What is a French door?

A French door is a tall, hinged glazed door that reaches the floor, usually arranged as 2 leaves—a double door. NYC’s architectural glossary also calls it a French window. For replacement work, identify whether the existing frame can stay or must come out with the door.

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By InstaBids editorial team with AI research agents. Updated 3 November 2026

What this means for your home project

Check whether your French door fits snugly; list the door, frame, hardware and seals separately for the repair assessment. Source: Natural Resources Canada, read 2026-11-03.
Ask the installer to state in the written scope whether the existing frame has deteriorated and whether it is properly sealed and insulated before proposing an insert. Source: Natural Resources Canada, read 2026-11-03.
Request a written breakdown of labor and materials so each bid shows the two parts separately. Source: U.S. Environmental Protection Agency (ENERGY STAR), read 2026-11-03.

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What’s the difference between a French-door patio door and a sliding glass patio door?

A hinged French door rotates open; a sliding patio door moves horizontally within its frame. Compare the operating mechanism rather than treating every glazed patio door as the same type. NYC’s architectural glossary describes the French form as floor-reaching and usually paired. “Sliding Glass Door: A Door that contains one or more manually operated glass panels that slide horizontally within a common frame, categorized with the NFRC product code DDSG.” Source: U.S. Environmental Protection Agency (ENERGY STAR), read 2026-11-03. “Swinging Door: A Door system having a hinge attachment of any type between a leaf and jamb, mullion, or edge of another leaf or having a single, fixed vertical axis about which the leaf rotates between open and closed positions.” Source: U.S. Environmental Protection Agency (ENERGY STAR), read 2026-11-03. “French door or French window: A tall casement window that reaches to the floor, usually arranged in two leaves as a double door.” Source: New York City Landmarks Preservation Commission, read 2026-11-03.

How do you draught proof French doors?

Check the seals at the frame and sill before specifying draft repairs for exterior French doors. Canadian residential guidance describes V-shaped vinyl at the frame and a gasketed door-bottom seal or threshold weatherstripping at the sill. The sill is the bottom of the doorway. “The easiest and most effective weatherstripping for a door frame is a good quality V-shaped vinyl type (see Figure 8-11, image B), which makes contact with the edge of the door and provides a good seal even when the door warps from season to season.” Source: Natural Resources Canada, read 2026-11-03. “A good seal can usually be obtained with gasketed door-bottom weatherstripping that attaches to the door, or with full or partial threshold weatherstripping that is attached to the door sill.” Source: Natural Resources Canada, read 2026-11-03.

Can a damaged French door be repaired?

A repair assessment should separate the door, frame, hardware and seals. Canadian guidance calls for fixing or replacing those parts when the door does not fit snugly; it also identifies poor installation, hard use, foundation movement and seasonal warping as possible causes of misalignment. “Poor installation, years of hard use, shifting foundations and seasonal warping can often force hinged doors and sliding glass patio doors to become out of square with their frames.” Source: Natural Resources Canada, read 2026-11-03. “If doors do not fit snugly, fix or replace the door, frame, hardware, gaskets and weatherstripping.” Source: Natural Resources Canada, read 2026-11-03.

How can I ensure my French doors are energy-efficient?

For an exterior hinged French door, use ENERGY STAR specification 7.0’s swinging-door criteria, which depend on glazing level—the amount of glass. Compare U-factor, the rate of heat transfer: a smaller value means better insulation. Installation also matters; a poorly installed door can still be drafty. “Swinging doors shall meet the criteria for a given glazing level.” Source: U.S. Environmental Protection Agency (ENERGY STAR), read 2026-11-03. “U-Factor measures the rate of heat transfer and tells you how well the window insulates.” Source: U.S. Environmental Protection Agency (ENERGY STAR), read 2026-11-03. “The lower the U-factor, the better the window insulates.” Source: U.S. Environmental Protection Agency (ENERGY STAR), read 2026-11-03. “Even the best windows, doors, and skylights can be drafty if they are poorly installed.” Source: U.S. Environmental Protection Agency (ENERGY STAR), read 2026-11-03.

What factors affect French door installation cost?

Frame condition and the installation method change the scope being priced. Canadian guidance distinguishes an insert, which keeps the existing frame, from a complete tear out, which removes it. An insert is suitable only when that frame has not deteriorated and is properly sealed and insulated. Ask for those two scopes to be distinguished in writing. “An insert retrofit involves installing a new window or door into the frame of the existing window or door that is being replaced.” Source: Natural Resources Canada, read 2026-11-03. “However, an insert should be done only if the existing frame has not deteriorated and is properly sealed and insulated.” Source: Natural Resources Canada, read 2026-11-03. “A complete tear out involves removing the old window, door or skylight, including the frame.” Source: Natural Resources Canada, read 2026-11-03.

Sources

Architectural glossary — New York City Landmarks Preservation Commission; read 2026-11-03.
Keeping the Heat In: Section 8, Upgrading windows and exterior doors — Natural Resources Canada; published 2025-01-14; read 2026-11-03.
Residential windows, doors and skylights — U.S. Environmental Protection Agency (ENERGY STAR); read 2026-11-03.
Energy performance ratings — U.S. Environmental Protection Agency (ENERGY STAR); read 2026-11-03.
Residential windows, doors and skylights: Version 7.0 eligibility criteria — U.S. Environmental Protection Agency (ENERGY STAR); published October 2022; effective October 23, 2023; read 2026-11-03.