How to Add French Doors to an Exterior Wall or Window Opening

Swapping a worn door for a new one is a weekend job, but when you add french doors where there is currently a solid wall or a window, you are changing the structure of your house. The opening has to get wider, and usually taller, which means removing studs that carry load from the roof or floor above. That load must be transferred to a properly sized header and new jack studs before the old framing comes out.

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Here is the direct answer. Adding French doors is doable for an experienced DIYer on a single-story wall with a building permit, temporary shoring, a correctly sized header, and careful flashing at the sill. Most homeowners hire a contractor for the structural cut and do finish work themselves. Expect the project to take a few days of framing and installation, plus inspection time, and plan for siding, drywall, trim, and paint repairs around the new opening.

This guide focuses on creating a new opening from a wall or enlarging a window. If you already have a French door and are simply replacing french doors of the same size, the job is far simpler and skips most of the structural steps described here.

Before You Add French Doors: Planning and Permits

Nearly every jurisdiction requires a building permit when you cut a new opening in an exterior wall or widen an existing one, because a header change affects structural load paths and the building envelope. The permit office may ask for a simple drawing showing the opening width, header size, and door specifications. An inspector typically checks framing before you close up the wall.

Work through these questions early:

• Is the wall load-bearing? Exterior walls under roof eaves almost always carry roof loads. Gable-end walls may carry less, but still need a header. When in doubt, treat the wall as load-bearing.
• What is inside the wall? Check for wiring, plumbing, ductwork, or gas lines. Outlets, switches, and vents on either face are clues. Rerouting these is often the hidden cost of the project.
• How old is the house? Homes built before 1978 may have lead paint on siding, trim, and interior walls. Plaster, joint compound, and some siding in homes from before the 1980s may contain asbestos.
• What size door? Common double French doors are 60 or 72 inches wide and 80 inches tall. The rough opening is usually about 2 inches wider and 1 to 2 inches taller than the door unit; the manufacturer lists exact rough opening sizes.
• HOA and exterior appearance. Some associations regulate new exterior doors and glass.

Header Sizing Basics

The header spans the top of the opening and carries the load that the removed studs used to support. Its size depends on the span, the load above (roof only, roof plus one floor, snow load), and the lumber species. Wider openings need deeper headers.

For a typical 6-foot French door opening supporting only a roof in moderate snow country, builders often use a doubled 2×10 or 2×12 header with a half-inch plywood spacer for a 2×4 wall, but that is only a starting point. Two stories of load or heavy snow may call for engineered lumber such as LVL. Use the header span tables in your locally adopted residential code, or ask the permit office or a structural engineer. Never guess on header size, and never reuse a smaller window header for a wider door.

Each end of the header rests on jack (trimmer) studs, which sit beside full-height king studs. Wider headers or heavier loads may require doubled jack studs. The load then travels down through the bottom plate into the floor framing and foundation, so confirm the floor framing below can support concentrated point loads at each side.

Tools and Materials

• Prehung French door unit with correct swing (inswing or outswing) and handing
• Header lumber or LVL, king and jack studs, plywood spacers
• Temporary shoring: 2×4 or 2×6 posts and top/bottom plates, or adjustable steel shores
• Reciprocating saw, circular saw, oscillating multi-tool
• Framing nailer or structural screws, hammer, pry bar
• Level (6-foot is ideal), square, tape measure, chalk line
• Self-adhered flashing tape, sill pan or preformed sill flashing, drip cap
• Composite or rot-resistant shims, low-expansion window and door foam
• Exterior sealant, trim, and siding repair materials
• Non-contact voltage tester, safety glasses, gloves, hearing protection, dust mask or respirator

Step-by-Step: Cutting the Opening and Installing the Door

1. Test for Hazards and Prep the Area

In pre-1978 homes, test the paint for lead before cutting or sanding. If lead is present, follow lead-safe work practices: plastic sheeting, misting, HEPA vacuuming, and no dry sanding or power planing. If plaster, joint compound, or siding could contain asbestos, have samples tested before disturbing them. Cover floors and seal off the room with plastic.

2. Disable Utilities in the Wall

If any wiring runs through the section you will remove, turn off the breaker and confirm power is off with a non-contact voltage tester before touching it. Relocating outlets or adding circuits for exterior lighting should be done by a licensed electrician. Plumbing and gas lines must be rerouted by licensed professionals. Ductwork can sometimes be rerouted through an adjacent bay.

3. Mark and Open the Interior Wall

Mark the rough opening plus room for the new king studs on the interior wall. Remove drywall or plaster to expose the framing from floor to ceiling across this width. Now you can see exactly what the wall holds.

4. Install Temporary Shoring

Build a temporary stud wall about 2 to 3 feet inside the existing wall, running parallel to it, with a top plate snug against the ceiling joists. This carries the load while you remove the studs. On second-floor or heavily loaded walls, shoring may be needed on both sides.

5. Cut the Exterior and Remove Studs

From inside, drill locator holes at the corners of the rough opening. Outside, snap lines and cut siding and sheathing along them; remove siding slightly wider than the opening to allow for flashing and trim. Cut out the studs, and if you are enlarging a window, remove the window, its old header, and the sill framing. Cut the bottom plate out of the door opening last.

6. Frame the New Opening

Install king studs at each side, then jack studs, then set the header on top of the jack studs and nail it through the king studs. Add cripple studs between the header and the top plate if there is a gap. Check that the opening is plumb, level, and square, and matches the manufacturer’s rough opening dimensions. Call for a framing inspection if required before closing things up, and only then remove the temporary shoring.

7. Flash the Sill and Opening

Water intrusion at the threshold is the most common failure of a new exterior door. Install a sill pan or build one from flexible flashing tape so it turns up the sides at least 6 inches and slopes slightly toward the outside. Lap the house wrap and flashing shingle-style so water always runs down and out: sill first, then sides, then head flashing and a drip cap above the door.

8. Set the Prehung Door

French door units are heavy, especially with full glass panels, and they are awkward. Carry them with two people, wear gloves, keep the unit upright, and never let the glass edges strike the ground or flex the frame. Most exterior French doors use tempered or laminated safety glass, which building codes require in doors, but edges remain vulnerable.

Run beads of sealant on the sill pan per the manufacturer’s instructions, tilt the door into place, and center it. Shim behind each hinge and at the latch points so the jambs are plumb and straight and the gap between doors is even. Fasten through the jambs into the framing, replacing one screw per hinge with a long screw that reaches the jack stud.

9. Insulate, Trim, and Finish

Fill gaps between the jambs and framing with low-expansion foam made for doors and windows. Standard foam can bow jambs. Install exterior trim or brick molding, patch siding, and caulk. Inside, repair drywall, add casing, and paint.

Troubleshooting Common Issues

• Doors don’t meet evenly: Adjust shims at hinges or use the adjustment screws many units include. Check that the sill is level.
• Air or water leaking at the threshold: Adjust the threshold height, replace sweeps, and confirm the sill pan drains to the outside.
• Drywall cracks above the door: A small amount of settlement is normal, but widening cracks or a sagging header need a structural assessment.
• Floor height mismatch: Plan transitions early. Thick tile or hardwood indoors may require a taller threshold or a raised subfloor so the door swing clears.
• Condensation on glass: Choose insulated, low-E glass suited to your climate.

General Cost Ranges

Costs vary with the door quality, the wall construction, and what is hidden inside it. Converting an existing window is often less expensive than cutting a brand-new opening because a header already exists and utilities are less likely to be in the way. Brick or stucco exteriors cost more to cut and patch than wood or vinyl siding.

The door itself can range from budget steel or fiberglass units to premium wood or aluminum-clad designs. Labor for structural framing, flashing, and installation often matches or exceeds the door cost, and electrical, plumbing, and exterior finish work add more. Permit fees are usually modest compared with the overall project. Get at least two or three itemized quotes that list header size, flashing method, and finish work.

When to Call a Licensed Professional

Hire a licensed general contractor or carpenter when the wall supports a second floor, when the opening exceeds about 6 feet, when the house has brick or stucco cladding, or when you are unsure whether the wall is load-bearing. A structural engineer should size headers for unusual loads, long spans, or where a point load lands on a questionable floor. Licensed electricians, plumbers, and gas fitters must handle any utilities in the wall. For pre-1978 homes where lead is confirmed, look for a lead-safe certified renovator, and use a licensed abatement contractor if asbestos testing is positive.

Many homeowners split the work: a pro handles shoring, framing, and door setting, and the homeowner takes on trim, painting, and landscaping. That approach keeps structural risk with the experts while trimming overall cost. Done right, the new doors will open your space to light and the outdoors for decades.