No, you do not need an air gap with spray foam insulation. Unlike other types of insulation materials, spray foam is applied directly to the ceiling of the attic, not to the flooring. Here are some reasons why an air gap isn’t necessary with spray foam insulation:
Spray foam insulation is an air barrier and vapor retarder- Spray foam insulation seals all the leaks and gaps in the attic, which means that there’s no need to create an air gap to promote ventilation. The insulation is airtight and doesn’t let outside air or moisture into the attic.
Spray foam insulation prevents heat gain and loss- Spray foam insulation performs well in preventing heat loss and gain through conduction, convection, and radiation. Since it’s applied directly on the ceiling of the attic, it’s a more effective insulator than other types of insulation materials.
Lack of ventilation in the attic- Since there’s no air gap when using spray foam insulation, there’s no need for ventilation in the attic. Ventilation is only necessary when there’s a need to circulate air in and out of the attic to control moisture and temperature. With spray foam insulation, moisture and temperature are already taken care of.
In conclusion, when using spray foam insulation, there’s no need for an air gap. The insulation covers the entire area, eliminating the need for ventilation and improving the energy efficiency of your home.