The only right answer to this question is, all of them.
Roof ventilation aids many benefits and prevents a multitude of issues/problems for your home. First let’s go over what roof ventilation is;
Ventilation is the taking in of fresh air into the attic space of your home and exhausting out the hot air. It’s just that simple. The best time to address ventilation concerns is during a roof replacement Atlanta.
In order to make this happen you have to have 2 things;
Soffit Vents and either a gravity style vent or a power vent.
Like the name implies, are installed into the soffit of your home. You can have individual vents that are spaced apart and installed around the perimeter of the home or you can have continuous soffit vents, either one is fine, and are absolutely necessary for the ventilation process to work.
This is going to be the part of the ventilation system that will intake the fresh air into the home.
Now you are going to need to decide on what other type of vent you want to use to exhaust the hot air. This is where most of your options are going to be. Please note that all ventilation will be a benefit to the home and there is no wrong answer, however, depending on the style of your roof, some choices may be better than others. This is where the advice of a roofing contractor will come in handy.
We are going to go over a few of the more widely chosen options for static or gravity ventilation.
What they mean by that term is simply that this style of ventilation does not use power or electricity, it works naturally by gravity.
This is by far the most common choice for most homeowners.
It is installed along the top peaks of the roof and is then covered with shingles to make it blend into the overall appearance of the roof. Air is pulled in through the soffit vents and the hot air trapped in the attic space is then forced out through the ridge vent at the top of the roof. This is an extremely thorough way to vent your roof that does not cost money to use. For these reasons and due to the fact that it will exhaust the most amount of air compared to some of the other ventilation options available, it is the most popular choice
Box Vents and 750 Vents-
Work much the same way that ridge vents do, the principal is the same however they look very different. Box vents are also installed near the top of the roof line, however these are installed by cutting small holes into the plywood decking, just below the peak of the roof and attaching them over the holes. These also use the soffit vents to pull the air in and exhaust it out through the box vents. These are ideal if you have an attic space that is not huge or more than one smaller attic space that you need to ventilate.
750 vents are also sometimes referred to as Slant Back Vents and these are just like a box vent, only they are slightly larger than the box vent. These could be used to vent a slightly larger attic space.
Turbines or Whirly Bird Vents-
I am sure you have all seen one of these styles of vents at some point. They are an older style metal vent that protrudes above the roof line and is circular in shape. The most notable feature is the round blades that you can see spinning around as the wind blows. While these vents are perfectly acceptable and they do work to move a good amount of hot air out of the attic, they just don’t have the same appeal that they once did. This is probably due to the bulky look.
Now let’s move on to the powered ventilation options;
These are a great option especially if you have a large space that you need to move hot air out of. These vents also rely on the use of the soffit vents, however, these use electricity to pull the hot air out of your attic. This option helps to keep your attic at a constant temperature, but does cost money to run it. Also something to consider is that since this is a motorized vent fan, it will also be something that will need to be replaced after so many years.
Solar Powered Attic Fan–
This vent offers the same benefits of a power fan with almost none of the cost.
This much like the power fan will have to be replaced periodically due to the motor eventually wearing out.
Now that we have a basic understanding of what ventilation is and how it works, we should also go over some of the drawbacks of not having it and the consequences. First and foremost, your roof can’t breath and this can be a bad thing for so many reasons.
When the hot air cannot escape out of the attic where it is trapped, it will actually start to condensate. Water droplets will form and can drip onto the attic floor or onto the drywall below it and will show up as water stains. You will see water staining on the ceiling below that area and think that you have a roof leak.
Expansion/Contraction of your wood decking–
Your shingles are attached to your roof by way of nails driven into the wood decking. When there is not proper ventilation in the attic, the plywood expands with the heat of the sun and contracts as the temperature drops in the evenings, which in turn pushes the nails that are securing your shingles up and out of the decking. This can and does cause the nails to eventually work their way out and your shingles to come loose. Your roof is now vulnerable to water intrusion.
Shingle Failure/Granular Loss-
When hot air sits in the attic and has no way to escape, the temperatures soar. It is not unusual for the temperatures in your home to rise and stay in the 130-140 degree temperature range in the summertime. Shingles are made from asphalt and when heated to those temperatures from the inside and outside, it will cause the shingles to become very pliable and lose more granules than normal.
Heating and Cooling–
Due to the higher temperatures inside the attic, it will also raise the temperatures inside the living areas of your home as well. This will cause your air conditioning unit to have to work over time to try to cool your home, which will also put more strain on your condenser and cause it to need to be replaced sooner.
It is now the building code in most states that adequate ventilation be installed. If you currently have a home that does not have ventilation, when you do replace your roof, it will be necessary to install it.
Please note that if you are considering having Spray Foam insulation installed inside the attic of your home and you have a new or newer roof that is still under warranty, this will void your labor and workmanship and manufacturers warranty on your roof. In order for spray foam to be installed, they have to remove and close off all vents, thus not allowing your roof to breathe and will shorten the life expectancy of your shingles and roofing components.