Calculating Ridge and Soffit Vent Size
by djpolymath in Workshop > Home Improvement
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Calculating Ridge and Soffit Vent Size
![Calculating Ridge and Soffit Vent Size](/proxy/?url=https://content.instructables.com/FXH/6RT7/KKV5T4AZ/FXH6RT7KKV5T4AZ.jpg&filename=Calculating Ridge and Soffit Vent Size)
This video describes calculating ridge vent and soffit vent size.
Guidelines
![2021-02-07 10_15_11-Greenshot capture form.png](/proxy/?url=https://content.instructables.com/F3J/QKHD/KKV5T4OJ/F3JQKHDKKV5T4OJ.png&filename=2021-02-07 10_15_11-Greenshot capture form.png)
1/300 and 1/150 are the recommended guidelines. 1/150 is the most recommended. That means 1sq.ft of vent area per 150sq.ft of attic area.
Calculate Theoretical Area
LengthxWidth=Area of Attic
Attic Area / 150 = Vent area
Calculate Actual Vent Area
![2021-02-06 11_21_54-Movies & TV.png](/proxy/?url=https://content.instructables.com/FSY/NCQ7/KKV5T4OK/FSYNCQ7KKV5T4OK.png&filename=2021-02-06 11_21_54-Movies & TV.png)
Ridge Length x Net Free Area of Ridge vent = Vented Area of Ridge
Vent area of the 2 soffits combined should equal the vented area of the ridge
Calculate Soffit Vent
![2021-02-07 10_14_44-Greenshot capture form.png](/proxy/?url=https://content.instructables.com/FZ6/5UP0/KKV5T4OI/FZ65UP0KKV5T4OI.png&filename=2021-02-07 10_14_44-Greenshot capture form.png)
Soffit vent size
Vented area / number of soffit vents = size of each soffit vent
Soffit vent number
Vented area / size of soffit vents = number of soffit vents