Generally speaking

Generally speaking, more attic ventilation is better than less, especially if the home’s building envelope at the thermal boundary is well air sealed so that any excess attic ventilation is not able to draw conditioned air from the home’s living space. When we see a home with a problem related to attic ventilation, it is usually from too little. We have found structures built without the building code’s minimum ventilation requirements. We have also found attics where a home improvement project was done in a manner that blocked, and choked off, the otherwise adequate lower ventilation structures.