SOUTH MIAMI Blog

Attic Ventilation - the right choice for your home?

Letting the South Miami heat into your home on purpose seems counterintuitive, which is why many homeowners are skeptical about attic ventilation. However, it is an important topic to consider when thinking about your home’s energy efficiency and there are advantages to both vented and unvented attics. Whether your home would benefit from a vented or unvented attic depends on many factors, like your climate, your roof and your insulation. 

Unvented Attics

Unvented attics do not have any vents and are usually completely air sealed by a barrier-creating insulation like spray foam. All gaps and openings are closed to keep the heat and humidity outside which means that outside air can never get in. As a result, the temperature in your attic is more consistent and you don’t have to worry about weather fluctuations - energy efficiency can be optimized and your attic and home will stay cooler without higher A/C costs. 

Insulation types used in unvented attics, like spray foam insulation, offer optimal protection for your home and not only keep heat and humidity under control but also keep pests and insects out of your attic as it blocks all possible entryways. 

Benefits of an unvented attic:

• Solutions like spray foam insulation provide the best heat and moisture protection and prevent mold and other problems under your roof. 
• The temperature in your attic stays cooler and more consistent.
• Unwanted visitors are kept outside.
• Spray Foam lasts a lifetime so you won’t have to worry about your attic for a while. 

Downsides of unvented attics:

• Insulation solutions like spray foam are more expensive than attic vents.
• Homes are not always built with insulation in place.

Vented Attics

Your insulation reduces temperature fluctuations and helps you save on your energy bills by keeping the Florida heat out of your home. Nevertheless, especially in the Florida climate, warmth and humidity can accumulate in the highest point of your home, the attic, and cause heat and moisture problems if trapped. A vented attic will introduce outside air into your attic and keep the air fluctuating. In the colder months, the incoming air can actually help cool down your attic and home. 

Even though your South Miami home could benefit from vents; overall, vented attics tend to have more benefits for homes in climates with harsh winters where vents can prevent ice damming and other winter problems that are not on a Miami homeowner’s mind. Many homes are built with vented attics so it might be useful to get your attic assessed by a professional to find out about your home’s state. 

Benefits of a vented attic:

• Vents can protect your roof against moisture damage.
• They are relatively inexpensive.
• Your home might already have vents installed.

Downsides of a vented attic:

• The main benefits are ice and snow protection which are unnecessary in Florida.
• Moisture can still accumulate, even with vented attics. 
• The temperature will be closer to the outside temperature which means that you shouldn’t use your attic for storage as things might get exposed to too much of our Florida heat. 

Types of attic ventilation

Passive ventilation

Passive/natural ventilation uses thermal upward forces and air currents to provide air circulation. The hot air that rises is circulated out of the home and fresh air is brought in to push out old air. For this reason, it is particularly useful for homes where the temperature difference between outdoor and indoor is high.  

Passive ventilation methods include

• Ridge vents - one of the most common types of passive vents. They’re installed across the peak of the roof along the entire length and because of this position are best for letting large amounts of hot air out. 
• Off-ridge vents - a smaller, box-shaped version of the ridge vent at the top of the roof. They are great for smaller homes or houses with more uneven roofs / more peaks and valleys.
• Box vents - perfect for more complicated roof designs or if you want ventilation in specific areas of your home. 
• Soffit vents - installed directly under the eaves of your roof, located underneath your overhang. They have small holes that allow cool air for air circulation and come in a long, continuous or short, individual shape. 
• Gable vents - usually installed on the exterior wall of your attic in order to create proper air circulation during extreme climate conditions. They allow air to escape the attic which prevents moisture build-up. 

Active ventilation

Active ventilation provides indoor air circulation through mechanical fans. These types of ventilation are key for areas with high humidity like South Florida that make attics prone to moisture build-up. The air circulation with mechanical fans is more consistent as it doesn’t rely on natural winds. Solar-powered systems are particularly useful since they don’t increase your energy bill but feed off of the Florida sun. 

Active ventilation methods include

• Roof turbines - use aluminum blades to rotate and ultimately pull hot air out of your attic and out into the air. They are great at using wind energy from both electricity and the outside air since the blades can be naturally propelled using wind.
• Solar-powered attic fans - take away the energy concerns that other electric-powered attic fans face. They provide cooling benefits without adding to your energy bill and qualify for federal tax credits and other rebates. Many fans include a thermometer and only activate during the hottest part of the day to be more efficient. 

In conclusion, whether your home would benefit from a vented or unvented attic depends a lot on the home’s construction and materials, the interior and exterior temperatures and humidity, your HVAC and ductwork and other structural elements as well as your personal preferences. Koala Insulation of South Miami offers free home assessments to determine your insulation and ventilation needs and help you make the best decision for your home.