The Egress Window and the Trades That Quietly Defeat It

Why this matters

A bedroom window is the second way out of a room whose door may open onto a hallway full of smoke, and it is the way a firefighter comes in. It does that job only if a sleepy adult or a child can open it without a key or a tool and fit through what opens. Window installers know the rules. The trades that defeat egress are everyone else: the HVAC tech who sets a window unit in the only bedroom window, the handyman who bolts on security bars, the painter who paints the sash shut, the landscaper who drops a heavy grate on a window well, the deck builder who covers the well entirely. Each one leaves the window looking fine.

This card owns egress for trades that are not installing windows. Code compliance for a window being installed or replaced is covered by 'Egress Window Code Compliance Per IRC R310'; this card is about not making an existing opening worse.

What the opening has to provide

The 2021 IRC, in R310 as adopted by your jurisdiction, requires an emergency escape and rescue opening in every sleeping room and in basements and habitable attics, with exceptions your local code may add or remove. The figures below are the 2021 edition's; other editions and local amendments can differ.

        |<-- clear width, 20 in min -->|
   +----+------------------------------+----+
   |    |                              |    |
   |    |  NET CLEAR OPENING           |  clear
   |    |  5.7 sq ft min               | height
   |    |  5.0 sq ft min at grade      | 24 in
   |    |  floor or below grade        |  min
   |    |                              |    |
   +----+--------------+---------------+----+
        |  sill: bottom of the clear    |
        |  opening, 44 in max above     |
        |  the finished floor           |
   =====+===============================+==== FLOOR

Four things about that drawing trip people up.

The minimums do not add up to the area. A 20 in by 24 in opening is 480 sq in, which is 480 / 144 = about 3.3 sq ft, far short of 5.7. At the minimum width of 20 in, the opening needs to be about 41 in tall (5.7 x 144 = 820.8 sq in, and 820.8 / 20 = 41.0 in); at the minimum height of 24 in it needs to be about 34 in wide. The width and height are floors on each dimension; the area is a separate test.

It is the net clear opening, measured with the window open. Not the frame, not the glass. On a double-hung or a slider, only one sash moves, so the clear opening is roughly half the window. On a casement it is nearly the whole sash, minus the hinge side.

The sill is measured to the bottom of the clear opening, from the floor. A built-in bench or a raised platform under the window does not lower the sill for code purposes unless your jurisdiction says otherwise; the measurement is from the finished floor of the room.

It has to open from inside without a key, a tool or special knowledge. That is the part other trades break most often, and none of them add up a single square inch to do it.

Window wells serving a below-grade opening have their own rules in the same section: in the 2021 edition, a well needs at least 9 sq ft of area with at least 36 in of horizontal projection and width, and a well deeper than 44 in needs a permanently attached ladder or steps that the open window does not block.

The defeats, trade by trade

Window air conditioners. A unit in a double-hung window fills the lower half of the only opening that moves. Unless the room has a second compliant opening, it has no escape window while the unit is in. See 'How to Place a Window Air Conditioner Without Blocking the Only Egress'.

Security bars, grilles and screens. R310 permits them over an escape opening, provided the device releases or comes off from the inside without a key, a tool, special knowledge or more force than it takes to open the window normally, and provided the opening still meets the size rules once it is released. Fixed bars bolted to the masonry, padlocked grilles and screwed-on security screens fail. See 'How to Check Bars, Grilles and Well Covers for Release From Inside'.

Paint and fasteners. A sash painted shut, nailed for winter, or screwed to the frame "for security" is a window that no longer opens. A painter who finds a sash stuck by old paint should not leave it stuck by new paint; break the film with a sash knife on both sides before you leave, or note it for the homeowner.

Removed crank handles. A casement whose operator handle was taken off, often because a child kept opening it, now needs a tool and special knowledge to open. The handle goes back on, or a listed window opening control device replaces the workaround.

Child window stops. A window opening control device listed to ASTM F2090 is meant to limit a window to a few inches for fall protection while still releasing to full opening without a tool, and the IRC accepts it on an escape window on that condition. A wooden block screwed into the track, or a stop that needs a key, is not that device.

Furniture and built-ins. A dresser, a bunk bed or a built-in desk under the window does not change the code measurement, but it is the practical reason a child cannot reach the latch. A closet builder or cabinet installer should not build across a bedroom window. Movers and cleaners who rearrange a bedroom can at least say so.

Window well covers. Landscapers and handymen install covers to keep leaves, rain and children out of a well. A cover is fine if a person inside the well can push it open without a tool or a key and without more force than the window itself takes. A heavy steel grate, a cover bolted down, or a cover with a heavy planter set on it fails.

Decks and porches over a well. A deck built over a basement window well can make it impossible to climb out. The 2021 IRC addresses openings under decks and porches in R310, and the general requirement is that the opening can fully open and there is a clear path out to a yard. Deck builders who meet a window well under the footprint should stop and ask before framing over it.

Storm windows and fixed inserts. An exterior storm panel fixed in place, or an interior insert for energy savings, can turn an openable window into a sealed one.

Worked example: a basement bedroom, a grate and a set of bars

A handyman is booked to install security bars on a basement bedroom window in a house the owners are about to rent out, and the same week a landscaping crew is scheduled to put a cover on its window well. The handyman measures before he drills anything.

The window. A horizontal slider. With the moving sash fully open, the clear opening measures 27 in wide by 30 in high, and the bottom of the opening is 42 in above the finished basement floor.

• Area: 27 in x 30 in = 810 sq in; 810 / 144 = 5.625 sq ft.
• Width 27 in, at or above 20 in: passes.
• Height 30 in, at or above 24 in: passes.
• Sill 42 in, at or below 44 in: passes.
• The room is below grade, so the 5.0 sq ft figure applies: 5.625 is at or above 5.0, passes.

Checking the area the other way: 5.625 sq ft x 144 = 810 sq in, and 810 / 30 = 27 in. Note what the grade-floor figure did. The same window on a second-floor bedroom would fail, because 5.625 is below 5.7. That is not a reason to leave it alone in the basement; it is a reason to protect every inch it has.

The well. 36 in of projection from the foundation, 40 in wide, 48 in deep from grade to the well floor.

• Area: 36 in x 40 in = 1,440 sq in; 1,440 / 144 = 10.0 sq ft, at or above 9 sq ft: passes.
• Projection 36 in and width 40 in, each at or above 36 in: passes.
• Depth 48 in, more than 44 in, so a ladder or steps are required. There is a ladder bolted to the well wall, and the open sash does not cover it: passes.

The bars. The owners bought a fixed set that bolts into the concrete. The handyman explains that fixed bars on this window take away the room's only escape, and that the code allows bars here only if they release from inside without a key or tool. He offers a quick-release set with an interior lever and confirms, after installing it, that one push on the lever swings the bars clear of the full 27 by 30 opening with no more effort than sliding the sash.

The well cover. He calls the landscaping company and the owner the same day: whatever cover goes on has to lift from inside the well with a hand, without a tool, and must not be weighted down. A light hinged polycarbonate cover passes that test; the heavy steel grate on their quote does not.

What goes on the work order. The four window measurements and three well measurements, the release check on the bars, and the note to the owner and landscaper about the cover. If the owners refuse the quick-release bars and install the fixed set themselves, he writes that he advised against it and why. See 'The Life-Safety Deficiency Notice SOP'.

What changes the answer

A second compliant opening. A room with two escape openings can lose one to a window unit for a season and still have a way out. That is a reason to check, not an assumption.

An existing window that is already undersized. Many older homes have bedroom windows smaller than current R310 figures that were legal when built and are not required to be changed. Your job is not to bring them up to today's code; it is not to make them worse. Replacing that window is the point where the rules apply again: the 2021 edition lets a replacement window skip the size and sill rules only when it is the manufacturer's largest standard size that fits the existing frame or rough opening, in the same or a larger-opening style, and the work is not part of a change of occupancy.

Local amendments. Some jurisdictions change the sill height, the area, the treatment of bars, or the rule for basements without bedrooms. The local code governs.

References

• 2021 International Residential Code, Section R310 (emergency escape and rescue openings), as adopted and amended by your jurisdiction, for opening dimensions, sill height, window wells, devices over openings, openings under decks, and replacement windows.
• ASTM F2090, the standard for window opening control devices, which the IRC references for fall protection devices permitted on escape windows.
• See related: Egress Window Code Compliance Per IRC R310.
• See related: How to Measure an Egress Window Net Clear Opening.
• See related: Why Every Trade Owes the Life-Safety Devices in a House.