Doors · Service

French door installation, and where the leaves will swing

Two leaves, one of which barely moves. Which one is active, which way the pair opens, and how much floor you give up are the decisions that make a French door pleasant to live with — or a daily irritation.

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In short

What is french door installation?

French door installation fits a pair of hinged, glazed doors into one opening. Day to day, one leaf is the active door you use; the other is held shut by flush bolts into the head and floor and opens only when you need the full width. The join between them is closed by an astragal. Getting the handing, the swing direction and the floor clearance right at the quoting stage is what separates a pair you enjoy from one you stop opening.

Triggers

Signs you need french door installation

You want the full opening usable at once — moving furniture, entertaining, carrying things through — which a slider with a fixed panel cannot give you
You are replacing a tired slider and the room has floor space to spare on one side
You want to divide two interior rooms while keeping the light and the sightline — a study, a dining room, a bedroom off a landing
A single door is too narrow for the traffic through it, and a single wide leaf would be too heavy to swing comfortably
You want a door pair that can be locked open on a fine day, which swinging leaves do and sliders do not

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The job

How french door installation actually works

Handing and swing decided on the floor, not on paper

Handing is which leaf is active and which side its hinges are on. Swing is whether the pair opens into the room or out of it. Both are set at the point of order and cannot be changed afterwards on a pre-hung exterior pair.

Watch for: A handing chosen by whoever fills the order form. Stand in the doorway, walk through it, and decide which side you naturally reach for. Then mark the swing arc on the floor with tape and leave it there for a day.
In-swing versus out-swing, on an exterior pair

Out-swing sheds weather better and gives you the floor space back, which is why it is common in wet and windy locations. In-swing keeps the hinges inside where they cannot be attacked and is the default in most of the US.

Watch for: Out-swing exterior doors with ordinary hinge pins on the outside. If you go out-swing, the hinges must be non-removable-pin or have security studs, or the whole door can be lifted off.
The astragal and the locking arrangement

The astragal is the vertical closer strip on the inactive leaf that the active door shuts against. On an exterior pair, that inactive leaf is held by flush bolts top and bottom, and the active leaf locks into the astragal. Multipoint locking, which throws bolts at several heights, is the stronger arrangement on tall glazed pairs.

Watch for: Flush bolts that engage into nothing but the threshold surface. The bottom bolt should drop into a proper socket, and the top into the head jamb — otherwise the inactive leaf flexes and the pair rattles.
Setting the unit, and the reveal down the middle

The frame is shimmed plumb at both hinge sets and at the strike, fastened through the shims, and then the gap between the two leaves is checked top to bottom. That centre reveal is the one thing everyone looks at afterwards and it is the hardest thing to fix later.

Watch for: A tapered centre gap — wider at the top than the bottom or vice versa. It means the unit is racked, and shimming after the trim goes on is far harder than shimming before it.
Threshold, sill pan and weather seal on exterior pairs

A sill pan under the threshold drains anything that gets past the door back outside. The threshold is then adjusted so both leaves compress their sweeps evenly, and the perimeter is insulated and flashed.

Watch for: No pan under a glazed pair. French doors present a lot of glass and two sweeps to the weather, and the bottom corners are where water finds its way in.
Hardware, glass and finishing

Handles, deadbolt and any multipoint mechanism are fitted and tested; on exterior pairs the glass is tempered as standard. Trim goes on inside and out, and the doors are cycled repeatedly to confirm they still close evenly.

Watch for: Doors that meet at the top but not the bottom after a few dozen cycles. Glazed leaves are heavy and hinges settle. Ask for a follow-up adjustment to be part of the deal.

Money

What does french door installation cost?

French door installation typically runs $1,500 to $7,000 fitted. Labour alone on a straightforward same-size exterior pair is a few hundred dollars; converting a slider opening, widening, or specifying multipoint locking and clad wood pushes it toward the top.

See the full french door installation cost guide — by material, size and region →

Straight answer

When french door installation is the wrong call

Everyone else ranking for this is paid when you say yes. Here's when you shouldn't.

The room does not have the floor space. Two leaves claim a swing arc permanently. If a chair, a sofa back or a walkway sits inside it, you will end up using one leaf forever and you should have bought a slider.
It is an exposed elevation in a windy spot. A glazed leaf caught by wind is heavy and slams hard. If the doorway takes the prevailing weather, either specify out-swing with restraints or accept a slider is the more practical answer.
You are converting a slider opening on a tight budget. Slider and French openings are rarely interchangeable. Reframing the header and stud pack is real carpentry, and it is nearly always more than the difference in door price.
You want maximum security on a ground-floor rear entry. A pair with a bolted inactive leaf and a lot of glass is inherently a weaker point than a solid single door. It can be specified well — laminated glass, multipoint locking, proper bolt sockets — but that costs money that a single door does not need.
You need the doorway clear for accessibility. A pair narrows to a single leaf in normal use, and thresholds on exterior pairs stand proud. Width and threshold requirements are covered properly by Aging in Place, and that is where to start rather than here.

Your options

Types of french door installation

French vs sliding patio doors

Floor space, weather and traffic, compared honestly.

Impact-rated doors

Glazed pairs in high-wind and coastal zones.

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Straight answer

Can I do this myself?

A tall glazed leaf that gets away from you falls onto tempered glass and onto whoever is holding the other side. If you are attempting this yourself, it is a two-person job with the glass supported, not a one-person job with a helper on standby.

Reasonable to DIY

Removing the old door, trim and threshold, and getting the opening back to bare framing
Checking the opening for square and level, and recording the measurements before you order

Call a licensed pro

Setting the unit itself — a glazed pre-hung pair is heavy, needs at least two people, and every install instruction published says so for a reason
Any opening that is out of square, has a deflected header, or is being converted from a slider
Multipoint lock installation and adjustment, where the strikes have to line up at several heights at once

Before you sign

What to check when hiring for french door installation

Which leaf will be active, and can you confirm that on site before ordering?

Handing cannot be changed after manufacture on a pre-hung pair. Getting it backwards means living with the wrong door for the life of the unit.
In-swing or out-swing, and if out-swing, what hinges are you using?

Out-swing exterior doors need non-removable-pin or security-stud hinges. Ordinary hinges on an out-swing door can be pulled apart from outside.
How do the flush bolts on the inactive leaf engage top and bottom?

Proper sockets in the head jamb and threshold are what stop the pair rattling and flexing. Bolts that merely bear on a surface are the reason a French pair feels loose after a year.
What locking is specified — a single deadbolt or a multipoint?

On a tall glazed exterior pair, multipoint locking pulls the leaf into the frame at several heights. It improves both security and the weather seal, and it is worth pricing rather than assuming.
Will you come back to adjust the doors after they have settled?

Glazed leaves are heavy and hinges bed in. A follow-up adjustment in the first few months is normal, and you want it agreed rather than argued.

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Related work

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Interior Door Installation

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Go deeper

Guides & terms

Guides

How to measure a door

All doors guides →

Terms on this page

Pre-hung door

Full doors glossary →

FAQ

French Door Installation — questions people ask

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What is the difference between interior and exterior French doors?

They are genuinely different products. Interior pairs are lighter, usually single-glazed or with decorative glass, have no weather seal, no threshold to speak of and simple hardware — they divide rooms. Exterior pairs are insulated, tempered-glazed, weather-stripped, sit on a drained threshold and carry security hardware. An interior pair fitted to an outside wall will leak, bow and fail; an exterior pair used inside is heavy and expensive overkill.

Should French doors swing in or out?

In-swing is the US default and keeps the hinges inside where they cannot be tampered with. Out-swing sheds weather better, is common in wet and windy locations, and gives you back the floor space inside. If you choose out-swing, insist on non-removable-pin or security-stud hinges — otherwise the pins are accessible from outside. Either way, mark the swing arc on the floor with tape before you decide.

Can I replace a sliding door with French doors?

Yes, but treat it as a framing job rather than a door swap. Slider and French openings are rarely the same rough size, the header often needs attention, and you may lose or gain width in the process. The door price difference is usually the smaller part of the bill. Have the opening assessed before you commit to the idea, and ask whether a permit applies where you live.

Are French doors secure enough for a back entrance?

They can be, but not by default. The weak points are the glass beside the lock, the inactive leaf held only by flush bolts, and short screws in the strike. Specify laminated glass, multipoint locking that engages at several heights, proper bolt sockets in the head and threshold, and screws long enough to reach the framing behind the jamb. Done that way a pair is respectable; done to the base specification it is the easiest door on the house.