What is the code requirement for the height and width of an access opening to the crawl space under a house?
Tuesday, December 11, 2018
The crawl space must have an entry opening that is a minimum of 16-inches high by 24-inches wide if it is at an exterior wall, according to the International Residential Code (IRC) and the Residential Edition of the Florida Building Code (FBC R408.4). An access opening from the floor above must be 18-inches by 24-inches.
When the access is below grade, a 16-inch deep by 24-inch wide clear area (well) in front of the opening must be provided.
If there is an access panel, it has to be removable without using any special tools or damaging it. The loose access panels shown at the top of the page would certainly meet the easy-removal standard, but they do not seal the opening against critters getting under the house and tearing up the floor insulation. Plus, the hose faucet reduces the clear opening width to less than 24-inches and the height is only 12-inches.
The dimension from the dirt to the bottom of the floor joists needs to be a minimum of 18-inches, with at least of 12-inches under any beams. While it is possible for a compact person to crawl through a 12-inch space under a beam, it becomes difficult lift your head to view upwards or twist around readily in a shorter height than 18-inches in the open areas under the floor joists.
Also, if there is any mechanical equipment under the home, such as an air handler, then the opening must be big enough to remove it for replacement. And when part of the opening is below grade, the entry well must have a 16-inch by 24-inch footprint.
Then again, once in while the access panel is just plain ridiculous—like the appoximately 12-inch square opening we were directed for for access under a home in Gainesville, with an active electrical disconnect box mounted on the door.
To learn more, see our blog posts What does a home inspector look for in the crawl space under a home? and Should I buy a house with a crawl space?
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To learn more about exterior walls and structures, see these other blog posts:
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