Southside Exteriors

Roofing | Siding | Doors | Windows

Home Exterior Contractor serving the Hampton Roads area of Virginia

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Roofing | Siding | Doors | Windows

Home Exterior Contractor serving the Hampton Roads area of Virginia

Request a Free Quote

5 Mistakes That Are Common When Ventilating An Attic

In many cases, all or part of your HVAC equipment is in your attic.  Your attic gets extremely hot in the summertime which heats up your HVAC system, air ducts, and your ceiling (all of which makes the system have to work harder to cool your home).  Based on that information, it is very important to ensure that your attic is properly vented.  A Professional Roof Contractor, such as Southside Exteriors, can properly ventilate your attic to help make your home more energy efficient.

In this article, we’re going to cover 5 common mistakes that are made when ventilating an attic.

1. Installing the exhaust vents too low and/or the intake vents too high

Your attic ventilation system needs a steady supply of cool air to be drawn in at the lowest possible point in your attic.  The exhaust from your ventilation system needs to be at the highest possible point.  In many cases, these vents are either reversed, placed at the same level, or placed too close together.  If any of these mistakes are made, your system will be inefficient or perhaps short-circuit itself which means it will not adequately ventilate your attic space.  The placements of the intake and exhaust is critical for your system to function at it’s maximum potential.  An intake that is too high or an exhaust that is too low will not deliver the desired performance.  The ideal intake location is at or near the level of the soffits.  The ideal exhaust location is at or near the ridge of the roof which is typically the highest point on your roof.

2. Installing More Than One Exhaust Fan

The best approach is to have one exhaust fan and one intake location that are installed per the previous section.  If more than one is installed, there is a possibility that one exhaust fan will overcome the other which will basically turn the less powerful exhaust fan into an intake.  This will cause a short-circuit and decrease the air flow that would otherwise be coming into the intake vent.

The ventilation system needs to meet the NVFA (Net Free Ventilating Area) of the attic space in your home.  For example, if a ridge vent is installed along with another type of ventilation system, such as an exhaust fan, the result can be a short-circuited ventilation system that doesn’t add to the efficiency of your home.  In fact, it will just be another electrical load (the fan running) that will decrease the overall efficiency of your home.  You need one balanced system that is properly sized for your particular application.

3. Your Ridge Vent Is Too Long

For aesthetics, many people want their ridge vent to cover the entire length of their roof, but the actual length of the vent that is cut into the roof doesn’t necessarily need to be the same length as the vent itself.  If the opening is too large, the roof ventilation system could suffer from having too much exhaust which will cause an imbalance in the system.  The size of the roof vent slot needs to accurately match the NFVA requirements for your attic space.  The calculator below will calculate the square footage of your ridge vent or soffit vent based on the CFM (Cubic Feet per Minute) of your attic exhaust system (fan).

Ridge Vent Calculator - Soffit Vent Calculator


Enter the CFM of your attic exhaust fan and the calculator will tell you the necessary square footage of your ridge vent or soffit vent.

4. Intake Vents that are Clogged or Completely Blocked

As a part of your annual home maintenance, you should ensure that your attic ventilation intake vents are clean.  Leaves, pine-straw, spider webs, and other related items will eventually clog up this vital part of your attic’s ventilation system.  If you have recently installed a system, you should verify that the holes were properly cut and that there isn’t any insulation from your attic blocking the air flow (stranger things have happened!).

Cleaning the air vents could be a dangerous job based on their potential location.  If you vents are located up high on you home, it is highly recommended that you hire a professional contractor to inspect and clean your vents on an annual basis.

5. No Intake or an Intake that is too small

There are countless homes that have DIY attic fans installed that don’t have any intake ports.  In other cases, there are intake ports, but they are too small to allow the correct amount of air flow (see the calculator above for the correct square footage of the intake port / ridge vent / soffit vent).  If no vent is present or it is too small, there will be an unnecessary additional load placed on the ventilation fan motor.  This will prematurely wear out the fan and it will cause it to pull extra amperage which translates to less overall home efficiency.  If there isn’t a vent or the vent is too small, the system will not be able to properly ventilate the attic space.

Attic ventilation is not a complex topic, but it is very important to ensure that it is done correctly to maximize the cooling benefits.

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