Outdoor temperatures and our energy bills have a high correlation. But we can minimize the correlation coefficient with proper building practices. In today’s Learn post, we are going to discuss attic venting and proper venting can help lower your energy bills.
Attic venting is a two part system. You need a place for hot air and humidity to escape and for cooler air to enter. Heat rises so there should be some form a venting at the ridge lines of the home. The ridge lines are the upper most parts of the roof system. The lowest portions of the roof should have soffit venting to allow for cooler, fresh air to enter the attic space. Soffits are the overhanging portion of the room which run parallel with the ground below. If you stand with your back against the exterior wall and look up, chances are your looking at the soffits.
How much venting do I need?
As a general rule, you should have 1 square foot of venting for every 150 square feet of attic space. We recommend you try to spread this our around the home to allow all portions of the attic to be properly vented.
Upper Most Venting
The upper most venting is where heat escapes. This venting comes in several forms. Here is a list of the types:
Gable Vents: These are vents on the siding of the home typically in the “pyramid” portion of the siding where the roof comes to a point. Not all houses have a gable roof so this isn’t applicable to all homes.
Ridge Vents: These are what I like to see, because they offer continuous venting throughout the entire ridge if installed properly. The proper install on these is to cut the roof decking at the upper most part. Then you install these plastic ridge vent covers which then are covered with ridge shingles.
Turbines: Sometimes these are called whirly birds. These are the most common venting systems in the areas we live in. They are effective and efficient and allow heat to escape. Many people think these spin because the wind is blowing them, while that can be the case, many times turbines are spinning because heat is rising from the attic causing them to spin and crease a “suction” to assist in pulling the heat out. So if your turbines do not spin well, we suggest you have them replaced because that is hindering their performance.
Lower Venting
The lower vent is often the vent missing on homes. Remember proper venting is a two part system and you should have both for maximum effectiveness.
Metal Soffit Vent: These are individual vents which you install by cutting the soffits. These are super easy to install for the avid DIYer.
Continuous Soffit Vent: This is by far the best product. We see this mainly on new construction because you would have to replace all your existing soffit to use this product. So if your about to build a new home, we highly recommend you use continuous soffit vent products. James Hardi makes a great product but there are other brands out there that work great too. There are also a few PVC or vinyl products you could pickup as well.
Final Thoughts
If you are planning to use spray foam on your roof deck, we recommend against any venting. Using spray foam makes the attic a part of the thermal envelope of your home becoming a conditioned space. You don’t want to risk any moisture or high humidity levels which could cause mold between the spray foam and the roof deck.
