Minimum Attic Ventilation Requirements

The federal housing authority fha and the urban development hud have established minimum requirements for attic ventilation.

Minimum attic ventilation requirements.

Ventilation openings shall have a least dimension of 1 16 inch 1 6 mm minimum and 1 4 inch 6 4 mm maximum. Hence you would need two square feet 600 300 of attic ventilation. To prevent excessive heat buildup in the attic area. As an example in an attic that is 30 feet by 20 feet you would have 600 square feet of floor area.

What are the minimum attic ventilation requirements. Excessive moisture can allow microbial growth and rust. According to their requirements you should have 1 square foot of attic ventilation per 300 sq ft of attic floor space. Nrca guidelines regarding attic ventilation nrca recommends designers provide at least 1 square foot of nfva for every 150 square feet of attic space 1 150 ventilation ratio measured at the attic floor level ceiling.

Measure the length and width of the attic floor space to be ventilated. To prevent excessive moisture buildup on building components.