French Door Installation

An in-swing French door opens into the room. It is the North American default, and its great advantage is weather: the door closes against a stop on the exterior side, so wind-driven rain pushes the panel harder into its weatherstripping rather than away from it. Its cost is floor space — a pair of in-swing panels sweeps a large arc into the room, and that arc has to stay clear of furniture, a rug edge, a floor register, a radiator and any door swinging the other way.

An out-swing French door opens onto the patio or deck and gives the whole interior arc back. It is the right call in a room where the furniture plan cannot absorb the swing, and it is common on three-season rooms and on shore houses. The tradeoffs are real: the seal now works against the wind rather than with it, so the threshold and the corner seals have to be right and the weatherstripping is doing harder work; the hinges are on the exterior, so they need to be non-removable-pin or security-studded; and the patio side needs enough flat, clear space for the panels to swing without hitting a railing, a grill or a step-down.

Nor'easters are the reason this is not a stylistic choice in New Jersey. Wind-driven rain here arrives horizontally against east and northeast elevations for hours at a time. On an exposed elevation with no roof over the opening, in-swing is the safer geometry. On a covered porch or a protected elevation, out-swing is perfectly serviceable and often the better use of the room. We look at the elevation, the overhang and the interior furniture plan together, because picking swing off a floor plan without standing in the room is how people end up with a door they resent.

On almost every French door one panel is the active leaf — the one with the handle that you use every day — and the other is the passive or inactive leaf, held shut by flush bolts or a multipoint mechanism at head and sill and opened only when you want the full width. Which side is active is a decision, and it is worth making deliberately: active on the side nearest the traffic path from the kitchen, or nearest the steps down to the patio, not simply whichever side the supplier defaults to. Handing is set at the factory and is expensive to change later.

The astragal is the vertical member on the meeting edge that the active panel latches into. There are two schools. A fixed astragal is attached to the passive panel and gives you a solid, well-sealed strike for the active door — the better weather detail, and the reason it is the common choice on exterior doors. A removable astragal comes out with the doors open so the full opening is genuinely unobstructed, which matters exactly once, on the day you carry a sofa through it, and slightly compromises the seal every other day of the year.

The passive panel's bolts are the part people never think about and the part that decides how the door ages. Flush bolts that drop into a strike at the head and into a floor socket at the sill hold the panel rigid; skimpy bolts or a sloppy floor socket let the passive leaf move a few millimetres under wind load, and the active door starts catching on the astragal. On better doors the passive panel is secured by its own multipoint mechanism rather than by two bolts, which distributes that load along the full height.

A single deadbolt at the middle of a tall door panel clamps the door at one point and leaves the top and bottom corners free to bow away from the weatherstripping under wind pressure. On a window that would be a draft. On a seven-foot door panel it is a whistling gap in a February gale and a wet threshold in a nor'easter. Multipoint locking solves it mechanically: lifting the handle drives bolts or hooks into the frame at several points along the height, drawing the panel evenly against its seals top to bottom, and turning the key throws the deadbolt.

That even compression is doing three jobs at once. It is the weather seal, so the door actually performs to the air- and water-infiltration numbers on its label. It is the security, since a multipoint engages the frame at points a pry bar can't all reach at once. And it is what keeps a tall panel straight over time, because a door held evenly along its height is a door that doesn't take a set.

The corollary is that a multipoint system depends on the frame being installed dead square and staying that way. A door hung out of square will still latch for a while — the mechanism has tolerance — but the bolts will engage progressively harder until one day the handle won't lift. That is not a lock failure; it is an install failure that took two years to appear. It is also why we shim and check French door frames more obsessively than any other opening we hang, and why sagging on an existing French door is usually a frame or hinge problem rather than a lock problem.

Water finds French doors at the bottom corners of the panels, where the vertical weatherstripping, the sill's horizontal seal, and the astragal or the meeting stile all converge. Three sealing planes meeting at a point is the hardest detail in the door, and it is where nearly every leak we get called to originates.

The sill itself needs to be a drainage component, not just a piece of trim: a sloped, thermally broken threshold with weep channels that carry water that gets past the first seal back to the outside, and end dams so it can't run sideways into the framing. Under that, a proper sill pan — a self-adhered or formed pan with a back dam and sealed corners — is what turns an eventual leak into a nuisance instead of a rotted rim joist. Skipping the pan is invisible on install day and expensive five winters later, and it is the single most common thing we find missing when we tear out a failed French door.

Height matters too. Where the door opens onto a deck or patio at nearly the same level as the interior floor, the threshold has very little vertical distance to work with and water management gets much harder — that is where a taller commercial-style threshold or a step-down on the exterior earns its place. On shore properties in flood hazard areas the sill height is not a preference at all; it is set by base flood elevation and local freeboard requirements, and the whole threshold detail follows from that number.

Interior French doors have none of these problems and a different one: they are usually hung in an existing opening that isn't square, in a wall that isn't plumb, in a house that has moved. Getting a hinged pair to meet cleanly down a seven-foot vertical line in a 1920s Colonial is a shimming exercise, and the doors are frequently ordered undersized on purpose so there's material to work with.

This is the practical objection to French doors and it has good answers now. A hinged pair has no track for a sliding screen to live in, so the options are retractable, hinged, or none.

Retractable screens are the common solution: the mesh lives rolled in a slim cassette at one or both jambs and pulls across the opening on a low track when you want it, disappearing entirely when you don't. Single-cassette versions cover a single active panel; double versions meet in the middle to screen the full opening. They keep the look of the door intact, which is usually why somebody chose French doors in the first place. They are hardware, so they want the opening square and the track kept clean, and the mesh should not be let go to snap back.

Hinged screen doors — essentially a light screen door hung in front of each panel — are the durable, unglamorous option. They handle a dog leaning on them far better than a retractable does, and they suit a back door off a kitchen where function beats appearance. Mesh choice matters more here than on a window: pet-resistant polyester on any door a dog uses, tight-weave no-see-um mesh near marsh or water, enhanced-visibility mesh where the view is the point. We re-mesh both types at the Garfield shop.

A French door and a sliding door of the same nominal size generally drop into a similar rough opening, and the header above them carries a similar load. So the structural conversation is largely the same and the swap in either direction is usually feasible without reframing. What changes is everything below and around the opening.

Swing space is the obvious one: the French door needs a clear arc on one side or the other, the slider needs none. The threshold detail differs, because a slider seals against a fixed track and a hinged pair seals against compression hardware. The locking is different in kind, not degree. And the clear opening you get is different: both panels of a French door open to give you nearly the full width, where a slider's operating panel gives you roughly half.

Which one belongs on your opening depends on the room, the patio, the elevation and the look you're after — and that comparison has its own guide rather than a paragraph here. What we'll say from the install side is that we hang and repair both, so the recommendation isn't steered by what we'd rather install.