To figure the number of roof vents needed use the following correct:
1 square foot for every 150 square foot of attic
1 square foot for every 300 square foot of attic with soffit vents.
But what if there’s a thermostatically controlled powered vent? How many square feet will a powered vent cover?
Pictures here are on a house that’s about 1000 square feet, soffit vents, and one powered vent…enough ventilation?