What is the required CFM for make-up air in a residential dwelling with 2 bedrooms, 3 baths, and a 2-car garage during intermittent operation?

To determine the required airflow in cubic feet per minute (CFM) for make-up air in a residential dwelling, we consider factors such as the size of the space, the number of bedrooms, and any potential exhaust systems. It is generally estimated that a home requires around 0.35 CFM of make-up air per square foot of floor area to ensure a balanced air system and proper ventilation, especially in a situation where kitchens or bathrooms have exhaust fans that could create negative pressure.

In the case of a residential dwelling with 2 bedrooms and 3 baths, the total square footage would typically be calculated based on the general size of the rooms in conjunction with the garage. Assuming a rough estimate includes the usable space:

• Bedrooms: Typically around 200-300 square feet each.

• Bathrooms: Each can range from 50-100 square feet, especially if they are full or half baths.

• Garage: Usually around 400-500 square feet for a 2-car garage.

Calculating the total square footage with averages, one might land around 1,500 square feet for a combined total of this dwelling. Thus, using the 0.35 CFM guideline, the calculation for make-up air would be:

1,500 square