The Stack Effect - What It is & Why It's a Problem

Solving Basement Moisture & Air Quality Caused by the Stack Effect

Thanks to modern-day heating and air conditioning, we’re able to keep our NJ homes at a comfortable temperature all year long. But the temperature difference between the indoor air and outdoor air creates a phenomenon known as the stack effect.

The stack effect can pull uncomfortable, unclean air into your basement or crawl space and up throughout the rest of your home. Even if you never step foot in your basement or crawl space, you are breathing in that air thanks to the stack effect. You are breathing in whatever is in your basement or crawl space, whether it’s good or bad. This can include mold, dust mites, bacteria, viruses, and other contaminants.

Let's break down what the stack effect is, why it is a problem, and how to correct the issue.

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What is the Stack Effect?

The stack effect also called the chimney effect, occurs when air enters your home through unsealed openings in your basement or crawl space and is pulled upward through your home, exiting through your attic or your roof’s ridge vent.

The stack effect results from air buoyancy – a difference in indoor-to-outdoor air density that comes from temperature and moisture differences.

During the colder months, moist, cold outside air enters through your basement or crawl space. As the air begins to dry and warm, it rises up into the rest of your home. Eventually, the warm air escapes out the top of your home. The warm air escaping your home reduces the pressure in your basement or crawl space, which pulls in more cold air from outside, continuing the cycle.

What Causes the Stack Effect?

The stack effect is caused by cracks and openings in our homes. Some of these openings develop over time as pipes, nails, and other construction materials bend, shrink, and expand.

Plumbers, electricians, and other contractors also leave gaps to make room for wires and ductwork. Unsealed windows that are original to the home may also create an inlet. Unless these areas are properly sealed, the stack effect is inevitable.

Humidity Is the Culprit

The real problem occurs when there is excess humidity in your NJ basement or crawl space. The humidity creates a breeding ground for mold. And when the mold reproduces and releases spores into the air, these spores reach the rest of our home thanks to the stack effect.

Dust mites and animal dander are some of the other pollutants that can travel from our basement or crawl space to our living rooms, bedrooms, and every other room in our home.

What Causes Humidity

But what causes the humidity in the first place? There can be a number of reasons why basement/crawl space humidity is a problem in your New Jersey home. To start, there can be standing water in the basement or crawl space. The water that’s seeping in through the foundation will cause the space to become more humid.

It’s also important to know that the hotter the air is, the more moisture the air can hold. But because the air in our basements and crawl spaces is cooler, the air cannot hold as much moisture. This results in condensation, which creates the perfect conditions for mold to grow.

Problems Caused by Humidity

Indoor humidity levels should always fall somewhere between 30-50%. Otherwise, our homes become susceptible to the many problems associated with mold, including:

Physical symptoms such as watery eyes, dizziness, headaches, a scratchy throat, difficulty breathing, and more. Mold can cause upper respiratory infections and trigger allergy and asthma symptoms.
Rotting wood. This means more than just damaged wooden furniture. When left untreated, rotting wood can compromise the structural integrity of the home. It’s important to remember that our homes are largely made out of wood. So, if the wood deteriorates, the structure of your home can weaken and, in the worst-case scenario, collapse.
Musty smells. Mold and rot can create strong odors of must and mildew that can spread through your home.

Here’s the good news: Without humidity, there is no mold. So, in order to protect your home, your family, and yourself, the best thing you can do is control the humidity in your home. This is where our NJ basement waterproofers and crawl space waterproofers can help you.

The Stack Effect & Your Basement

Removing humidity from your basement can involve one or a combination of several approaches. During an on-site consultation, our NJ basement waterproofers will determine the root cause of your basement humidity problems. Here are some of the solutions we might recommend for your basement:

A French drain. This system will redirect the water that would normally seep into your basement and stay there. We’ll dig an interior trench around the perimeter of your basement. The water will enter the trench and reach the sump pump, where it will then be dispersed up and away from your home.
A basement dehumidifier. This isn’t the kind of dehumidifier you’ll find at the hardware store. We install dehumidifiers specifically designed for NJ basements. It’s important to remember that while a French drain redirects the water away from your home, it doesn’t remove moisture from the air. In order to protect your air quality and your home from all of the other problems associated with high indoor humidity, the moisture needs to be controlled. And the best way to do that is by installing a basement dehumidifier or crawl space dehumidifier in your home.
Drill weep holes into the walls to reduce hydrostatic pressure and remove moisture from inside of your basement walls.

Basement Weep Holes

French Drain Installed

Basement Dehumidifier

The Stack Effect & Your Crawl Space

Crawl space vents are the most common entry points for outdoor air. At Blue Umbrella, we specialize in crawl space encapsulation to seal your crawl space from the outdoor air and humidity. During this process, we will seal up the vents, install a sealable crawl space door and install an impermeable vinyl liner on the floor and walls.

Encapsulating your crawl space does more than keep the moisture under control. It also creates new storage space thanks to the vinyl liner. What was once a useless dirt floor is now extra storage space that you know will stay dry.

NJ Crawl Space Vapor Barrier Installation

Clear the Air With Blue Umbrella

We can’t prevent the stack effect from occurring in our homes. But the good news is that we don’t need to. It doesn’t matter if the air from your NJ basement or crawl space reaches your living space.

What matters is that the air is clean and safe to breathe so that by the time it reaches the rest of your home due to the stack effect, it doesn’t have any sort of negative impact on your family’s health and comfort.

If you or someone in your home experiences allergy symptoms, don’t be so quick to blame it on seasonal allergies. The real problem might be traced to your overly humid basement or crawl space.

As your local basement waterproofers and crawl space waterproofers, Blue Umbrella has you covered. Step under the umbrella and schedule an estimate for your NJ home to understand what’s happening in your basement and crawl space and, more importantly, fix the problem at hand. Learn more about our crawl space encapsulation and basement waterproofing services by contacting us online or calling us directly at 908-432-8858 today.