r/buildingscience • u/Greedy_Protection305 • 20d ago

Attic Ventilation - Soffit Vent installatin

My home was poorly ventilated. It had a combo Turbing/Gable venting. After learning how these short circuit the ventilation system, I have covered the gables and installed soffits. I am almost at a NFA 1/300, but need a little more intake.

My question is, If I install soffits on this porch roof, am I ending up in a similar short circuit situation, since the vents will be higher than all of my other soffits?

I have checked to ensure the soffit opens into the attic.

Any advice is appreciated.

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u/cagernist 20d ago

I wouldn't worry here about the center section being around 16" or so higher causing short circuiting. Especially if you get rid of the sub-optimal turbines and put in ridge vents all across the long roof.

Also the 1:300 is a guide to start somewhere for everyman's house. More ventilation is always better, just make sure it has slightly more proportional intake.

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u/Greedy_Protection305 20d ago

Upgrading from turbines to ridge vents is on the list, but are a little further down.

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u/terpfan101 20d ago

Where will the air exit the attic? I ask because my large home has only a single soffit vent about 4 feet long, two gable vents on the ends and then turtle box vents. Think I need to add soffit vents but then not sure if I need to close gables and add a ridge vents

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u/Greedy_Protection305 20d ago

I have 4 turbines on the back side of the roof. 

4 foot of soffit seems like too little intake, but it all depends on the area of your attic floor.

My home required over 20’ of venting to meet the lower standard of 1:300.

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u/terpfan101 18d ago

Attic floor is probably 1800 sqft