Why ventilation in your attic space matters

We are always excited to see at least two forms of air flow to an attic space because this means there is air movement and a lesser chance for moisture issues. When an attic space is unfinished, we can have a better perspective of the conditions, but sometimes an attic can be finished off into living space. This obviously blocks our visual ability to observe the conditions of the attic, but we can still find clues based on what we see from the exterior.

Moss and lichen buildup along roofing materials, especially on the Northern side of a home, is likely to be found when moisture has no way to escape or dry out. Tree coverage over the structure can also affect their growth, but that’s an outside factor from what we are focusing on. Moisture can build up under the edges of shingles or along the connecting point of where a roof meets a wall.

Some of the key components we are looking for in an attic ventilation system are the entrance and exit points of the air flow. These tend to work in conjunction, such as soffit vents with ridge vents, a gable vent with a powered fan or a window along with turbine ventilators. Windows and gable vents are sometimes used on their own, but depending on the square footage of the space, these may or may not be enough.

The formation of ice dams at the eaves is a good indicator for a lack of ventilation. In this circumstance, the attic is too warm, which allows snow to melt off the upper portion of the roof. As the lower portion, or the eaves, is cooler, the snow does not melt as quickly and is more likely to refreeze instead of melting off the roof’s edge. As ice starts to form, the frozen water can start to seep into any crevices it can (ie. under the shingles and sheathing. This is what leads to water ingress between the structure’s coverings.

We had this happen to us in a previous home. The attic had soffit channels to prevent the blown in insulation from blocking the vents, and there were two windows on either side of the attic. Aside from a previous mold problem, it seemed like this should have been sufficient ventilation for this unfinished space. However, upon further review of the exterior, we found that the attic did not actually have any soffit vents installed. This is likely how the ice dam managed to develop and how we ended up with leaks in our ceilings and between the walls along that side of the structure.

Proper ventilation is a key factor in the functionality of the roofing system. Without steady air flow, moisture has a higher chance of causing problems. Let Short Notice Inspections be your guide to who you should call based on our findings.