How to Determine Attic Ventilation for Energy Economy

Attic ventilation is always a concern when you are considering installing new upgrades to your home to make it more energy efficient. Like most home improvement products, ventilation products use different methods to move the air around in your attic; therefore, it is important that you read and understand the manufacturer’s material before deciding which is best for your home.

Tools and Materials Needed:

  • Ladder
  • Attic fan
  • Tape measure
  • Utility knife
  • Saw
  • Adhesive
  • Screwdriver

Step 1 - Calculating to Determine Proper Attic Ventilation

In order to install proper ventilation in your attic, measure the dimension of your attic, measure the length of your attic then the width of your attic and then multiply them together to calculate the square footage. Once you know the square footage, you will be able to calculate the ventilation requirements. Usually 1 square foot of ventilation is needed for each 300 square foot of attic space you have measured. In wetter climates you may require additional ventilation, but checking with the building code office in your area can easily answer this question.

Step 2 - Choosing the Correct Ventilation System

Today, there are many types of ventilation available for your attic and when choosing the type that suits your attic best will depend on the climate you live in, the shape of your roof, the roofing materials used on your roof and the building style of your home. When in doubt, talk to the people at your local hardware store. The kind sales representatives might have educational materials available to them which can help you make the correct choice.

Step 3 - Installing Attic Vents

After you have chosen whether to install roof line vents, gable vents, eave vents, soffit vents, exhaust vents, power vents or a type suitable to your project, you need to measure and lay out the location where each vent will be installed between the rafters. Once you have determined the location and marked the spot, all you have to do is cut the hole for your attic vent using a saw or utility knife, depending on the material. Once you have levelled your vent, simply use your screwdriver and screw the vent to the soffit area to cover the hole you cut.

Step 4 - Installing an Attic Fan

Once you have selected the location in your attic for installation, usually the southern exposure with the most sunshine is the best location. Generally, a placement near the center of the rafters is preferred as this will ensure clearance underneath. Using a saw, cut a hole the same size as the ceiling fan and place the fan in the hole from the underside of the roof. The flashing should be under the roofing materials with the lower portion of the flashing on the topside. Fasten the fan to the roof using the appropriate type of roofing adhesive. Replace any materials for the roof so that both sides of the flashing are covered and the roof is again weather tight.

Step 5 - Hints and Tips for Attic Ventilation

Attic fans should be installed close to the roof top to achieve best efficiency. When using a fan it is often recommended that you also use soffit and gable venting to make your ventilation more energy effective. Never install attic fans in the shade or under overhanging trees.