Why Is My Basement So Hot?

Learn why your basement can be warmer than needed and how to fix than

Written by Camilla Moln. Updated on Why Is My Basement So Hot

Have you ever noticed that your basement gets hotter than the rest of the house? It may happen during the winter months more often but in summer, you can also feel that your basement temperature is significantly higher than the air temperature upstairs in the rooms.

Why does it happen? Why is my basement hot?

Today we will do our best to find answers to these questions. You will learn about a few factors that can lead to the escalation of your basement temperature.

Also, we will tell you what methods can be used in order to fix that. In addition, you will learn plenty of other useful information on this subject, such as whether you need to dehumidify your basement and what dehumidifiers are best for this purpose.

Why Is It So Hot In My Basement?

If you have a hot basement in your house, there can be several reasons for that. The main reason a basement may start feeling hotter than the rest of the house is that there is a leak somewhere.

You may also have water underneath your home, which can cause a hot and humid climate in your basement. But these are not the only factors that may lead to a higher temperature in your basement.

Why Is It So Hot In My Basement
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You Have Exterior Insulation

If your home has a layer of exterior insulation wrapped around its walls including the basement, then this can be one of the reasons why the air in your basement feels way hotter. It happens because insulation protects your walls from losing heat but at the same time, it prevents cold air from getting in!

So as a result, in a basement with exterior insulation, any temperature changes will be slowed by the thick foundation walls. This means that, in the summer, the basement will often feel cooler than the outside since it takes the summer heat a very long time to get to the basement.

On the other hand, during the winter, the basement will be warmer than the outside because warmth is leaving it much slower and cold air can’t easily get in.

You Have Exterior Insulation
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Your HVAC Ducts Have Unsealed Connections

If your HVAC ducts have unsealed connections (especially if these connections are located in the basement!), the temperature down there will surely be higher and the rest of the house will be colder.

The reason is that when HVAC connections are in the basement and they are unsealed, hot air is escaping into the basement, raising its temperature. Instead of being transported to higher floors, warm air is leaking down into the basement.

As a result, these floors are receiving less warm air in comparison to what they would be receiving if the ducts were sealed. Unsealed HVAC ducts in the basement will always mean a surplus of warm air in the basement and, respectively, a shortage of warm air in the rest of the rooms in your house.

You May Have Air Leaks in the Furnace’s Main Trunk

A furnace’s main trunk is the largest duct that is leading out of the furnace. This duct carries warm air to the rest of the house. So if there is an air leak from the furnace’s main trunk, especially from the largest part of it in the basement, this will certainly end up in your basement feeling hotter than the rest of the house.

How To Get More Heat In The BasementHow To Get More Heat In The Basement

And since hot air from the leaks in the furnace gets accumulated in the basement, the rest of the house is getting colder because of the leakage.

Your Walkout Basement Has Glazing

If you have single glazed, poorly installed, or open-glazed windows in your basement, note that all of them are not very efficient at keeping your indoor temperature stable.

Such windows often lead to either heat loss or heat accumulation. As a result, during the winter, you will most likely be losing heat and in the summer, your basement will gain heat instead.

Ask A Home Builder: What Is A Walkout Basement?Ask A Home Builder: What Is A Walkout Basement?

This absorption of heat and further radiating it into your basement may lead to a significant rise of the basement temperature, making your basement feel much warmer than if it had double glazing.

We described the most common reasons for heat in your basement so that you have a better understanding of why the air may feel way hotter there.

However, no matter the reason, you need to figure this issue out as soon as possible! Considering that excess warmth may lead to moisture which will later result in mold, structural problems, and even health concerns, your hot basement has to be fixed.

How to Fix a Hot Basement?

So, if you have a hot basement, you definitely want to know what to do about it. Simply ventilating is not always a good option, considering the possible reasons for the heat boost.

So we are going to suggest you a few alternative coping strategies instead. With their help, you will be able to act quickly and fix exactly the issue that caused heat gain.

How to Fix a Hot Basement
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What to Do If You Have Problems With Insulation?

If you have outdoor insulation and it is the culprit of your extremely hot basement, you can try a couple of solutions to fix that.

Try leaving the basement door open most of the time. By doing this, you will allow the excess heat to rise and spread through the rest of the house

Install fans in your basement. They will circulate the air, helping in moving it from the basement to the rest of the house

What to Do If the Reason Is Your HVAC Ducts?

If your basement is way too hot due to the duct leak, the first thing to do is to use duct sealing tape (also known as aluminum foil tape). Just apply the tape to the spots where the duct leaks are.

Is it too hot in the basement due to a leaky duct

Duct sealing tape is easily available both online and in a store, it’s easy to use, and it’s not as messy as other methods. But it is not perfect, of course. The aluminum tape will not last long, and also, it does not give as good results as other methods.

You can also use another method, which is mastic duct sealant. It is cheaper, more durable, and works better than duct sealing tape. All you need to do is to apply the mastic duct sealant to the leaking spot with a paintbrush, as well as a caulk gun (if you prefer that option). The liquid sealant will dry and create an air-tight seal.

Are there any gaps near the heat exchanger

Finally, you can always have a professional seal your leaking ducts for you. This method will be the most expensive, of course, but on the other hand, it will be the most efficient and durable.

What to Do If the Reason Is Your HVAC Ducts

What to Do If You Have Leaks In a Furnace?

The good news is that sealing leaks in a furnace can easily be done by yourself. You are not supposed to hire professionals for that, although professionals will do the job faster and more thoroughly for sure. To seal furnace leaks, opt for one of the two approaches:

For smaller gaps, use regular silicone caulk. If you have gaps near the heat exchanger, make sure you are using a silicone caulk that resists high temperatures since any other type can melt!

For larger gaps, use a foam-type sealant. After you apply it, the sealant will expand, closing larger gaps. Besides, it can be shaped and painted to match your furnace!

Try to Air Condition Your Hot Basement

Although it is not technically required and it should not be your go-to method, it can be a good idea to air condition your hot basement. Like that, your basement won’t feel muggy and you will avoid mold and mildew growth.

Air conditioning is also great for making your basement safer for your belongings as a storage place. When your basement is air-conditioned, you can safely store important items down there without being afraid that they will become damaged by moisture or heat.

Try to Air Condition Your Hot Basement
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Cool Your Basement Down Without the Air Conditioner

As an option, you can combat excessive heat in your basement with the help of a portable air cooler. This device will cool down your basement without the need for air conditioning.

Like that, you will lower the temperature and also prevent too much humidity from forming. Since there are brands out there that sell air coolers specifically designed for basements, you won’t have trouble finding the most suitable model for yourself.

Now you know what can lead to an extremely hot basement and what steps should be taken to fix this issue quickly and effectively.

Is It Normal For a Basement to Be Hot?

This is the first question people ask when they face this problem with their own basements. Is it normal that my basement feels like a sauna?!

No, it’s not common for a basement to feel hot.

Of course, the temperature in your basement will feel slightly different from the rest of the house, but this difference shouldn’t be that big. Typically, your basement should be just a bit cooler than other rooms in the house.

Depending on the weather outside, the normal temperature in a basement will vary throughout the year. But the average temperature levels will be the following:

In winter, you should keep your basement between 55 and 60 degrees

In summer (or if you live somewhere warm), you’d better keep your basement under 80 degrees

But of course, if you feel comfortable keeping your basement in the 60s or 70s all year round, you certainly can do that! However, regardless of the weather or your personal temperature preferences, you should never let a basement get too warm! If you do this, problems will start appearing very soon.

What is the correct temperature in the basement

So, today we told you about the reasons that can make your basement feel way too hot. Now you know what can make your basement temperature rise and what you should do to fix that.

Also, you are now aware of an average temperature range that is considered normal for basements. And since you know how to fix excessive heat in your basement using different methods, it will be quite easy for you to cope with this issue should it appear in your home.

Is It Normal For a Basement to Be Hot
AllaSerebrina via VistaCreate

Frequently Asked Questions

⭐What is the maximum temperature allowed for a basement?

There’s actually no such thing as “allowed temperature”. Unheated basement temperatures are not likely to fall below 40-50°F, for example.

⭐What is the ideal temperature for a basement?

In the summer, try keeping your basement at 80 F or lower to help suppress humidity and mildew. Ideal basement temperatures are 55 F to 60 F in winter, and less than 80 F in summer.

⭐Should I put a thermostat in my basement?

For the right place to put your thermostat, choose a room that's commonly used (like the living room or main hallway) rather than an empty, drafty one like the basement. A room on the very top floor is also not suitable since it may be hotter. Also, avoid placing your thermostat near windows or doors.

Written by
Camilla is an experienced Consultant with more than 20 years of preparing professional articles for numerous online resources. She has done a tremendous job and has learned a lot during her career. Camilla will advise you on the latest trends and give amazing tips on how to decorate a house.
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