A.Lynn Underwood, an engineer, licensed contractor, and building code official in Norfolk, Va., responds: While the IRC requires certain types of doors for fire protection in attached garages and doesn’t permit them to open into bedrooms, there’s no requirement for a lowered garage floor. BOCA and some of the other previous model codes required a 4-inch step from the garage floor surface up to the house, presumably to prevent spilled gasoline vapors from entering the house and to provide some protection against carbon monoxide. But the IRC never adopted this constraint, mostly because of improvements in automotive design (cars don’t leak very often anymore) and the popularity of single-level post-tensioned slabs.
Still, many building inspectors are like contractors — they never forget a code requirement, even when it changes to eliminate an out-of-date condition. So it’s possible that some inspectors are still enforcing this even though it’s no longer in the code.
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