Lack of soffit vents with the use of ridge vents on a 1941 home

Question

[Home is in Georgia]

I made the mistake of installing ridge vents on my home last year without any soffit vents. I have since learned that doing so will actually cause the air to be drawn from all accessible places, including a leaky 1941 ceiling.

I realize what I should have done was to install drip edge venting but am unable to do so retroactively (I think). Since I have learned of this mistake, I have air sealed the ceiling. The attic currently has 4 gable vents located on all 4 walls of the house but they are located at the peaks which to my understanding, limits the air flow across the bottom of the decking and thus preventing proper cooling.

My question is this; I have an enclosed porch which has a ceiling that is a part of the attic. It has no insulation over it and I was wondering about the benefits of installing a large vent in the ceiling to allow for more air flow to the ridge vents. I realize that this will still not provide the same benefits as soffit vents and baffles in cooling but I figured it may reduce the amount of air being drawn from inside the house and also allow for less heat buildup in the attic.

Your insights are greatly appreciated.

Answer 1

Adding a vent to the ceiling of your porch would only be beneficial if you open up any exterior windows and doors leading into the porch. Then you'd have air flow from outside through the porch and up into the attic. The only time it would be useful would be in the summer when you'd be replacing 130 degree air with 85 degree air. so yes, it would benefit in the summer. If you opened the doors leading to the porch from your living space in the summer, you'd be sucking AC air from the living space to the porch into the attic.... not too efficient.

Answer 2

My 1929 Craftsman house has similar design... 2 gable vents but no soffit vents, and no possibility of installing them. Air sealing your ceiling was a great step, but look into "deck vents" marketed by Air Vent and other brands.

Deck vents are a shallow wedge that goes under the shingles, covering a 1" (2-3cm) wide slot to allow air in or out. Putting them low on the roof with a ridge vent at the top will get airflow across nearly the entire roof deck, much like soffit vents, and remove a lot of heat & moisture from your attic.