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In order to know how many roof vents you should have, you need to know what roof vents are and why they’re important

Roof vents essentially help your house breathe. Think of it like a pressure cooker:

Heat builds inside of the cooker until that energy needs to be released. Once you open the valve, the heat escapes as steam. In turn, this helps to manage the temperature in the cooker.

Roof ventilation operates the same way.

Heat builds within the house and needs a pathway to escape. Roof vents act like the valve inside of a cooker and allows the heat to leave the house, which keeps your home comforta

In this article, we’ll discuss the fundamentals of roof vents and how many you’ll need to get the best ventilation for your home.

How Do Roof Vents Work Exactly?

Roof vents are part of a larger roof ventilation system.

Simply, there are intakes, called soffits, located on the underside of your roof that draw air from the outside environment into your attic.

The roof vents act as exhausts that  provide outflow for trapped air.

This soffit-roof vent relationship is a complete roof ventilation system and is critical for all houses.

Why Do You Need Roof Vents?

There are two seasons and one area of the house to think about when discussing roof vents.

Summer, winter, and your attic.

The heat trapped in your attic in both seasons can severely affect your wallet.


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During the summer heat gets trapped inside of your attic; it can often be hotter in there than outside. This heat travels downwards into the rest of your home causing more strain on your air-conditioning units and thus driving your electric bill up.

Not only can your electric bill go up, but the extreme temperature build up can lead to advanced warping and blistering of the roof’s shingles. This lowers the product life of your roof and leads to higher maintenance costs over time.

Having ceiling vents in your attic allows the excess heat to escape and lower temperatures in your house overall as well as extend the life of your shingles


You might think trapped heat in your attic–and therefore the rest of your home–would be a benefit to your heating bill. You would be wrong.

In the winter, heat trapped in your attic melts the snow on your roof–not fully though. That water refreezes in rain gutters blocking them and adds to the moisture sitting on your roof.

The added moisture combined with the heat of your attic can lead to mold, mildew, rot, and accelerated wear and tear of your roof.

All of this adds to not only roof maintenance costs, but air cleaning within the home if mold becomes a major problem.

Having ceiling vents allows the temperature to balance between your home and the outside environment and will lead to lower maintenance costs overall.


There are 4 major roof vent types:

Standard Box

This is the most basic, no frills version of a roof vent. A simple square design planted over a small hole in your roof.

Standard Box vents operate by wind-based or cross-ventilation. This means that the natural air flow in your environment is responsible for the exhausting of the air in your attic.

If installed properly these will last for up to 20 years; If installed incorrectly, they are prone to leaks.

Standard box vents will rust overtime but do provide good quality for the cost.


These vents are a step up from Standard Box vents. Again, a simple square base that fits over a small hole cut into your roof.

WhirlyBirds add mechanical fan blades to the insides of the vent casing. This provides two methods for air exhaust; both powered by cross-ventilation but because of the fan blades the air flow in the environment works with the spinning of the blades to create greater suction of your attic’s air outwards.

Since WhirlyBirds physically spin, they can be noisy and just like Standard Box vents, if installed incorrectly can lead to leaks.


This solution provides added suction to outward airflow from your home’s attic.

Unlike the manual blades in a WhirlyBird, however, this vent is powered by your home’s electricity.

The same principle of intake-outflow applies just aided by an automatic process.

There is ongoing debate on whether or not Power Vents are worth the added cost and moving parts. Some say the vent is not providing proper outflow from your attic in order to cool it, but simply drawing in air from the rest of your home’s air conditioned rooms. In any case, Power Vents can be considered the worst out of all these ventilation options.


Perhaps the best of all options, Ridge vents have the fewest moving parts, are the most physically stable, and cover the most surface area.

Ridge solutions come in either metal or plastic and work by fitting over the apex point of your roof–where the two sides of your roof meet to form the tip of a triangle. This solution is essentially a Standard Box stretched over a longer, narrower area of your roof.

Since the Ridge fits securely over your roof’s apex, especially plastic models, there is rarely any damage caused by leaks.

Unfortunately, because of the nature of this solution, oddly shaped roofs cannot take advantage of the ridge design.

Finally, How Do I Properly Vent A Roof?

For roof ventilation installation, the general rule of thumb for square-based venting solutions–Standard, WhirlyBird, Power–is one vent for every 300 square feet of your attic space.

How you install a square-based roof vent changes slightly depending on the state of your roof.

Be sure to consult or hire a professional before performing your own roof ventilation installation.

There are many factors you need to consider:

  • Tools for the job
  • Hole diameter
  • Hole spacing and placement
  • Navigating your roof’s shingle layout
  • Securing the seams to prevent leakage

For roofs where shingles are already laid, in general, you’ll want to:

  1. Using your roof vent as a guide, measure the width and length (plus half-an-inch for each) needed to cut into your shingles to create a square opening. It’s important to use the vent itself as the measure, not the base of the roof vent
  2. Cut out a square from your shingles using the measurements from Step 1 as a guide. The cut shingles can be discarded.
  3. Remove any nails within the exposed area of the roof and any nails that lie along the border of your new square. These nails will get in the way of the base of the roof vent once you start inserting it. Be careful not to damage the shingles during this process.
  4. In the center of the exposed square of your roof, cut an 8×8 inch or 10 x 10 inch circle, depending on the diameter of your roof vent, into your roof exposing your attic.
  5. Install the roof vent by sliding the base of the vent underneath the shingles on the border of the square created in Step 2. Be sure to nail down the base of your new roof vent to prevent leakage. Also be sure to nail down the shingles to the side of your roof vent to prevent leakage.

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