How much ventilation is needed in an attic?

shingle roof with attic ventilation exposed

Keeping your attic cool

Before we answer that question, why attic ventilation is important? The big one for you to know is attic ventilation saves you money, starting with your energy bills. Attic ventilation and insulation are important when it comes to those monthly cooling and heating bills. Attic ventilation also will keep your roof healthy and strong by allowing the heat and any moisture escape during the winter so that the attic stays dry, which reduces ice dams. Ice dams are a whole other subject!

 During the summer, the right amount of attic insulation installed correctly in the attic will reduce the heat transfer from the roof to your living area by as much as 25%. Any type of attic insulation, cellulose, fiberglass, or foam creates a barrier between where you and your family are and the UV rays that are beating down all summer. Attic ventilation during the summer pulls out what heat makes its way into the attic.

Why does attic need ventilation?

There are 2 types of vents that are primarily used for attic ventilation. As we learned in school, heat rises naturally, right? We can take advantage of that natural process to vent our attic and exchange cool air for warm air at the right time with attic ventilation placed: 

  • The intake vents – these should be placed under the eaves, in the lowest part of the roof. This will allow the cool air to enter the attic. Intake vents are typically installed precisely in the soffit, spaced every few feet. This pulls in the cool air unless…. You add insulation to the attic and block the vents.  
  • The hot air exhaust vents – there are three different ones needed for proper attic ventilation. The ridge vents are the openings that run the length of the roof along the ridge. If you don’t know roofing and attic ventilation, you wouldn’t know ridge vents are there because they are camouflaged by ridge shingles.

Then there are the static vents that typically are protruding from roofline through special covers that keep hail, rain, sleet, and snow out of the attic. And last, but just as important are the powered exhaust vents, either electric- or solar, that act as a wind turbine. When the temperature reaches a pre-determined limit inside the attic, it turns on and when the temperature drops back, the static vent turns off.

What happens if attic is not vented?

It will build up moisture. Attic ventilation keeps the outside air that comes in to flow back out and not sit in your attic. This airflow keeps excessive heat and moisture out, so it isn’t rotting the wood in your attic or the roof decking above the attic. You want attic ventilation to prevent mold, which is what you will have if that moisture gets in the attic and sit. With the air flowing through like this, it keeps the roof temperature from letting water freeze on top and create ice dams. 

How do you tell if your attic is properly ventilated?

During the summer, if your attic ventilation is good, it will reduce heat building up in the attic, which helps that monthly energy bill. During the winter, if your attic ventilation is good, the moist, warm air will escape out, and the attic stays dry and there are no ice dams on the roof. Four indicators that you need more attic ventilation are:

  1. If you look around your house and you don’t see any vents along the eaves or roof line, then you probably don’t have attic ventilation. Some house has a continuous, low profile ridge vent that runs along the roof peak, or there are gable vents, louvered openings found at gable tops. A professional roof inspection by roofing contractors and attic ventilation experts can determine this for you.
  2. On a warm and sunny day, touch your ceiling. If it is a hot ceiling, your attic is a solar oven, and that is not only costing you money on the energy bills, it is also cooking the roof shingles, shortening their lifespan.
  3. During the winter, if there are thick ice ridges on the eaves, you have poor to no attic ventilation, which is allowing the warm air that cost you money, is escaping from the living areas of your house and into the attic. This is melting the snow and then that water refreezes and creates ice dams.
  4. That escaped warm air is also carrying moisture to the attic which will condense on rafters or decking. If you notice any dampness or frost, your attic ventilation is lacking.

How do I get air circulation in my attic?

Add adequate attic ventilation by following these steps:  

  • In the attic, mark where the roof venting needs to be located – avoid placing them over the rafters.
  • Position them on the same side of the roof, running along the side that isn’t visible from a prominent side.
  • Now marked the locations with nails hammered in place through the shingles.
  • Have an even number of soffit vents evenly spaced on each side of the house.
  • From on top of the roof, look for nails and seams that will be your framing locations.
  • Mark the cutting lines with a cardboard template
  • Install the vents as instructed on the box or packaging. You can also find several videos online. Or call a professional roof who could have them installed by the time you finish the video.
attic ventilation on a tile roof

What is the best type of attic ventilation?

There is the wind turbine type of attic ventilation which works with the wind to pull hot and humid air out with a series of spinning vanes. Then there is the ridge vent that runs along the roof peak. There are no moving parts of this type of attic ventilation.

The ridge vent attic ventilation is less expensive, but if there is no wind, they aren’t working. The ridge vent style of attic ventilation can be expensive to install if there isn’t one because the entire roof peak must be removed. Between the two options, the turbine removes more air, but the ridge vent provides optimal performance by pulling air up and out the roof.

It doesn’t matter which type of attic ventilation you choose to go with, you just need to make sure you have it and it isn’t blocked.  The money you’ll save in energy bills will more than pay for the cost of having attic ventilation installed. Call Crosby Roofing at 478-785-2285 today for attic ventilation in Macon & Augusta, GA.