Egress Window Code Verification Before Order Release

Purpose

This procedure decides, before a purchase order leaves the office, whether a replacement unit going into a sleeping room or a basement will still be a legal emergency escape and rescue opening after it is installed. It exists because the clear opening a body passes through is not the size on the order. An insert unit sets a new frame inside the old one and gives back an inch or more of clear width and height, and sometimes two to three, so a bedroom window that was marginal before the job is undersized after it, and nobody finds out until a resale inspection or a fire. The shop that measured the frame instead of the opening owns the re-do: new unit, new labor, and on a full-frame correction, siding and drywall it never bid. It also guarantees a written basis for the call, because the exemption most replacement work leans on has conditions.

Scope

Covers every operable unit in a room used for sleeping and every basement with habitable space, measured on site before order release, for like-for-like replacement in an existing dwelling. Covers window well geometry for below-grade openings.

Does not cover enlarging a rough opening. Cutting a header, a masonry opening, or a new well is structural and permit-bearing work that belongs to the opening-enlargement SOP. Does not cover the fall-prevention hardware decision on an upper-floor unit; that sits in the final operation and lock verification SOP, which owns the release-and-full-opening check on any opening control device fitted to an escape window.

Roles and responsibilities

The verification procedure

1. Identify which openings are in scope, in the house, before measuring anything. Walk the plan with the customer and mark every room used for sleeping now, plus any basement room they describe as finished or intend to finish. Acceptance: every bedroom and basement habitable space has one opening designated as its escape opening. Wrong looks like the customer saying "the den downstairs, my son sleeps there sometimes." That is a sleeping room for this purpose. Stop rule: if a basement finish or a room conversion is part of this work, this is not like-for-like replacement, the exemption path in step 6 does not apply, and the file goes to the owner before measuring continues. Hazard: unfinished basements have open joists, standing water, and unguarded sump pits. Carry a light, keep both hands free, and never step on a covered pit lid to reach a window.

2. Measure the existing net clear opening with the sash fully open, twice. Open the operating sash to its stop and measure the unobstructed width and height a body passes through, not the frame, not the glass, and not the catalog size. On a double hung the clear height is limited by the bottom of the raised sash. Acceptance: two independent measurements agreeing within 1/8 in, recorded to the nearest 1/8 in. Wrong looks like a single number written down from memory in the truck. Stop rule: if the sash will not reach its stop because of paint, a broken balance, or a security pin, do not force it and do not measure a partial opening; note the obstruction and flag the file for a revisit. Hazard: on any house built before 1978, do not scrape, sand, or chip painted sash or stops to free them. That disturbance is regulated work under the EPA Renovation, Repair and Painting rule at 40 CFR Part 745 Subpart E and requires a certified firm and a contained work area.

3. Measure the sill height above the finished floor. Measure from the finished floor to the bottom of the clear opening, not to the stool or the apron. Acceptance: 44 in or less, the maximum sill height for an escape opening in the IRC at Section R310. Wrong looks like measuring off a subfloor in a room that is getting carpet, which moves the number the wrong way by up to an inch. Stop rule: over 44 in, unit selection cannot fix it and the file goes to the owner as an opening-modification question. Hazard: measuring a basement sill means standing on something. Use a rated step stool on a level surface, never a bucket or stacked material.

4. Probe to the framing and record the true rough opening. Pull one stop or one piece of interior casing at a corner, measure jamb-to-jamb and head-to-sill on the framing, then reinstall it. This is what a full-frame unit has to fit and it is routinely half an inch off the trim-to-trim number. Acceptance: rough opening width and height recorded, plus a note on frame condition at the sill. Wrong looks like deriving the rough opening by adding an allowance to the existing frame. Stop rule: rotted sill framing or a bowed jamb means the opening size is not yet known; photograph it, quote the framing repair separately, and hold the order. Hazard: do not drive a probe or a blade blind into a wall cavity beside a window. Branch wiring is commonly run in the stud bay next to an opening; open the casing by hand with a flat bar and look before any blade goes in.

5. Compute the area and compare both candidate units to the code minimum. Take the manufacturer's published clear opening for the specific unit and operating style quoted, multiply width by height in inches, divide by 144 for square feet, and compare against the IRC Section R310 minimums in the edition your jurisdiction has adopted: a net clear opening of 5.7 sq ft, with an exception permitting 5.0 sq ft for grade-floor and below-grade openings, a clear height of at least 24 in, and a clear width of at least 20 in. Do the insert candidate and the full-frame candidate separately; they are different numbers. Acceptance: the selected unit meets all three on the published figure, not a derived one. Wrong looks like using the nominal call size, which is a frame dimension and always larger than the opening. Stop rule: fail any of the three and the order is not released; go to step 6.

6. Where the new-construction minimum is not met, establish the replacement-window basis in writing or stop. The IRC at Section R310 carries a replacement-window provision exempting a replacement from the opening size and sill height requirements when the unit is the manufacturer's largest standard size that fits the existing frame or rough opening, the operating style gives an equal or greater opening than the existing, and the work is not part of a change of occupancy. Acceptance: the file carries the published clear opening of the largest standard size that fits, the existing measured opening beside it, and a dated note of the AHJ's response naming the person spoken to. Wrong looks like a verbal "they never check that" from anyone. Stop rule: no AHJ confirmation, no order release. Where the job is part of a basement finish or a change of use, the exemption does not apply and the file goes to the owner as an opening-enlargement scope.

7. Verify the window well on any below-grade opening. Measure the well's clear horizontal area, its projection from the foundation, and the depth from grade to the well floor. Acceptance: at least 9 sq ft of area with a minimum horizontal projection and width of 36 in, and for a well deeper than 44 in, a permanently affixed ladder or steps that stay usable with the window fully open. Wrong looks like a corrugated well half filled with drain rock, which reduces depth honestly but buries the escape floor. Stop rule: an undersized well makes the opening non-compliant regardless of the unit, so the well correction is quoted with the window or the escape designation moves to another opening in that room. Hazard: never enter a well deeper than chest height without a second person present and a way out that does not depend on the window you are about to remove.

8. Release the order line with the determination attached. The order desk stamps the line with the compliance path taken, the measured numbers behind it, and the name of whoever confirmed the exemption. Acceptance: no egress-designated line ships without all three. Wrong looks like a released order whose notes field says "egress OK." Stop rule: an unstamped egress line is held, and the hold reaches the salesperson the same day so the customer's schedule expectation moves with it.

The record this produces

The measure sheet carries, per opening: room, escape designation, existing clear width and height and area, sill height above finished floor, rough opening dimensions, sill framing condition, well area and depth where applicable, candidate unit with its published clear opening and computed area, compliance path (meets R310 outright, or replacement-window basis), and the AHJ contact name and date where the second path was used. Photographs of the open sash with a tape in frame, the sill measurement, and the well attach to it.

It lands on the job record against the customer, not in the estimator's notebook, and three people read it later: the order desk at release, the install lead the morning a delivered unit does not match, and whoever answers the phone in two years when a home inspector writes up the bedroom window during a sale. That last reader is why the AHJ contact name is a field and not a memory.

Worked pass: a second-floor bedroom, like-for-like

A 1978 two-story, one bedroom unit quoted, wood double hung, painted but operating. Step 1 marks the room as a sleeping room, one escape opening, no basement work in scope. Step 2 opens the sash to its stop and measures the clear opening twice at 28-1/2 in wide by 26 in high, both times, so 741 sq in, which is 5.15 sq ft. Step 3 measures the sill at 41 in above the finished hardwood, under the 44 in maximum. Step 4 pulls the left stop and finds the rough opening at 32-1/4 in by 58 in with sound sill framing.

Step 5 fails. The quoted insert unit publishes a clear opening of 27-1/4 in by 25-3/8 in, which is 691 sq in, or 4.80 sq ft. That is under the 5.7 sq ft minimum and it is also smaller than the 5.15 sq ft opening that exists today, by about 7 percent. The full-frame candidate for the same rough opening publishes 28-1/8 in by 26-3/4 in, which is 752 sq in, or 5.22 sq ft. Clear width 28-1/8 in clears the 20 in minimum and clear height 26-3/4 in clears the 24 in minimum, but 5.22 sq ft still does not reach 5.7 sq ft. Both candidates fail the step, so the order is not released and the file goes to step 6.

Step 6 establishes the basis. The full-frame unit at 5.22 sq ft is the manufacturer's largest standard size that fits this rough opening, it is the same operating style, and it is larger than the existing opening rather than smaller, with no change of occupancy in scope. The owner calls the building department, gets confirmation from a named plans examiner that the replacement provision applies, and the name and date go on the file. Step 7 does not apply on a second floor. Step 8 releases the line stamped with the replacement-window path and both areas printed.

The insert candidate is the one worth naming. It was the cheaper unit, it fit the existing frame, it needed no siding work, and it would have made a marginal escape opening about 7 percent smaller. Neither the customer nor the crew would have noticed. Step 2 is the only thing in this procedure that catches it.

References

1. International Residential Code, Section R310 (Emergency Escape and Rescue Openings), in the edition adopted by your authority having jurisdiction, including its replacement-window provision and window well requirements.
2. EPA Renovation, Repair and Painting Rule, 40 CFR Part 745 Subpart E, for disturbance of painted surfaces in pre-1978 housing.
3. Manufacturer's published clear opening tables for the specific unit and operating style; nominal call sizes are frame dimensions, not clear openings.
4. See related: the final operation and lock verification SOP, which owns the release-and-full-opening check on any opening control device fitted to an escape window.