Troubleshooting a Soffit Vent Exhaust Troubleshooting a Soffit Vent Exhaust

A soffit vent exhaust system is, at its core, a series of openings in the roof, eaves, and walls of a house that are supposed to regulate the air temperature in an attic or roof-space. By letting air flow through these spaces, the air temperature within the walls begins to equalize with the air temperature on the outside.

The result is that little or no condensation forms from the water vapor in the air, and the attic is somewhat protected from water, ice, and mold damage. If encountering a problem with a soffit vent, read through the list of common problems and their solutions below. With any luck, they will help fix the vent and keep the house from being damaged.

The Soffit Exhaust Vent Appears Clear from the Outside, but There Is Little Air Flow Into the Attic

Whenever a soffit exhaust vent seems to not be working, check for exterior blockage. Leaves, sticks, or dirt can block vents. When the exterior of the vents appears clear, the problem is usually internal. Although many soffit vents may look to be clear of obstruction from the outside, inside, insulation or structural features such as wood beams may be blocking airflow.

Some builders, especially in northern climates, will stuff soffit vents with insulation deliberately in an attempt to keep heat from escaping during the cold months of the year. An easy and inexpensive solution to this problem is to install foam roof baffles. These baffles gently push insulation back and away from vents to allow air to flow past. The insulation can stay in the attic and the air can resume flowing, it’s a win-win situation.

The Soffit Vents Are Clear, but the Attic Air Seems Stagnant

The problem here may be one of balance. Many builders install plenty of air intake vents and not enough exhaust vents or vice versa. The result is that the air has no place to escape and not only becomes trapped within the attic area, but also keeps fresh air from getting in.

Imagine opening the door of a house to let air in on a hot summer day. Now imagine that at the opposite end of the house another door was opened. The result would be a sort of tunnel effect that would allow air to flow through the house. Rather than having to push its way in against the old air that is already within, the old air will flow out one side and the new air in the other.

Similarly, in an attic with too many intake vents on the soffits you may need to add some ridge vents for exhaust. The only way to be sure this is the problem, is to count the number of intakes and match them to the number of exhaust vents. If necessary, install more exhaust vents. If unsure about how to determine how many vents an attic should have, then keep reading.

The Attic Feels Extraordinarily Hot

The problem may be that there are simply not enough total vents in the attic to properly ventilate the space. The recommended amount of venting is 1 square foot of venting for every 150 square feet of attic space. The resulting number must be divided by two, half for intake vents and the other half for exhaust vents. So, an attic with 300 square feet of space would need two vents: one intake and one exhaust.

That being said, it is always better to err on the side of caution; there is no such thing as too much venting. One other thing to keep in mind is that just because an attic is hot does not necessarily mean it is improperly vented. Despite even the best of efforts, there are some things that will cause high temperatures in an attic regardless of the amount of soffit vents running to and from it.

Things like shingle color (dark shingles absorb more heat) and the orientation of the primary roof plane are factors that dramatically affect the temperature within an attic. As long as the attic is not over 20 degrees hotter or colder than the outside air, the soffit is most likely working properly.

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