Spot the Violation

FramingFire separation, egress & alarmsLevel 22018 IRC

Casement window in a main-floor bedroom

A main-floor bedroom wall with a single tall, narrow white casement window, cranked fully open so the sash stands out square to the frame. Through the opening are a lawn, a spruce tree and sky. A manufacturer's paper tag hanging from the crank handle reads CLEAR OPENING 22.3 W x 40.1 H IN, 6.2 SQ FT. A yellow folding rule stands on the carpet against the wall under the window, and its 43 in. mark lines up with the bottom of the open window. A dresser stands to the left and a small upholstered chair to the right. CLEAR OPENING 22.3 W x 40.1 H IN 6.2 SQ FT 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47
Main-floor bedroom, casement window open

What's wrong here?

  1. Nothing. This installation is compliant
  2. The sill is too high; a bedroom window sill may be no more than 42 in. above the floor
  3. The opening is too narrow; an emergency escape window must be at least 24 in. wide
  4. The window needs a window opening control device because the sill is so high
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Show the answer and the code reference

The answer

Nothing is wrong. The casement gives a 22.3 in. wide by 40.1 in. high clear opening (about 6.2 sq ft), and the bottom of that opening is 43 in. above the floor, which meets every R310.2 requirement.

Correct choice: 1. Nothing. This installation is compliant

R310.2.1 requires an emergency escape window to give at least 5.7 sq ft of net clear opening (5 sq ft for a grade-floor or below-grade opening), at least 24 in. of clear height and at least 20 in. of clear width, all through normal operation from inside. R310.2.2 limits the bottom of the clear opening to 44 in. above the finished floor. This casement gives 22.3 in. by 40.1 in., about 894 sq in. or 6.2 sq ft, and its sill is 43 in. above the floor. A narrow casement that cranks fully open is one of the most efficient escape windows because almost the whole sash area becomes clear opening. The high-looking sill is legal by an inch, so measure it before you write it up, and measure to the bottom of the clear opening, not to the stool or the drywall return.

How to fix it

No correction needed. Keep the crank operator and hardware working so the sash still opens fully, and do not add window treatments or furniture that block it.

Code references

  • IRC 2018 R310.2.2 — Window sill height

    Where a window is provided as the emergency escape and rescue opening, the bottom of its clear opening may be no more than 44 in. above the floor. Where the sill is below grade, a window well complying with R310.2.3 is required.

    Drills citing R310.2.2

  • IRC 2018 R310.2.1 — Minimum opening area

    The opening must give a net clear opening of at least 5.7 sq ft (5 sq ft for grade-floor or below-grade openings) through normal operation from the inside, with a net clear height of at least 24 in. and a net clear width of at least 20 in.

    Drills citing R310.2.1

  • IRC 2018 R312.2.1 — Window sills

    Where the bottom of an operable window's clear opening is less than 24 in. above the finished floor and more than 72 in. above the finished grade or surface below on the exterior, the window must have a fall-prevention device or window opening control device, or the opening must not pass a 4 in. sphere.

    Drills citing R312.2.1

2024 IRC:not yet checked Confidence: low

Minnesota

MN adopts this rule as writtenConfidence: medium

Minnesota adopts the 2018 IRC with Minnesota amendments as the Minnesota Residential Code (Minn. Rules ch. 1309). No Minnesota amendment to R310.2.1 or R310.2.2 is known. DLI is adopting the 2024 IRC as the next edition; see the 2024 IRC note.

About the Minnesota Residential Code

Citation under review. R310.2.1 and R310.2.2 values and the R312.2.1 triggers (sill under 24 in. above the floor, more than 72 in. above grade) are from the verifier's knowledge of the 2018 IRC and are well established. Confirm the R310.2.1 exception wording ('grade-floor or below-grade'), which this drill does not depend on, and the 2024 section numbers (reported R319.2.1 and R319.2.2).

Why the other choices are wrong

  • The sill is too high; a bedroom window sill may be no more than 42 in. above the floor. The limit in R310.2.2 is 44 in., measured from the finished floor to the bottom of the clear opening. At 43 in., this sill is within it.
  • The opening is too narrow; an emergency escape window must be at least 24 in. wide. The 24 in. minimum in R310.2.1 is for net clear height. The minimum net clear width is 20 in., and this window gives 22.3 in.
  • The window needs a window opening control device because the sill is so high. Window fall protection under R312.2 applies to operable windows whose sill is less than 24 in. above the floor and more than 72 in. above the grade outside. A 43 in. sill on the main floor does not trigger it.
Safety hazardLevel 2 · Journeyman#egress#emergency escape#window#casement#bedroom#calibration

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