Attic Ventilation: More Than Just Air Circulation

Attic ventilation

How can you find soggy attic insulation if there’s no roof leak in sight? Soggy insulation is not only possible, it’s probable, in a house with poor ventilation.

Houses are complex, sophisticated things with countless interrelated systems. And attic ventilation is one of many that must function on its own as well as in concert with everything else. Wondering how many problems poor ventilation can cause? Read on and find out.

Ice Dams and Frost

Southern regions don’t usually have to worry about ice dams. But for everyone else, icicles dripping off the roof edge is a sign of real wintertime trouble. Frost inside the attic is another clue that the ventilation isn’t working properly.

When warm air gets trapped under the roof decking, snow and ice on the shingles begin to melt. Then when the weather snaps colder at sunset, the melting water freezes again. Attic ventilation lets warm air trapped inside the attic escape, regulating the attic temperature. With too few vents or vents that don’t work properly, warm air gets trapped and water can wreak havoc.

Mold and Mildew

Mold is responsible for allergy flare-ups and more serious health conditions. When mold is found in the attic, everyone in the house may suffer. And the dangerous black mold isn’t as easy to identify as the name implies. There are thousands upon thousands of species.

In fact, homes produce a lot of condensation from cooking, showering and just breathing. The more people in the house, the more condensation is produced. And without proper attic vents, it has nowhere to go besides into the walls and up to the attic where trapped heat gives it the perfect environment for growth.

Widespread or Concentrated Structural Rot

Wood and water don’t mix, at least not very well for very long. A home’s structural components are wood, and so is the attic roof decking. And over time, moisture can break down the very home systems that hold it together.

Without proper attic ventilation, a high moisture level can stay reasonably constant. It’s that chronic dampness that breaks down wood fibers, which can lead to major structural repairs in the long run.

Attic ventilation

Roofing damage often begins at vulnerable spots, such as unsealed fastener holes.

Roofing Damage and Deterioration

As if the decking wasn’t enough, poor ventilation can also damage roofing materials. Some roofing, such as slate and rubber, might be immune to ventilation-related damage, at least for a while. But asphalt shingles (by far the most common roofing in America), isn’t as impervious. And some metal roofs are susceptible to both heat and moisture.

With improper or inferior attic ventilation, excess heat from inside the house can only travel as high as the roof deck. Combine that with heat from the sun, and you’ve got roofing and sheathing that are cooked from above as well as underneath. Bring water into the mix, and it’s a terrible recipe.

It might be hard to imagine how many home defects can trace back to a simple attic vent or lack thereof. Just because a house has vents at the ridge, on the roof deck, or tucked into soffits doesn’t mean that they’re adequate.

When you spot a mysterious issue and can’t find the source, think out in all directions about the other systems that affect it. Poor ventilation can mimic a roof leak, create mold colonies, and even wear down a heat pump before its time. Fortunately, it’s also one of the easiest defects to correct.

Home inspectors have the training to spot a host of material defects and their causes. And ICA School has one of the most comprehensive home inspection training courses available. What makes our program better? Get a free course demo and find out firsthand.

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