Egress Window Compliance Checker

The dimensional requirements for an emergency escape and rescue opening, reported line by line rather than as one verdict. Net clear opening width against 20 inches. Net clear opening height against 24 inches. Net clear opening area against 5.7 square feet, or 5 square feet where the opening qualifies as a grade floor opening. The height from the finished floor to the bottom of the clear opening against a maximum of 44 inches. Whether the opening is operable from inside without keys, tools or special knowledge. And, where the opening sits below the adjacent grade, the area well: horizontal projection, width, area, whether the well lets the window open fully, the well's vertical depth, and where that depth calls for it, the ladder's width, projection and rung spacing.

Because that measurement, and not the storey the room is on, decides which area requirement applies. A grade floor opening is a defined term: an opening whose sill height is not more than 44 inches above or below the finished ground level adjacent to it. Only a grade floor opening gets the reduced 5 square foot minimum. This is the single most misquoted part of the requirement, because the reduction is often described as applying to anything at or below grade. A deep basement window with its sill 5 feet below the outside ground is well below grade and is not a grade floor opening, so it needs the full 5.7 square feet. The tool takes the measurement and derives the classification rather than asking you to classify the opening yourself.

Because the three figures are independent minimums rather than a formula. The minimum height is 24 inches, the minimum width is 20 inches, and 24 multiplied by 20 is 480 square inches, which is 3.33 square feet — well short of the 5.7 square feet, and short of the 5 square feet too. Meeting the area means exceeding at least one of the dimensional minimums, usually by a lot. A 20-inch-wide opening needs to be roughly 41 inches high to reach 5.7 square feet. The tool calls this case out by name when it happens, because it is the most common way a window that looks compliant on a schedule is not.

It is the free area a body can pass through with the window fully open in its normal operating position — not the rough opening, not the frame, and not the catalogue size. The dimensions have to be the result of normal operation, so an opening reached only by removing a sash or a mullion does not count. Window type changes this enormously. A casement swings its whole sash clear, so the net clear opening is close to the full frame opening. A horizontal slider gives up half its width to the fixed panel. A single-hung gives up half its height. Two windows with the same catalogue size can land on opposite sides of the requirement, which is why the tool asks for measured clear dimensions rather than a product size.

Because the figure that triggers the ladder requirement is the well's vertical depth, not the distance from the well floor down from grade — and those are different numbers whenever the well wall stands proud of the ground. The code commentary gives the case directly: a well floor 40 inches below grade, inside a well whose wall projects 6 inches above grade, has a vertical depth of 46 inches and requires a ladder or steps, even though the part below grade is under the 44-inch threshold. Asking for one number called depth invites the wrong one. Asking for both and adding them does not.

It can, and this is one of the few code items that can be broken years after an inspection passed, without anybody touching the window. Bars, grilles, covers, screens and similar devices placed over an escape opening or the well serving it are permitted, but the required net clear opening size still has to be achieved with the device in place, and the device has to be releasable or removable from inside without a key or a tool and without force greater than the normal operation of the opening. A bolted grille, a keyed security bar or a well cover that has to be lifted from outside converts a compliant opening into a non-compliant one. The tool asks about both conditions separately, because a device can satisfy one and fail the other.

No. It is a preparation aid that performs arithmetic on measurements you take and answers you give. It asserts no product specifications and makes no finding about whether a room is a sleeping room, whether an exception applies to your building, or whether the dwelling's sprinkler arrangement changes the requirement. The thresholds are those of the model residential code for emergency escape and rescue openings; the edition your jurisdiction has adopted is the one that governs, and jurisdictions amend this section. A blank measurement is reported as not measured and excluded rather than filled with an assumption. The determination belongs to the building official, and the scope belongs to the permit.