in panels, concertina-style, and they open up more of the aperture than any other mechanism. On a wide rear extension where you want the wall to disappear in summer, nothing else matches them.
Three things to weigh against that.
They stack somewhere. Folded panels need depth, either inside the room or outside against the wall. That space has to be clear and it has to stay clear.
More frame when closed. Each panel carries its own frame, so a five-panel bifold shows you five vertical bars across the view for the nine months a year it stays shut. A large sliding pane or a French pair shows fewer.
More joints to seal. Every panel meets its neighbour, and every meeting point is a seal that has to work and keep working. Bifolds handle this well when specified and installed properly. They have more of it to get right.
Choose a bifold if your opening is wide, you want to open nearly all of it, you have stacking space, and the summer view with the doors open matters more to you than the winter view with them closed.
Choose a sliding door instead if the opening is wide but you look through the glass more often than you walk through it, or if you want fewer frames and fewer seals to maintain. A slider costs less than a bifold across most of the market and does more of the same job than people assume.
British suppliers rarely stock these, which is why the comparison articles skip them. They come from the Scandinavian tradition and they solve a problem the other four types cannot.
The handle has two positions. Turn it one way and the door swings open on its hinges as normal. Turn it the other and the top of the door tilts inward while the bottom stays sealed. You get controlled ventilation with the door still fastened.
That matters on a balcony or a first-floor room where you want air without an open door: no swing arc, no security worry, no rain coming in horizontally. For flats and upper floors this is usually the right answer, and it almost never appears on a UK shortlist because almost nobody offers it.
Work through the decision in this order. The opening decides more than the aesthetics do.
Opening under about 900mm. A single patio door. Nothing else fits.
Opening 900mm to 1800mm, with swing space. French doors. Best clear opening for the width, best sealing, traditional look.
Opening 900mm to 1800mm, no swing space. A sliding patio door, or a tilt-and-turn on a balcony.
Opening 1800mm to 3000mm. Sliding, if the view and the maintenance matter most. Bifold, if opening the whole wall matters most.
Opening over 3000mm. Bifold or a multi-panel slider. Get someone to survey it. At that width the lintel and the structural support drive the specification more than the door does.
First floor or balcony, any width. Tilt-and-turn.
Two constraints that override all of the above. If you get strong prevailing wind and rain on that elevation, favour hinged and lift-and-slide over anything with more seal joints. And if the door faces a walkway or a shared garden, an outward-opening leaf across a public route creates a problem you do not want.
