What Are the Signs That My Attic Does Not Have Proper Ventilation?

Are you concerned that your roof might be deteriorating without your knowledge due to poor ventilation? Are you worried that you’re already facing costly repairs and want to avoid further damage?

At RoofSmart, we do not just focus on your roof. During our thorough inspection process, one of our meticulous roofing nerds examines the areas in and around each customer’s roof. This includes attics, ceilings, siding, and gutters. As a result, we can catch issues in these areas that would otherwise cause expensive damage to your roof later on.

We are one of the few roofing companies in the Greater Seattle area that will look at your attic ventilation and determine if it is up to code.

In this article, you’ll learn:

• How to identify signs of poor attic ventilation
• Why having poor attic ventilation is bad for your home
• What to do when you notice signs of poor attic ventilation

By the end, you’ll know what to look for so that you can call in an expert to help you fix your attic ventilation before things get any worse.

What causes a roof to have improper ventilation?

The quick answer to this question is that there is some sort of design failure, which can happen in many different ways.

Building codes are constantly changing, so it’s likely that your home might not be completely up to date. If your home is several decades old, then your attic ventilation might have been installed before a major update to building codes was made.

Other times you might have a home that wasn’t designed with attic ventilation in mind. Or, during the process of building your home plans might have been changed without considering attic ventilation. With so many people making decisions on a big project like building a house, it can be easy for details to get overlooked.

How do I know my attic doesn’t have proper ventilation?

If you suspect that your attic does not have good ventilation, there are some ways to investigate this on your own.

Excessive heat in the attic

A properly designed and ventilated attic will generally be within 15 degrees of the outside air.

So, if it’s a summer day and you take the temperature at the overhang, and then you pop the top of the attic hatch and check the temperature up at the ridge, it should be 15 to 20 degrees hotter.

If it’s more than that, that’s not good. It means that your attic is getting excessively hot way too easily and the air is not flowing enough.

Mold infestation

Another way you can tell is if you have mold. Seeing mold in your attic means that you probably don’t have good airflow because if you have a breeze in there, then it’ll carry out the moisture before it has a chance to turn into condensation and seep into the wood.

Ghosting

Ghosting is also an indicator of poor attic ventilation. Ghosting is mold showing through the ceiling of your living space. So, wherever you’ve got a truss or a ceiling joist, you’ll see a little bit of a black shadow running along the length of it which happens because of the mold bleeding through. When you notice ghosting then you know that your mold problem is really bad.

So in this cold, wet weather if you’ve got mold or in excessively hot weather those are the easy ways that you can tell as a homeowner.

What are the consequences of not fixing issues in my roof caused by improper ventilation?

Not having proper attic ventilation is bad in the hot weather because your roof will be way hotter than it should be. This is very bad for the shingles because if they are constantly exposed to that much heat from inside the roof, then they will start to degrade very quickly.

This means that you will likely only get half the life out of your roof because letting a roof roast in the heat can take decades off of its life. The shingles will start to curl up or crack, which means that they need to be replaced.

If you have a mold infestation and you do not address it, sometimes it can negatively impact your health. This is especially true if the mold issue is extensive enough to seep through the attic and cause ghosting.

Also, the mold will continue to spread and worsen, making it increasingly more expensive and difficult to deal with the longer you wait.

What should I do when I notice signs of improper ventilation?

In order to make sure that your attic ventilation is up to code and functioning properly, you’ll need to do some math.

Building code requires that for every 150 square feet of attic floor space, you must have one square foot of ventilation. But all the ventilation products available for you to purchase are denominated in square inches, so while you’re calculating everything you have to convert it to inches.

Follow these steps:

1.) Calculate the total square feet of your attic by multiplying the length by the width.

2.) Convert that number to square inches. You can convert the total square feet of your attic to square inches by multiplying it by 144 (because that is 12 X 12 square inches per square foot).

3.) Divide the number you get by 150 to know how much ventilation you need.

So, for example, let’s say your attic floor space is 50 ft long and 20 ft wide. Multiply those numbers and get 1,000 square feet. Then, you would multiply 1,000 square feet by 144 and divide the total by 150. The number you get is how many square inches of ventilation you need. In this example, it is 960 square inches.

To make this even more complicated, the amount of required ventilation must be split between intake and exhaust. Most people have bird blockers around the edges of their roofs as intake and ridge vents on the top as exhaust.

If you don’t want to do that math yourself, then you can hire a building science engineer or consultant to help you out. After that, you can hire a roofing contractor to make the changes to your ventilation system based on what the building science engineer calculated.

Don’t Let Poor Ventilation Go Unchecked: Your Next Steps

Spotting signs of poor attic ventilation is crucial, but addressing the issue promptly is even more important. Poor attic ventilation might seem like a minor issue, but its consequences can be severe—from deteriorating shingles to dangerous mold infestations.

Understanding the signs, such as excessive heat, mold, and ghosting, is the first step to protecting your home and extending the lifespan of your roof. Ignoring these problems can lead to costly repairs and even health hazards from mold exposure.

Want to learn more about what proper attic ventilation is and why roofers don’t usually address it? Read our article “Attic Ventilation Is Vital But Most Roofers Get It Wrong” for more information on ventilation issues.