An enclosed parking garage is a parking structure that does not have enough exterior wall openings to qualify as an open parking garage, so it must be mechanically ventilated and is subject to stricter fire protection requirements.
Building codes distinguish garages by how well they ventilate naturally. Under International Building Code Section 406.5.2, an open parking garage must have openings on its exterior walls totaling at least 20 percent of the total perimeter wall area of each tier, with the openings distributed over at least 40 percent of the perimeter length. A garage that falls short is enclosed.
What changes when a garage is enclosed
- Mechanical ventilation is required to control vehicle exhaust under International Mechanical Code Section 404. See demand-controlled ventilation.
- Automatic sprinklers are required for enclosed parking garages under IBC 903.2.10, based on fire area and on location, such as beneath other occupancies.
- Lighting and energy loads rise, since daylight no longer reaches most of the floor.
The Parkonomics view
Whether a garage is open or enclosed is one of the most expensive decisions in parking design, and it is often made by accident through facade choices. Screening, louvers and architectural cladding can push an open garage over the line. Check the opening calculations before the facade design is locked.
Related terms: International Code Council, Demand-Controlled Ventilation, Air Outlet, Smoke Barrier, Mechanical-Access Parking Garage
Further reading: The Evolution of U.S. Parking Structures in 2026