Ventilation is one of the least visible but most important parts of a healthy roof. Get it right and your shingles last longer, your bills drop, and your attic stays dry. Get it wrong and you'll see the opposite.
Why ventilation matters
Your attic needs to breathe. Without airflow, heat and moisture build up — cooking your shingles from underneath, driving up cooling costs in summer, and creating the conditions for mold and ice dams in winter. Good ventilation moves that hot, damp air out.
Intake and exhaust: a balanced system
Proper ventilation isn't just adding vents — it's balancing intake (usually at the soffits and eaves) with exhaust (at or near the ridge). Air enters low and exits high. If intake and exhaust are out of balance, the system won't work well no matter how many vents you have.
How much do you need?
A common guideline is roughly 1 square foot of ventilation for every 150 square feet of attic floor — or 1 per 300 when intake and exhaust are well balanced. In practice it depends on your roof's size and design, which is why it's worth having assessed.
Common vent types
- Ridge vents — run along the peak; a clean, effective exhaust option
- Soffit vents — the intake side, along the eaves
- Box and gable vents — used where ridge and soffit venting isn't enough
Signs your ventilation is off
- An upstairs that's always hotter than the rest of the house
- Moisture, frost, or mold in the attic
- Unusually high energy bills
- Shingles that aged faster than they should have
If any of these sound familiar, have your ventilation checked as part of a roof inspection — it's often an easy fix with a big payoff.