Heating & Cooling

How Do I Know If My Ridge Vent Is Working?

Ridge Venting Lg

When you have a new home, an old home, or simply an established home you bought from someone, it can be unclear how to test everything. Many parts of the house will need to be checked as you start moving in, with one of the most important ones being your ridge vent.

Ridge vents will only work if there is sufficient soffit venting. Ridge vents don’t work well by themselves. They need clear soffit vents to draw in cooler outside air heavier than the hot attic air. The cool denser air forces hot air out through the ridge vent, thus cooling the attic. An adequately vented attic should only be about 125 to 135 degrees Fahrenheit on most Summer days.

To test if your ridge vent is working inside your attic, use an infrared thermometer to take a temperature reading from your soffit venting and second reading from the ridge vent inside the attic. You should see a significant range in temperature variance where the soffit venting is lower, and the ridge venting is much hotter.

Understanding every way you can test your ridge vent and its importance will help your home stay livable. We have seen many people underestimate the importance of the ridge vent, ending up with poorly ventilated homes and slowly becoming moldy.

What Are the Tests That Can Be Done?

When it comes to testing whether the ridge vent works, you can and will find yourself using a few creative techniques. We always recommend that people follow the preferred method, but sometimes it can be tough to do when you do not have the right equipment or want to be safe.

The quickest ways of testing if a ridge vent works or not are also some of the simplest ways is with a smoke test. We have several tests, ranging from the dangerous but straightforward to the complex but safe ways of seeing whether or not your ridge vents are venting.

Preferred Method: The Air Temperature Test

Doing this test is by far one of the best ways to test the ridge vent; however, you will have to purchase something that can measure air temperature, such as an infrared thermometer. I use a Klien Tools Infrared Thermometer, which is available at Amazon. By measuring the temperature at the soffit vents, then measuring the temperature inside the attic at the ridge vent, you can see if it is working.

An active ridge vent will have the attic or roof be closer to the same temperatures as the rest of the house as the warmer air exits through the ridge. Suppose your ridge vent was not working or was slow to work. In that case, the attic temperature difference will be dramatic, with your roof or attic being almost double the temperature of everywhere else.

Other Free or Low-Cost Testing Methods

The Smoke Test

We always recommend using something that makes a lot of smoke but does not fire, like a smoke bomb or other novelty product. However, even with this, if the ridge vent does not work, you can find yourself in a room rapidly filling with smoke, which is why you need to light the smoke and leave.

Once the smoke has started filling your attic or the home’s rafters, it should start escaping out of your ridge vent. You should perform this test in the light of day when you can see the smoke rising from the ridge vent, as you will most likely not be able to see the smoke rising after dark.

The Fumes Test

A much safer but not as effective method of testing your ridge vent is by using something that can let off a smell, either incense or a candle, in the attic space. Light the product and let its smell slowly permeate throughout the area; you should be on the roof and eventually able to smell it.

Naturally, you cannot use something that will create a scent that will go down, which is why incense or a candle needs to be used. Further, it may not be as effective, but it will let you know whether or not air is moving from the ridge vent onto the roof, where it can safely dissipate over time.

The Light Test

If you are worried that the ridge vent is not working and the sun has already set, the quickest way to test it will be to use light. Turning on the attic light or placing a strong flashlight in the roof, where your rafter is, should shine a visible light from the side of the home.

If you look up from the side of the house into the area where the ridge vent is, you should see the light. It can indicate the ridge vent is working. However, some ridge vents have mesh to prevent animals from entering, which might obscure the light.

The light test also doesn’t take into account whether the soffit vents are working correctly.

Do Ridge Vents Get Clogged?

Ridge vents can easily become clogged as they are filled with dust, mold, mildew, or animals making nests near or in them. Most of the time, it will take several years for your ridge vents to become clogged, with most houses taking several years to get even some clogs.

We always recommend that you take a leaf blower up onto the roof once a year to clean and clear out anything that may be stuck in the ridge vent. We also recommend that you spray the entire surface in and around the ridge vent with a bleach or ammonia solution, killing any mold that may be growing.

Birds and squirrels are usually the animals that will make some nest in the ridge vent, as it is a dry location with hot air throughout the year. Fortunately, these animals abandon their nests throughout the year and give you the chance to safely and peacefully remove them to prevent complete clogging.

Should You See Light Through a Ridge Vent?

Yes, you should always see the light coming from the ridge vents when you look up at them from the side of the house. Light coming through the ridge vent can indicate that they are not clogged and that both air and light can freely travel through the ridge vent without becoming obstructed.

We always recommend that people consider this when they are first checking out a house or checking to see if a newly built home has been done correctly. Looking at a house in the dead of night will usually give the entire house a completely different look, allowing you to get a better feel.

It is also a quick way to see if the ridge vents of the home are in good working condition, allowing you to see every part of the vent without using smoke. However, we need to add that the light should only be visible from the bottom of the house, not when you are on the roof.

What Is the Purpose of A Ridge Vent?

Now that we know how to check whether or not the ridge vent is working, you may be wondering why the ridge vents need to be clear. We have talked to many people that have never heard of ridge vents and are still unsure about their overall purpose.

Ridge vents are not the normal thing to have on your home and can be confusing if you have a more traditional-style home. Ridge vents are added on the planning stages of the home, with the insulation and structure of the entire house built around the ridge vent being there.

Vent Air

The main reason your ridge vent will be installed and needs to be kept unclogged is that it will be venting all the excess hot air from your home. Further, the ridge vent will ensure that fresh air also enters the house throughout the seasons.

As the home heats up, hot air will naturally start to rise, with the ridge vent ensuring that the hot air does not get trapped inside of your roof or attic. As the hot air leaves your home fresh, colder air can enter through other openings to cool down the entire house in warmer seasons or to introduce oxygen in the winter.

Reduce Air Pressure

It may seem odd, but the air pressure in your home can cause a problem when it gets too low or gets too high, with the ridge vent ensuring that neither ever happens. As the ridge vents work, they will allow the air pressure in your home to always stay at the best possible levels.

We have seen several people surprised when their homes become uncomfortable when they have everything closed and sealed. However, too much positive or negative air in a home means no air flowing into it, which increases carbon dioxide levels over time.

Increase Air Flow

Naturally, as the air has somewhere to go at all times, the airflow in your home will be increased drastically once you have a ridge vent. This can be felt the most during summer, as the ridge vent quickly ventilates all the hot air that accumulates and allows for fresher air to enter.

However, in the winter, the effect is entirely different; as you want the hot air to stay in the house, the ridge vent helps to create a hot air pocket around the roof. This prevents a lot of the heat you need for the inside of the home from losing too much heat but still introducing fresh oxygen.

Lower Temperature

This is the primary function of the ridge vent and will only be effective during the summer months when you have all your doors and windows open. The ridge vent will constantly vent hot air and lower the temperature throughout your home as everything starts heating up in the summer.

We have seen many people that do not quite understand how this works and will actively diminish the ability of the ridge vent to work by leaving roof openings and attics open when it gets hot. However, the house and insulation are built to take the hot air to the attic passively and then vented.

Reduce Moisture

The quickest way for moisture to enter and accumulate in any location is fully enclosed, with nothing there to help the moisture evaporate. Ridge vents help to prevent this by having a natural drying effect on all moisture that will accumulate inside the attic or the roof.

Simply having the air move and the hot or cold air be vented will cause moisture levels throughout the house to decrease drastically. Doing this is vital to handling any mold or unwanted things from growing throughout your home as the years go by, as moisture will cause long-term damage.

How Does the Ridge Vent In An Attic Work?

Ridge vents are not simply openings at the top of your roof; they are connected to a system of internal ventilation that roots hot air from parts of the house and from outside to go out the top. This movement of air lowers the house temperature and prevents the top of the house from overheating.

Ridge vents work the best when you have a living space at the top of your house, as there will be less ventilation between the roof and the room located here—creating more potential for heat to get stuck in this area and cause a drastic overheating as time passes.

We always recommend that you have the ridge vent screened off as well, as critters and birds will try to make a nest in the space if they can gain access. However, the ridge vent will exhaust hot air from the house structure, cooling everything down and balancing pressure.

Is It Normal to See Light Through Ridge Vents?

You should see the light through the ridge vent, whether you are looking at it from home’s inside or looking at it from the outside. If you have spots where the light does not shine through, you will need to investigate and ensure that the vent is not clogged.

Usually, vents will become clogged as leaves, twigs, and other debris gathers up; however, animals will also make nests in ridge vents wherever they can. When this happens, you will have to go onto the roof or hire someone to go up and clean out the ridge vent.

We do not recommend using a pressure washer to clean out ridge vents as the water will leak through and cause massive problems and start to puddle on the inside. Further, if you have things stored in the attic or room under the ridge vent, everything will get soaked through.


Your ridge vent will be a low-maintenance part of your home for most of the year; however, we do recommend that you clean it at least once a year for safety. Many animals and unwanted debris will see the ridge vent as the perfect place to start their own homes, making the ridge vent work a lot less.

Please, always remember that it’s easier to clean the ridge vents in summer than it is to slip and slide on the roof during winter!


How Do Ridge Vents Work?


Hubert Miles | Licensed Home Inspector, CMI, CPI

Hubert Miles is a licensed home inspector (RBI# 2556) with more than two decades of experience in inspection and construction. Since 2008, he has been serving South Carolina through his company, Patriot Home Inspections LLC. As a Certified Master Inspector, Hubert is dedicated to providing his expertise in home inspections, repairs, maintenance, and DIY projects.