Does skirting around the home need vents?

Generally yes, unless the crawl space is designed as a sealed, unvented space. IRC-based codes, as adopted in Bullhead City, Arizona, require vent openings with at least 1 square foot of net area per 150 square feet of under-floor area, which can drop to 1 square foot per 1,500 square feet when the ground is covered with a Class I vapor retarder. The same code requires an access opening of 18 by 24 inches through a floor or 16 by 24 inches through a wall. HUD's standards add that skirted manufactured homes need a ground vapor retarder in non-arid areas. Skirting should be weather-resistant, leave a way in for service, and not trap water against the home.

Check your local rule. This varies by state, county or city. Your permitting office has the final word; the official lookup pages below show you who that is.

Sources

• Residential Code (2018 IRC) AttachmentCity of Bullhead City, AZ
• 24 CFR Part 3285, Model Manufactured Home Installation Standards (2020 edition)U.S. Government Publishing Office (HUD regulation)