Replacement Window GuideReplacement windows are installed one of two ways: full-frame, which replaces the frame itself, or insert, also called pocket, which fits a new unit inside the existing frame. This Old House prices insert work at about 100 to 400 dollars per window and full-frame at about 180 to 1,500 dollars. The method you choose depends mostly on the condition of your existing frame, and either way bedroom and basement openings must still meet IRC egress rules.
What full-frame replacement is
This Old House explains that a full-frame replacement window includes a completely new frame that replaces the existing one, including the head, side jambs, and sill. Because the installer removes the old frame down to the rough opening, the job exposes areas that are normally hidden.
That exposure is part of the appeal. This Old House notes full-frame work lets the crew address underlying issues like water damage or poor insulation that would not be visible with an insert install.
What insert (pocket) replacement is
This Old House explains that insert window replacement, also called pocket replacement, fits a new window unit inside the existing frame rather than replacing it entirely. The original frame, trim, and exterior stay in place, which makes the install faster and less disruptive.
Because the new unit sits inside the old frame, This Old House notes insert windows slightly reduce the overall glass area, which can trim natural light. Insert work is best when the existing frame is still square, level, and undamaged.
When to choose each method
The deciding factor is frame condition. This Old House says full-frame becomes appropriate when the existing frame has rot, warping, or structural damage, when you want to change the window's size or style, or when the window is no longer square due to settling.
Insert replacement works best when the frame is still square, level, and undamaged, and when you want a quicker, less disruptive installation. Inspecting the existing frame before deciding avoids sealing a new window over hidden rot.
Cost difference between the methods
The two methods carry different price ranges. This Old House lists insert or pocket replacement at about 100 to 400 dollars per window, and full-frame replacement at about 180 to 1,500 dollars per window depending on the window's size, type, and frame material.
Insert work is the cheaper path when the frame allows it, but the higher ceiling on full-frame reflects the added labor of removing and rebuilding the frame and correcting anything found in the opening.
Energy efficiency tradeoff
The methods also differ on performance. This Old House describes insert replacements as less expensive but also less energy efficient than full-frame, because the old frame and its existing seals stay in place.
Full-frame work replaces everything, which lets the installer air-seal and insulate the full rough opening. If drafts and thermal performance are a priority and the budget allows, full-frame closes gaps an insert leaves behind.
Egress code still applies
Whichever method you choose, bedroom and basement openings must still meet emergency escape rules. Building Code Trainer, citing Section R310.2 of the 2021 International Residential Code, states that emergency escape and rescue openings require a minimum net clear opening of 5.7 square feet, with an exception of 5.0 square feet allowed at grade-floor level.
The same source lists a minimum net clear opening height of 24 inches, a minimum net clear width of 20 inches, and a sill no more than 44 inches above the finished floor. Insert installs matter here, because fitting a smaller unit inside an old frame can shrink the clear opening below what code requires.