How roofing ventilation fights moldy attics

Welcome back to our weekly series on roofing anatomy. We’re breaking down the different parts of your roof step by step so you can make informed decisions about your roof and keep your home safe!

This week, we’re covering an important part of what covers your home: roofing ventilation.

Roofing ventilation is an important part of your roofing system, working together with the rest of your roof to accomplish several important goals:

  • Heat and water vapor from your home rises into your attic. Without ventilation, that moisture leads to mold and water damage.

  • Your attic can get too hot if not properly vented, which “cooks” your shingles from the inside.

  • If your attic is hot, your air conditioner needs to work extra hard to keep your home cool.

  • Proper ventilation helps prevent ice dams, which are very common here in Moscow and Pullman!

Let’s get started.

Why does roofing ventilation matter?

An improperly vented roof can lead to many problems. Not only do you have the immediate problems of condensation and a higher heating / cooling bill, you have the longer term problem of premature roof failure.

Above: This roof looks normal from the outside, but when we inspected the attic we found out that it was left sealed shut. This arrow indicated where the attic should be open for ventilation.

Above: This roof looks normal from the outside, but when we inspected the attic we found out that it was left sealed shut. This arrow indicated where the attic should be open for ventilation.

The photo above shows the underside of a roof that was recently re-roofed by another local company. Our remodeling company, Ealy Construction, was on site for another project and noticed something odd in the roof: The ridge vent was improperly installed and completely sealed shut!

You see that grey fabric peeking through the hole? That hole is supposed to be cut open when the roof is completed, allowing air to flow through it and out of a ridge vent on the top of a roof.

Because of this careless mistake the attic had already started to mold only a few weeks!


So why would a home with a new, watertight roof still end up with a moldy attic? The culprit here is that hot air and moisture from inside the home wasn’t able to escape.

Because your heating and air conditioning systems bring in air from outside, your home has what’s called “positive pressure” and pushes air outwards.

That air carries water vapor as it’s driven outward through your walls and roof. Without proper ventilation, this vapor can be trapped. When trapped in your home it leads to mold.

How does roofing ventilation work?


Your roof ventilation brings cool, fresh air in down low and carries hot, moist air out the top.

This helps maintain proper moisture levels and keeps your indoor temperature comfortable.

What type of ventilation does my home have?


On modern homes, you’ll typically see soffit vents and ridge vents.

The left photo shows a soffit vent, which brings in cool, fresh air. The photo on the right shows a ridge vent, which lets hot air and moisture escape.


Older homes typically have gable vents (left) for intake and attic vents (right) for exits.

If you’re experiencing discomfort in your home, you may need to update your ventilation. give us a call and we’ll talk through your options.

How we can help you keep your roof properly vented.

Proper roofing ventilation is an important part of the roof system. When we inspect your roof we consider whether you would be better off with the existing system or upgraded ventilation.

When we reroof a house, we typically match the existing style and type of ventilation unless there is an issue or concern. It can be costly to retrofit roof ventilation, so we try to avoid it when possible.

However, for the health of your house and your comfort, updating your ventilation ought to be considered.

If you think your roof might be reaching the end of its life, you can schedule a free inspection in under 60 seconds through our site here.

Or, give us a call at (208) 301-6173 for a quick chat about your situation. We’re always happy to talk with homeowners in Moscow & Pullman!

Nethaniel Ealy