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Why should I ventilate my attic?

Proper attic ventilation works to decrease heat and moisture within your attic space. Why should you care about heat and moisture? Attic heat and moisture can lead to potential damage to your home and any items that are housed in your attic including mechanical and electrical equipment.

Ventilation is key in reducing your heat and moisture and the potential negative effects it can have on your home. The purpose of attic ventilation is to exchange air in order to prevent heat and moisture buildup. Ventilation is simply bringing in fresh outside air from intake points in your attic space and exhausting out of the highest point of the attic. However, there are a few keys to properly ventilating your attic.

ATMOX House Graphic with ATMOX Attic Fans

Effective ventilation begins with sealing off your living space from your attic space. Your house needs a barrier between your living space and your attic space. The reason for this barrier is to prevent unwanted moisture and heat from seeping into your attic. Therefore, proper insulation along with sealing cracks and gaps help reduce the amount of moisture and heat from entering the attic from the living space. 

Attic Moisture

Photo of condensation in an attic

Moisture in your attic can lead to condensation and in turn mold and wood rot. Attic moisture issues generally start from moisture generated in your home. For example, your daily activities such as cooking, showering and laundry all create moisture. All this warm moisture rises and finds its way into your attic space through open gaps and cracks. 

Bathroom and kitchen exhaust fans are highly effective at removing moisture. However, these fans are sometimes installed improperly with the fans exhausting into the attic. These fans should exhaust through a roof cap directly to the outside. If these fans are installed improperly by venting into your attic, they could cause issues with moisture in your attic space and potentially costly damage.

Any moisture that seeps into your attic can get trapped without proper ventilation. If the attic is cold, the air can’t hold a lot of moisture, and the moisture will quickly start to condense. This condensation can lead to mold and wood rot, if not removed. Reducing this moisture through ventilation will help you prevent potential damage.

Attic Heat

Sun Melted Shingles

Heat in the attic may not be visible but you can certainly feel it! On a hot summer day your attic can reach temperatures as high as 150 degrees. This extreme heat is not energy efficient. Additionally, it can also lead to issues with your home.

This excessive heat in an attic also heats the home’s structure. This heat can affect the structure of your home and your roof. It can also increase the temperature of your living space. This can create a heavy workload on your HVAC system as it tries to keep up with the increasing heat. As you know, this increase in AC usage increases your energy consumption and cost. This excessive heat increases the potential for roof damage as well. Asphalt shingles will deteriorate in extreme heat generated inside the home as well as the heat from the sun.

Active vs. Passive Attic Ventilation

Your attic needs proper ventilation with fresh outside air to improve air quality, energy efficiency and to protect your home from negative effects of moisture and excessive heat. There are two types of attic ventilation: active and passive.

Passive Attic Ventilation

Passive ventilation is open intake and exhaust points with no mechanical assistance to increase air circulation or air exchange. This type of ventilation requires a great number of soffit openings and an extensive ridge vent. Furthermore, It is important to ensure the soffits are open and insulation is not blocking the openings. This sometimes occurs during installation. So, check your soffits to ensure the insulation is not blocking the openings and pulling air from your living space. Likewise, a ridge vent alone does not always turn over the air at a fast enough rate to reduce heat. In some roof styles the ridge vent is not long enough to provide a large enough exhaust point to exchange the air quickly enough to be effective.

Although it may seem like a simple energy efficient option, it may still not be enough ventilation to effectively turn over the air quickly enough to reduce moisture and heat.

Installing soffits on a house for attic ventilation

Active Attic Ventilation

Active ventilation is the process of assisting air movement from an intake point, usually soffits or gables, and exhausting out at the highest point of the attic. Therefore, mechanical assistance increases the rate in which air is exchanged. This increase in air movement is important in effectively turning over the air quickly to reduce heat and moisture buildup.

ATMOX Pics of Attic Fans on Roof

Distributed Airflow for Proper Ventilation

ATMOX example of an attic ridge vent exhaust fan layout

It is important to ensure that your attic fan is not overpowered. The best option for your attic is to spread several ATMOX fans across the space to keep from pulling air from the living space and ensure a balanced airflow. Furthermore, distributed airflow is important to achieve proper ventilation and reach all areas of the attic to prevent moisture and heat buildup in the space. This is especially critical in addressing attic moisture as those problems often arise in lower levels of the attic or only one side of the house.

Smoke Test Comparison

Sometimes it is difficult to appreciate differences in attic ventilation as you cannot easily see it.

This video demonstrates the comparison of passive ventilation with soffits and ridge vent versus active ventilation with ATMOX controller and fans. 

This home has open soffit vents around the perimeter and a ridge vent at the peak. The left side shows passive ventilation using blue smoke. The right side with green smoke is active ventilation using ATMOX fans installed from within the attic underneath the ridge vent.

The difference in the dissipation of the smoke is significant. As you can see, the rate of the turnover of air flow is much higher with ATMOX fans than just passive ventilation.

This simulation demonstrates how buildup of heat or moisture can occur in your attic with only passive ventilation.

Active Ventilation with ATMOX Fans

Regardless of whether you are tackling a heat or moisture issue in your attic, the ATMOX attic fans will get the air moving at the right times to exchange the air and improve conditions. ATMOX attic fans come in a wide variety of styles and mounting options to fit the needs of your attic.

Post Author: ATMOX TOM