How to Calculate Balanced Attic Ventilation | Intake + Exhaust Explained

How to Calculate Balanced Attic Ventilation | Intake + Exhaust Explained Proper attic ventilation protects your roofing system, reduces heat and moisture damage, and helps extend the life of your shingles. In this video, we break down the basic principles of planning a balanced attic ventilation system using real-world examples and simple calculations. We cover: ✔ Calculating attic square footage ✔ Understanding NFVA (Net Free Ventilation Area) ✔ Using the 1:300 rule for balanced airflow ✔ Splitting intake and exhaust properly ✔ Choosing ventilation products based on NFVA ratings ✔ Why you should never mix exhaust vent types ✔ Common mistakes that cause short-circuiting 🔢 EXAMPLE CALCULATION FROM THE VIDEO Attic Size: 30 ft × 40 ft = 1,200 sq ft Minimum NFVA (1:300 rule): 4 sq ft / 576 sq in Balanced System: 288 sq in intake 288 sq in exhaust Example product conversions shown using: Master Flow Under-Eave Intake Vents (50 sq in each) Cobra Intake Pro (9 sq in/ft) Cobra Ridge Vent (18 sq in/ft) Master Flow Slant-Back Louvers (60 sq in each) ⚠ IMPORTANT NOTE Local codes may require more ventilation than the 1:300 rule—some use 1:150. Always check with your local building department and roofing contractor. 🏠 Why Balanced Ventilation Matters A balanced system prevents: Moisture buildup 🚫 Mold & wood rot 🚫 Ice dams (cold climates) ❄️ Heat stress on shingles ☀️ Imbalance may cause short-circuiting, where exhaust vents pull air from other exhaust vents instead of soffits—making the system ineffective. 🔹 Need help calculating ventilation for your roof? Use the online ventilation calculator: Consult your roofing manufacturer or contractor for specific requirements. 📍 Subscribe for more roofing education Welcome to Steel Country Home Restorations, your trusted roofing and home improvement team serving San Antonio, Cibolo, Boerne, and surrounding Texas areas. 🏠 We specialize in: ✅ Roof Replacements – residential & commercial ✅ Roof Inspections & Storm Damage Repairs ✅ Gutter Installation & Home Restoration Projects ✅ Insurance Claim Assistance ✅ Drone Documentation & Professional Assessments At Steel Country, we deliver five-star service, honest workmanship, and Texas-strong craftsmanship. Every project is handled with integrity, precision, and care — because your home deserves nothing less. 📍 Service Areas: San Antonio • Cibolo • Boerne • New Braunfels 📞 Contact us today for a free roof inspection or estimate. 👉 Subscribe and follow our page for project updates, roofing tips, and before-and-after videos! Steel Country Home Restorations — “Five-Star Service. Five-Star Results.” 💯