// CODE SNIPPET
1202.4 Under-Floor Ventilation
JUMP TO FULL CODE CHAPTER
The space between the bottom of the floor joists and the earth under any building except spaces occupied by basements or cellars shall be provided with ventilation in accordance with Section 1202.4.1, 1202.4.2 or 1202.4.3.
Ventilation openings through foundation walls shall be provided. The openings shall be placed so as to provide cross ventilation of the under-floor space. The net area of ventilation openings shall be in accordance with Section 1202.4.1.1 or 1202.4.1.2. Ventilation openings shall be covered for their height and width with any of the following materials, provided that the least dimension of the covering shall be not greater than 1/4 inch (6.4 mm):
- Perforated sheet metal plates not less than 0.070 inch (1.8 mm) thick.
- Expanded sheet metal plates not less than 0.047 inch (1.2 mm) thick.
- Cast-iron grilles or gratings.
- Extruded load-bearing vents.
- Hardware cloth of 0.035-inch (0.89 mm) wire or heavier.
- Corrosion-resistant wire mesh, with the least dimension not greater than 1/8 inch (3.2 mm).
- Operable louvres, where ventilation is provided in accordance with Section 1202.4.1.2.
The net area of ventilation openings for crawl spaces with uncovered earth floors shall be not less than 1 square foot for each 150 square feet (0.67 m2 for each 100 m2) of crawl space area.
The net area of ventilation openings for crawl spaces with the ground surface covered with a Class I vapor retarder shall be not less than 1 square foot for each 1,500 square feet (0.67 m2 for each 1000 m2) of crawl space area.
In extremely cold climates, where a ventilation opening will cause a detrimental loss of energy, ventilation openings to the interior of the structure shall be provided.
Mechanical ventilation shall be provided to crawl spaces where the ground surface is covered with a Class I vapor retarder. Ventilation shall be in accordance with Section 1202.4.3.1 or 1202.4.3.2.
Continuously operated mechanical ventilation shall be provided at a rate of 1.0 cubic foot per minute (cfm) for each 50 square feet (1.02 L/s for each 10 m2) of crawl space ground surface area and the ground surface shall be covered with a Class I vapor retarder.
The crawl space shall be conditioned in accordance with the International Mechanical Code and the walls of the crawl space shall be insulated in accordance with the International Energy Conservation Code.
For buildings in flood hazard areas as established in Section 1612.3, the openings for under-floor ventilation shall be deemed as meeting the flood opening requirements of ASCE 24 provided that the ventilation openings are designed and installed in accordance with ASCE 24.
Related Code Sections
1202.4 Interior Environment, Under-Floor Ventilation
ventilation of the under-floor space. The net area of ventilation openings shall be in accordance with Section 1202.4.1.1 or 1202.4.1.2. Ventilation openings ...
Building Code 2018 of Illinois > 12 Interior Environment > 1202 Ventilation > 1202.4 Under-Floor Ventilation
2308.4.8 Wood, Under-Floor Ventilation
For under-floor ventilation, see Section 1202.4 ...
Building Code 2018 of Illinois > 23 Wood > 2308 Conventional Light-Frame Construction > 2308.4 Floor Framing > 2308.4.8 Under-Floor Ventilation
2304.12.7 Wood, Under-Floor Ventilation (Crawl Space)
For under-floor ventilation (crawl space), see Section 1202.4 ...
Building Code 2018 of Illinois > 23 Wood > 2304 General Construction Requirements > 2304.12 Protection Against Decay and Termites > 2304.12.7 Under-Floor Ventilation (Crawl Space)
1202.4.3 Interior Environment, Mechanical Ventilation
Mechanical ventilation shall be provided to crawl spaces where the ground surface is covered with a Class I vapor retarder. Ventilation shall ...
Building Code 2018 of Illinois > 12 Interior Environment > 1202 Ventilation > 1202.4 Under-Floor Ventilation > 1202.4.3 Mechanical Ventilation
1202.4.2 Interior Environment, Ventilation in Cold Climates
In extremely cold climates, where a ventilation opening will cause a detrimental loss of energy, ventilation openings to the interior ...
Building Code 2018 of Illinois > 12 Interior Environment > 1202 Ventilation > 1202.4 Under-Floor Ventilation > 1202.4.2 Ventilation in Cold Climates