Not every back room in Uckfield has space for a wide slider. A lot of semis and terraces from the 1960s and 70s have a back wall around 1.5 metres wide where the old door sits, with a kitchen window beside it. That is French door territory.
French doors
Two doors that both open outward, hinged at the sides, meeting in the middle with no post when open. They give you the full width of the opening on a summer evening, which a slider of the same width cannot do because one pane always stays behind the other.
They come in white or coloured uPVC, which is the less expensive route, or in aluminium with slimmer frames. Aluminium French doors pair well with aluminium windows in the same room.
Patio doors in the old sense
The sliding patio door of the 1970s and 80s, usually in uPVC or old aluminium, is what most people are replacing. Today the like-for-like answer is a two-pane aluminium slider. See sliding doors.
When French doors are the better choice
The opening is under about 1.8 metres wide.
You want the whole gap open, not just half of it.
The doors open onto a side passage or small patio where a sliding panel would stack against a wall.
You want a uPVC door to match uPVC windows that are staying.
When they are not
Outward-opening doors catch the wind. On an exposed site, such as the higher ground towards Ashdown Forest around Nutley, you need good stays or the doors will swing back against the wall. A slider has no such issue. Inward-opening French doors are possible but take floor space from a small room.
A typical job
Illustrative example of a typical job
White uPVC French doors and a kitchen window, 1970s semi in Uckfield
The house: A brick 1970s semi-detached house in Uckfield with an old sliding patio door at the back and a small kitchen window beside it.
The spec: A pair of white uPVC French doors, about 1500 mm wide, in the existing opening, plus one small white uPVC flush casement over the sink.
Typically £3,050 to £4,400, supplied and fitted, including VAT.
The cheapest way to swap a tired patio door for something that opens fully on a warm day. No widening, no steel, one day on site in most cases.