You can use a thermometer and a hygrometer to measure the temperature and humidity in your attic. Ideally, the temperature and humidity in your attic should be close to the outside air. If your attic is too hot or too humid, it means that your attic is not properly ventilated and needs more airflow.
A roofing contractor is the go to person when it comes to the overall health of your roof. They specialize in assessing the physical condition of various components such as vents, soffits, and ridge caps. If you're uncertain about how many vents you need or what size is best, they've got you covered.
This shortcut conveniently calculates the 2021 International Residential Building Code MINIMUM (IRC Section R806 – Roof Ventilation 1) which states, in part, 1 square foot of Net Free Area for every 150 square feet of vented space (attic floor area) with the attic defined as length x width floor of the attic).
The net free ventilating area shall not be less than 1/150 of the area of the space ventilated, with 50 percent of the required ventilating area provided by ventilators located in the upper portion of the space to be ventilated at least 3 feet (914 mm) above eave or cornice vents with the balance of the required ...
It is absolutely possible the ventilation system on your roof is excessive. Maybe your home is older and prior ventilation was installed by a homeowner, or incorrect vent sizes were used in an older roof layout. Too much ventilation can negatively influence the attic's and home's insulation as well.
Excessive Heat in the Attic
With poor ventilation in house, the hot air concentrated at your attic's highest points stays trapped. This, in turn, can lead to uneven roof temperatures (ice dams), an overtaxed HVAC (higher energy bills), and other costly headaches.
Recommend a Roofing Contractor
Even if the HVAC contractor identifies a problem with the attic ventilation system, it may be best to allow the roofing contractor to step in.
To determine how much ventilation your attic needs, divide the total square footage by 300. For example, if your attic is 40 feet by 60 feet, its total area is 2,400 feet. This means that your attic will need eight feet of ventilation, with half using intake vents and the other half using exhaust ventilation.
If we breathe in and the air is fresh, and free of unpleasant smells, irritants, pollutants or allergens, then we can fairly determine (at least on a larger scale) if the house is getting its fair share of fresh, outside air and preventing inside air from becoming stale and damp.
Soffit vents can become blocked due to various reasons: Accumulation of leaves, dirt, or debris can hinder proper airflow through the vents. Improper installation of insulation, baffles, or attic floor coverings can obstruct ventilation.
Attic fans range differently depending on what kind of the Attic fan you are installing, you can expect to pay between $350 to $1,000 installed. The pricing varies based on the type of Attic fan, the sizing requirements, and the motor type.
Attic professionals inspect your rafters, ceiling joists, and insulation and thoroughly check the area for specific problems like moisture cumulation or mold growth. They also typically inspect vents and openings to ensure air passes in and out of your vents easily.
Adequate ventilation is key, and one of the first things looked at in an attic inspection. Cooper says attics must be properly ventilated so the roof and attic can “breathe.” “Signs of poor ventilation include, mold, rusted nails and condensation — typically in the winter — on sheathing,” Cooper says.
Who to Call for an Attic Inspection. An experienced, licensed home inspector will know exactly what they're looking for and identify any problems, where they might be coming from, and an action plan for you to follow.
Ridge Vents are popular. They work well because they provide even ventilation across the whole attic. They are installed along the roof's peak, allowing hot air to escape naturally without the need for power.
Effects of Poor ventilation can lead to a buildup of indoor air pollutants, triggering respiratory problems and allergies. Additionally, it hampers cognitive function, as increased carbon dioxide levels affect concentration and decision-making.
The first sign of poor attic ventilation is when your upstairs rooms are uncomfortably hot. Without proper attic ventilation, the hot air gets trapped with no fresh air being pulled in. This heat radiates down into the living spaces below to the point where it won't be cool enough to be in them until the sun goes down.
When calculating how much attic ventilation you need, your roofer will either use the 1/150 or 1/300 rule. The one they use determines how much Net Free Ventilation Area (open area for air to pass through) you'll need for every 150 or 300 square feet of attic space.
A poorly ventilated attic can cause attic mold and mildew, ice damming, temperature fluctuations inside your home, and deterioration. Keeping it in tip-top shape is important.