We’ll wrap up this short series on your roof assembly with what you need to know about attic ventilation.
👇 Links to parts 1-4 below
Why it matters: Building code prescribes proper ventilation for your attic in order to provide a way for heat and moisture to escape to the outside.
🔬 Zoom in: Here’s your checklist:
👉 Know how much ventilation you need —> Determine the square footage of the attic and use a vent calculator like this one.
- If you have more than one distinct attic area, each is considered separately for the calculations.
👉 Choose the type of vent you want —> Based on how much air each vent can move.
- Exhaust vents include turbines, ridge vent, static vents and power vents (Click here to read why I don’t like power vents.).
- Intake vents include 4 inch, 6 inch and 8 inch soffit vents, continuous soffit vents, and deck mounted vents like DeckAir
- Gable vents were great for wood shake roofs when the roof itself could breathe a little bit, but tend to be more of a problem for most roofs. We like to block the gable vents and use other ventilation.
👉 Balance the exhaust and intake —> The vent calculator will tell you how much intake you need for each type of exhaust vent.
- The biggest problem we see on existing roofs is NOT having enough intake.
- People tend to add more exhaust than they need —> but it’s better to have more intake than you need.
👉 Don’t mix exhaust —> Only one type of exhaust vent should be used.
- The second biggest problem we see on existing roofs is mixed exhaust —> a power vent installed next to a ridge vent will pull air from the ridge not from the soffit.
👉 Install exhaust vents at the same height —> If an exhaust vent is installed at a lower height, the upper vent will pull from the lower exhaust instead of the soffit.
- This only matters on common attic areas. Distinct attic spaces are treated separately.
✅ For your Smart Homeowner list
- Attic ventilation can be addressed at any time, but it’s easy to fix when getting a re-roof.
- If your insurance policy includes code upgrade coverage, your carrier will often pay for the added cost to bring ventilation to code as part of your re-roof.
Links to your roof assembly series