Roof Turbine Vents – What They Are & How They Work

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Turbine ventilation system on rooftop

Plenty of people have seen the metal dome-like object at the top of the roof. What are they and what do they do? These objects also bear the name of roof turbine vents or whirlybirds because of how they throw hot air out of the attic. The spinning action of the roof turbine vents draws the air from the attic and the vents keep the attic cooler. Why might this matter? Over the summer months, temperatures in the attic have the potential to reach as high as 150 degrees.

What Are Roof Turbine Vents?

Roof turbine vents keep the attic cooler over the summer months, and they lower the stress placed on the air conditioner. Over the long term, you see a reduction on your electric bill because of how it uses less energy with these vents. The HVAC system doesn’t have to work hard to keep the home cooled, and as a result, the savings go straight into your wallet. Especially in the attic, you need proper ventilation because as moisture accumulates it rots the studs and decreases the lifetime of your roof. Poor ventilation in the attic also causes dangerous heat buildup.

Based on information from the National Roofing Contractors Association, a balanced ventilation system works best. You will want one square foot of total ventilation for every 150 square feet. If you have a vapor retarder present, then you don’t need as many roof turbines. Usually, for colder climates you will use a vapor retarder. You have to do a little math to figure this out. You want 50 percent intake with 50 percent exhaust.

How Do Roof Turbine Vents Work?

The basic concept behind the roof turbine vents is how the spinning blades at the top of the roof force out the hot air. Roofing contractors install these vents at the top of the roof because it forces hot air out of the attic. Heat rises naturally, so as the hot air reaches the ceiling, the roof turbine vents pull the less dense hot air out of the home and back outside. Commercial uses of these turbines will sometimes mean they get connected to gigantic fans on the underside. This will also draw other things out of the home like smoke. With domestic ventilation turbines, however, you don’t have the fan like you do with commercial. Some people have cited the issue of how a typical ridge vent stops the rising hot air because of an inverted V at the upper part of the vent.

How Well Do They Perform?

A few roofing contractors doubt the effectiveness of these vents compared to what you might get with one of the other ventilation techniques. For example, the American Society of Heating, Refrigerating, and Air Conditioning Engineers, Inc. conducted a study in 2002 that found how this reduced the cooling load by less than three percent in some of the test homes. Other strategies have sometimes proven more effective at venting the cooling load as part of the strategy for air flow.

However, more recent findings suggest otherwise. Air Vent, for example, did a case study with more than 30 homes in Mansfield, Texas, to analyze the temperatures and readings over a 12-hour period. After installing roof turbine vents on the home, the temperatures in the attic went from 123.2°F to 113.9°F. The results showed not just how the temperature was lowered, the temperatures on the roof deck materials were also lowered from 146.5°F to 124°F.

The Speed of the Turbines

The turbines on this fan run at as little as five miles per hour, but it can remove as much as 347 cubic feet of air from the attic at those speeds. When the speed of the turbines increases, the results look even more impressive. With this turbine type, you have to make sure you keep the soffits clear of attic insulation because you want to make sure that the same amount of air being expelled remains the same as the air being pulled in. Otherwise, the turbine will pull air from the interior of the home, and this becomes a waste of energy.

Pros of Roof Turbine Vents

  • Lowers the temperature of your attic
  • Reduces the cost of cooling your home
  • Gives you proper ventilation in the attic to keep your roof healthy
  • Less stress on your HVAC system so that it lasts longer
  • Interior temperature of the walls ceilings and attics are less
  • Remove large amounts of air through the attic

Cons of Roof Turbine Vents

  • Not all roof turbines will fit all pitches
  • Aluminum turbine best choice so that it doesn’t rust
  • Ensure ball bearings lubricated and sealed to stop a squeaky roof turbine

Installing Roof Vents

Before you can install roof turbine vents, the installers will first prepare the roof. For example, they should first understand where to place the vents. They have to drill a hole through the decking of the roof and do this for all the turbine vents. Next, the installer will climb onto the roof to cut the vent holes. The shingles around the section where the turbine vent gets installed will be removed and the installers remove the nails to install vent. In general, it takes less than 15 minutes to install, and it will cost around $50 per roof turbine vent, and this is a high-quality one.

Summing Up

Roof turbine vents work better than ridge turbine vents because the blades pull cool air in and the hot air out. When you see the turbines spinning, it means they’re sucking the hot air out of the home. Roof turbines will also usually cost less than a ridge turbine, and roof turbines provide you with better air flow. Regardless of what you choose, however, you should hire a licensed and insured roofing contractor to take on this job and make sure it gets done right.

Image from depositphotos.com.