Skip to Main Content
Crew member working in crawl space

The Stack Effect

While you may not have previously heard of it, the ‘stack effect’ is a real problem for many Ohio homes, and it could be causing serious damage right under your nose.

Get a Free Estimate


If you have taken the time to do some research into the way crawl spaces are set up (and the most common issues that they can be afflicted with), there is a high chance that you have heard of the stack effect. This is a great advantage; there are many people who are not even aware of what the stack effect is. Of course, knowing about it and understanding it are two different matters entirely.

Understanding how the stack effect impacts your home will help you to understand the damage it can cause, both in your crawl space and in your wider home. This will help you to identify problem signs more effectively and, hopefully, allow you to catch damage before it snowballs out of control. Of course, if you ever feel that there may be damage at work in your home, we urge you to contact a professional as soon as possible

Stack Effect

What Is the Stack Effect?

The stack effect, sometimes referred to as the chimney effect, is a process that drives air throughout a building at an increased rate as a result of entry/exit ventilation points at the highest and lowest levels of a property. This movement is not the result of wind or wild weather, however, but by thermal differences and changes.

As air is heated, it becomes less dense and rises. A whole room/home will eventually become warmer as a result. When a property is correctly sealed, this has very little effect. However, when the stack effect is at work in a home, the rising of this warm air draws cold air in from outside the property, creating a constant state of movement.

When you start cooling your home, this process is reversed. The artificially cooled air will drop to the bottom of the house and draw in warm air from outside. As a result, the stack effect creates a constant state of change in your home that can cause a lot of problems and even damage.

What Can Cause the Stack Effect?

Most of the time, the stack effect will begin to work on a home when there is damage to the structure of a property or its windows/doors. You see, there are always ventilation points in the roof of a house, but the bottom of your home should be sealed against outside influences.

The most likely causes of the stack effect in a home are:

Open Crawl Space Vents

Crawl space vents were originally installed because they were believed to prevent damage and dampness by increasing airflow around a crawl space and home. They do increase airflow, of course, but they have now been recognized as damaging to the health of a crawl space.

Open crawl space vents are one of the most benign and easy to fix causes of the stack effect in any home, however, which is comforting. All you need to do to bring balance back to your property’s airflow is invest in basic crawl space encapsulation, in this case.

Damaged Windows or Window Frames

Damage to windows or window frames around a home can cause the stack effect to start impacting the interior climate. The most obvious cause would, of course, be a broken window, while smaller issues like windows that do not form a tight seal when they close and wooden window frames that have started to rot can also have an impact.

The impact of this damage is likely to start small, at first, and you may notice it because of movement in the curtains or shades over impacted windows, or a window’s tendency to rattle itself.

Loose or Ill-Fitting Doors

Doors that lead to the exterior of your property are incredibly important to the interior climate of your home. If they are loose, ill-fitting, or damaged in any way, they will let water and pests into your home, as well as disrupt the airflow.

Even a relatively small space can let in enough air to allow the stack effect to start working on your home. Of course, this will leave you with more worrying concerns than increased airflow.

Structural Damage

Structural damage to your property’s walls is also capable of causing the stack effect to go to work on your home, but it generally has to be advanced. After all, there must be a crack or hole big enough to allow excess airflow.

As such, the most common kinds of structural damage that can contribute to the stack effect are chunks of wall missing around utility intakes, windows, and doors.

In short, all that is really required to allow the stack effect to start working on your home is a gap or hole somewhere that it should not be found. Once the stack effect starts to go to work, however, a surprising amount of damage can start to show up.

The Damage That the Stack Effect Can Cause in a Property

Increased airflow around your home may not seem like a huge issue or even something to worry about at all, but the stack effect can contribute directly to problems that affect your property structure, your wallet, and even your health.

These are just some of the issues the stack effect can cause when it goes to work in your home:

Exacerbation of Allergies

As air is drawn into your home from outside, it will bring with it all of the detritus, dust, and pollen that is found in abundance out of doors. For people who have hay fever and pollen allergies, this can make spring and summertime incredibly unpleasant. Whereas an air-conditioned property should otherwise be allergy-friendly, a home that has the stack effect at work will provide no such respite.

For many people, this will be a mild irritation, but for those who have severe allergies, it can be a little more serious.

Airborne Contaminants That Cause Health Issues

The stack effect can also bring contaminants into a property that will have an impact upon your general health and well-being, even if you are otherwise healthy. The most obvious example of this is mold spores. Mold spores can be carried for miles on the air and are capable of taking root almost anywhere. All they need is a little humidity.

Once mold and mildew have made their home on your property, you will notice a number of side effects. As well as producing a musty smell, mold and mildew can irritate your skin, nose, throat, and eyes, and will exacerbate pre-existing respiratory conditions. For people who suffer from emphysema or bronchitis, for example, mold can be very dangerous. Even healthy people can develop serious migraines if they have black mold in their homes.

Condensation and Dampness

Increased airflow will bring humid air into your home from outside and cause condensation as a result of the clash between cold and warm air in various parts of your home. This increase in relative humidity will allow mold and mildew to spread and take root in areas that they normally would not be able to thrive in.

There is also a chance that you will see some damage to your property as a result of this dampness. High levels of humidity can cause wallpaper to bubble and peel and cause exposed wood to start rotting. This will have structural implications for your home, as well as cause issues for your health.

Increased Energy Use and Bills

Because of the way thermal changes and air movement contribute to the stack effect in a home, a property that is dealing with this issue will have a far less stable interior climate. This means fluctuations in temperature will become more common as artificially heated or cooled air leaves the home, drawing in air from the outside.

This is not only uncomfortable but will make your HVAC system work harder in order to give the same level of heating or cooling. As such, your energy consumption could increase hugely and, as a result, increase your energy costs.

As you can see, the stack effect is far from harmless. Any home dealing with this increase in airflow will face a number of issues including, but not limited to, health concerns, structural damage, and increased overhead costs for the running of the household.

Stack Effect

FAQs

The stack effect can occur in any home, but that does not mean it will affect every home. There are certain conditions required to produce the stack effect. In short, you need some kind of opening in the lower reaches of your home (since every home will have ventilation in place at the highest point of the property).

Exposed Crawl Spaces

One of the most common causes of the stack effect in homes around Cincinnati and Columbus, Ohio, is the presence of an exposed or non-encapsulated crawl space. The presence of open vents in particular can cause a lot of problems that go beyond the stack effect and may cause serious structural damage to both your crawl space and your wider home.

Thankfully, this issue is relatively easy to rectify, especially if your crawl space is otherwise in good health. If your crawl space has underlying damage that has been caused by persistent dampness and exposure, like wood rot and mold, you will have to deal with these issues before you seal the crawl space off. Once you encapsulate the area, however, the stack effect will cease to be an issue.

Structural Damage

If you have a basement, or your crawl space has already been waterproofed and encapsulated, there is a high chance that the cause of the stack effect in your home is some kind of structural damage. Generally speaking, there needs to be a sizable hole of some kind to cause a noticeable change (anything big enough to push your finger through will have an impact). Of course, if there is a number of smaller openings, this will have the same effect.

The kinds of structural damage most likely to cause the stack effect are damaged windows or doors, damaged window or door frames, unsealed utility entry or exit points (or points at which the seal has worn away), and serious structural damage to a property’s walls. If you are certain that something is going on in your home, but you cannot find the precise cause, it is time to call in a professional.

If you are certain that the stack effect is at work in your property, there are a few things you can do to protect your home’s internal environment.

Prevention

The best thing you can do to protect your home from the stack effect and the damage it can cause, of course, is to prevent it from taking root in the first place. In this endeavor, the best thing that you can do as a homeowner is encapsulate and waterproof your crawl space. By doing this, you will cut off the main source of exterior ventilation in the lower reaches of your home and protect your property from dampness and avoidable damage.

Secondly, you should check your windows, doors, and utility inlets/outlets for signs of damage and wear and tear. The degradation of the sealant around these areas is a common cause of the stack effect in many homes, as well as an entry point for moisture. As such, regularly inspecting them will allow you to renew the sealant and repair damage quickly, preventing further issues in your home.

Repair

Once there is damage in your home and the stack effect has started to take effect, there is nothing you can really do except repair the damage and seal off exterior ventilation points. This task can vary in size, depending on the nature of the damage and how long the issues have been at work before you noticed them and began to rectify them.

Of course, the more serious the damage is, the longer and more costly the repair process will be. If the cause of the stack effect is a seriously bowing wall, for example, the repairs could take some amount of excavation and time. By contrast, when the stack effect is being caused by an unsealed HVAC inlet or outlet somewhere in your home, it will simply be a case of renewing the sealant (assuming no secondary damage has occurred already).

There are certainly some things that you can undertake alone, but we always tell our clients that DIY work should end where structural repairs begin. If you want to renew any sealant yourself, there’s no reason why you shouldn’t, but once you start seeing indicators of structural damage, wood rot, or mold formation, it’s time to call in a professional

DIY Work Doesn’t Guarantee Results

While we understand that there are many skilled and knowledgeable DIY enthusiasts in the world today, no DIY work comes with a guarantee of efficiency. If you incorrectly diagnose the root cause of an issue, miss a contributing factor, or fail to notice secondary damage forming, the repairs that you perform may not be effective. If this happens the issue will inevitably recur at a later date, perhaps more strongly than before.

Far more worrying, however, is the thought that any ineffective or unsuitable repair could cause additional damage to your property. A good example of this would be performing crawl space encapsulation without dealing with saturated and rotting wood. This will only allow damage to percolate in your home and actually increase humidity, leading to a more serious form of rot and, as a result, tertiary problems that might never have formed otherwise.

Professional Services Come With Support at Every Step

Hiring a professional is by far the most cost-effective way to get a good result for your property. If you choose a crawl space and foundation specialist, you can be certain they will be able to deal with any issues that your home throws at them. You can also be sure that they will use the best possible products and equipment to undertake the work, meaning that you get a high-quality and durable result.

It is especially important that you hire a specialist if you suspect or have been told that there is a foundation or foundation wall problem at work in your home. Professionals will be able to talk you through the process, undertake the work safely, and provide appropriate support after the work has been completed to ensure that the repairs are staying strong. This kind of follow-up is important with foundation problems and structural damage because so much of the issue is about the soil around and under a home. 

Recognizing the Stack Effect

The stack effect can be incredibly subtle, especially if the damage allowing air in from the outside is quite small. Nonetheless, there are some signs of the stack effect that you can be on the lookout for.

It is important to remember that many of these can be signs of other forms of damage too. As such, you should call a professional to investigate when you see indicators of damage.

Slamming Doors and Windows

If you start to notice drafts around your home when there used to be none, or there are doors and window shutters slamming when they never used to, it is likely that the stack effect is at work. If you are not quite sure if there is a draft in your home, you can try hanging up a ribbon, a bit of string, or a sheet of paper. If it moves without being touched, and no windows are open, there is a draft in the room.

Increased Energy Bills

If your energy bills start to increase without reason, even if the increases are small, it could possibly be a result of the stack effect in your home. Of course, this can also be a result of increased humidity (which may be caused by increased airflow).

Fluctuating Temperatures

One of the strongest signs that the stack effect is at work in your home is regular fluctuations in temperature. If you notice that your home seems to blow hot and cold regularly, you should consider the fact that the stack effect might be present.

If you see any of these signs at work, you should take the time to investigate further. Better yet, you should have a professional take a thorough look at your home. A proper investigation of these signs will help a local expert figure out exactly what is causing the issues relatively quickly. More importantly, they will be able to figure out the best possible solutions for your home.

How Ohio Basement Authority Can Help

If you suspect that the stack effect may be at work in your home, we urge you to contact the Ohio Basement Authority team as soon as possible. We are one of the premier crawl space repair and encapsulation specialists in Cincinnati and Columbus, Ohio. We have helped thousands of homeowners to return their property to full health since we opened our doors in 2009, and have built a stellar reputation for efficient and high-quality services.

If you have concerns about your property, you can contact us directly or book a free inspection appointment online. These appointments are the first step in any repair process, but they carry no obligation to book repairs with us. They are, however, necessary for our team because they allow us to assess the situation, get an idea of the work that is needed, and formulate a reasonable estimate of costs. Our local experts will provide you with a written quote so that you can make an informed decision as to what is best for your home.

Our crawl space experts can help you

Request free inspection
Request free inspection
Our crawl space experts can help you

OBA map with Cincinnati

Serving Greater Columbus, Cincinnati, Dayton, and Southern Ohio

Cincinnati Office

1270 Hillsmith Dr.
Cincinnati, OH 45215

Columbus Office
2421 McGaw Rd.
Obetz, OH 43207