🏠 Your roof assembly – Part 5: Ventilation

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





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