Dog Door in a French Door: Options, Sizing and Locks

How-to · 3 min read · Updated October 2026

Yes, but not by cutting the glass yourself. The usual routes are a glass insert with a dog door built in, or a glazier fitting a custom door in place of a pane.

What works depends on your door and your dog. Start by looking at how many panes you have.

Dog door options for a French door: one big pane swapped for glass with a dog door built in, several panes with one or more removed for a custom door, a cut-in below the glass for a small dog, hire a glazier — Three routes, one rule: hire a glazier. Based on: PetDoors.com, 2018, a seller.

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The options

A seller, PetDoors.com, says most French door glass is a single pane, either one sheet with grid-work or several separately framed panes.

With one sheet, you swap the pane for one with the dog door in its bottom, or have the pane removed, the insert installed and the pane put back.

With separate panes, a glazier removes one or more and fits a custom door in the opening. A larger dog may need more than one pane taken out. For small dogs, a cut-in below the glass may work instead.

The post calls the job “not a DIY task” and recommends a local glazier. It does not address tempered glass, so ask the glazier what your door has.

White dog looking out through a glass door — Know your dog’s height before you shop. Photo: David Brown on Pexels.

Choosing the dog door

Home Depot’s buying guide says to measure your dog from shoulder to floor, and to skip the head, since many dogs duck. Check the stepover, the gap between the flap’s bottom edge and the floor, and pick a door rated for your dog’s size and weight.

It says energy-efficient models usually have two or more thicker flaps, magnetic closures and weatherstripping, while lightweight vinyl flaps cost less but can warp and let in air and insects.

Choose a dog door: measure shoulder to floor, check the stepover, pick a rated size, look for two or more flaps, magnets and weatherstripping, add a lock for night — Five checks before you buy. Source: Home Depot, 2023.

Security and locks

The same guide says to look for a lock or lockable panel to keep the door shut overnight or when you have guests. Large dog doors may be big enough for a person, so a lock or sensor-activated design is worth considering.

Electronic doors that read a microchip or collar can keep out other animals. They stop working in a power outage, so a battery-powered one may be the better pick.

My call · James Davis

On a French door I would look at a wall or a side door before putting a flap in the glass. A cut pane is a permanent change, and a lockable flap is only as good as the lock you use.