A too-hot upstairs can feel awful to live in. If your upstairs can’t get cool in the summer, you need to read this.
If you clicked on this article, you’re probably here because… well, you’re miserable. It’s hot outside, yes, but more importantly it’s hot inside, especially on the top floor of your house. Hot upstairs, cold downstairs = bad news.
But here’s some good news: Uneven cooling is a fixable problem—even if you have an older house.
In this guide, we’ll take you through the most common causes of a hot upstairs, show you how to diagnose each issue, and then give you some possible solutions.
Here’s what we’ll cover:
- How to troubleshoot a hot upstairs
- How lack of insulation can cause a hot second story
- Telltale signs that your HVAC is the problem
- The best AC system for a cool, fresh-feeling upstairs
- FAQs about cooling your second floor
- How to get home upgrades for no (or very little!) upfront cost
Upstairs too hot? Bad airflow on the second floor? Here’s how to troubleshoot the source of the problem.
Here are the 5 most common reasons why your upstairs is too hot.
FYI: We’ll go from the least likely reason to the most likely reason. But more than one issue can be happening at a time, so keep an open mind as you go through the list!
- Problem 1: Your HVAC ducts aren’t working correctly
- Problem 2: You’ve got one thermostat for your entire house
- Problem 3: Your house is full of holes—also known as air leaks
- Problem 4: Your roof and attic are full of hot air
- Problem 5: Your AC isn’t up to the challenge.
Ready? Let’s dig in.
Problem 1: Your ducts aren’t working correctly.
Let’s start with the favorite subject of every homeowner coupon book everywhere: the ductwork in your house.
Your ductwork is the pathway by which cool air reaches every part of your home. But that’s an ideal case.
In reality, ducted systems are prone to design and leak issues. So if you have an older house or ductwork that hasn’t been serviced in a long time, it’s possible that the cold air being pushed through your second-floor ductwork is getting lost or warmed while in transit.
It’s possible that the cold air being pushed through your second-floor ductwork is getting lost or warmed while in transit.
How can you tell if your ductwork is causing a too-hot upstairs?
First, check to be sure your AC is running and set to “cool”—and that cool air is actually coming through the vents on your first floor. Then, place your hand near the floor vents on the second story of your home.
If you don’t feel any cold air coming out, that’s a huge sign that your ductwork might be the issue (or that your AC just isn’t big enough to service your whole house—but more on that later).
To confirm your diagnosis: Another telltale sign of aging or insufficient ductwork is a dust problem. If you’ve been faithful to change your HVAC filters and there’s still a constant layer of dust over everything, the ductwork might be your culprit.
You can also grab a flashlight and take a look inside your ductwork for any visual signs of decay. Look for old, cracked seals on the ducts or for anything that looks rusty, crushed, or kinked. If something doesn’t look right, it probably isn’t.
What’s the fix?
If you suspect ductwork is causing your upstairs to be too hot, you’ve got a few options.
One solution is to call in a professional duct team for cleaning and maintenance.
Also, if it looks like only the seals are bad, it’s possible to seal ducts yourself using mastic sealant or metal tape. (To be clear, we don’t recommend this unless you’ve got DIY energy to burn, a good health insurance policy, and a lot of time on your hands.)
Keep in mind that cleaning and maintenance may not cut it, especially if you have an older home, where ductwork is often not up to code. It’s often best to replace the ductwork entirely (or, more conveniently, install a ductless mini-split air conditioner, which circumvents the problem entirely).
Another thing to be aware of? Duct problems don’t exist in a vacuum. If you live in a house where the ductwork has decayed, it’s likely you’ve got some other HVAC issues which are contributing to your indoor heat problem. (If you’re eligible for Sealed, you can get a free expert consult to find out.)
If you live in a house where the ductwork has decayed, it’s likely you’ve got some other HVAC issues which are contributing to your indoor heat problem.
So! Let’s move on to the next possible issue.
Problem 2: You’ve got one thermostat for your entire house
If your entire house is controlled by one thermostat—and it’s on the first floor—then your AC system doesn’t even know that it’s hot upstairs! Thus, the thermostat will happily turn off your AC when the first floor is cool while the people on your second story swelter.
How can you tell if your thermostat is the reason your upstairs is so hot?
If there’s only one, traditional, boring thermostat that controls the HVAC for your entire home, it’s probably part of the problem. (Sorry for the shade, but thermostat tech really has come a long way.)
What’s the fix?
The solution is pretty straightforward: If you want even cooling throughout your house, you need more than one thermostat (or at least one thermostat that’s capable of sensing temperature changes on multiple floors).
How many thermostats? Well, at least one thermostat per floor is ideal, but it’s also possible to find zoning thermostats that can sense temperature changes on multiple floors and adjust the AC accordingly.
Note, though, that even the smartest thermostat is dependent on the quality and efficiency of your AC unit. So the most comprehensive solution is to install an AC system with smart thermostats and zone-by-zone cooling (so that every room in the house feels incredible).
Problem 3: Your house is full of holes—also known as air leaks
Most houses are full of tiny holes and gaps which allow air exchange with the outside—and hot air is drawn in through those holes and then rises to the second floor… where it makes you miserable.
How can you tell if air leaks are causing a hot upstairs?
If your house isn’t recent construction and you have no record of your house being professionally air sealed, there’s a good chance that it’s full of holes. It’s that common of a problem.
EnergyStar.gov estimates that between 25–40% of the money Americans spend to heat and cool their homes is lost because of air leakage problems (1).
What’s the fix?
The detailed answer? Identify where those holes are (keep in mind: there are thousands). Then you’ll need to use caulking, weatherstripping, and/or spray foam insulation to seal up the gaps.
The real, recommended answer? Get your house air sealed by professionals.
Air sealing is one of those projects that sounds like a DIY project, but turns into the ninth circle of Homeowner Hell as you kneel in the corners of the attic and try to maneuver spray foam insulation around a family of extremely displeased spiders.
Problem 4: Your roof and attic are full of hot air
If your roof and attic area is uninsulated (or underinsulated), heat will seep in through the roof and make it ridiculously hot on the second floor. No bueno.
How can you tell if an underinsulated attic is causing a too-hot upstairs?
Peek into your attic. If you don’t see any insulation (or if the insulation looks old or is crumbling) or if you see the rim joists peeking out from your insulation (they’re the big planks of wood that run horizontally along your attic floor), you’ve got a thermal boundary problem.
When you properly insulate your roof, you create a thermal boundary between it and the air outside, keeping outside air out and inside air in.
What’s the fix?
Insulate your attic—the right way.
When you properly insulate your roof, you create a thermal boundary between it and the air outside, keeping outside air out and inside air in. Creating the optimum thermal barrier in the attic is particularly crucial because your roof is where much of the interior warmth escapes during the winter and outside heat enters during the summer.
By the way, if your attic is uninsulated, the summertime temperatures up there can reach up to 150 degrees. You can imagine that situation isn’t great for keeping your living spaces cool.
Also, don’t forget: If your attic isn’t properly insulated, chances are good that it also hasn’t been air sealed recently. So don’t forget to do that, too! (You can also take a super-speedy quiz here to see if you’re eligible for expert air sealing and insulation at no or very little upfront cost.)
If your attic is uninsulated, the summertime temperatures up there can reach up to 150 degrees.
Problem 5: Your AC isn’t up to the challenge
This is the big one, so brace yourself:
Even if you’ve air sealed and insulated your house, and even if you have multiple thermostats, an old or inefficient AC unit will make your whole house feel less comfortable—and will also waste a ton of energy.
How can you tell if your air conditioning is why your upstairs is so hot?
Here are the most common indicators that your AC isn’t up to the job (see when to replace your air conditioner for complete list)
- Your AC system is more than 10 years old. They’re not meant to last forever!
- Your energy bills spike in the summertime. It’s normal for energy usage to fluctuate somewhat. It’s not normal for your summer energy bill to skyrocket.
- The AC is running constantly. If your AC is always on, it’s struggling.
What’s the short-term fix?
The most common temporary fix is to install some extra air conditioning (usually in the form of window units, but some homeowners prefer portable units).
This is definitely a short-term solution, but—we get it—it can be tempting to leave it as a long-term solution. Two air conditioners can be more energy-efficient than one, especially if your main AC is having trouble cooling the entire house. And if your upstairs is small (or if it’s just one or two upstairs rooms that are too warm), adding supplementary portable or window units to help your main AC system can work—for a while.
That said, there are some significant cons to this strategy.
Having a bunch of extra AC units is… well, kind of annoying. Each one will need to be installed and/or moved every year—and every additional AC unit will need to be vented to the outside separately (especially annoying for portable, in-room units that will need to be vented by a hose).
You’ll also need to manage the temperature on each unit manually. That’s a challenge which is easy to overlook, but—trust us—getting up in the middle of the night to turn the AC up or down can get pretty irritating.
Also, while installing small units might appear to be like a less expensive strategy than getting a whole new AC system, you might not be saving as much as you think when you consider the cost of purchasing and maintaining the units as well as the energy cost of running additional appliances.
Frankly, in the long term, throwing in supplemental air conditioning probably won’t save money at all. Installing extra AC units only treats the symptoms of the problem. The real problem will still be there, and you’ll need to fix it—and pay for that fix—eventually.
What’s the best fix?
You guessed it. By far, the best fix for an underperforming AC unit is to… replace it.
Air conditioning has come a long way in recent years, and you’ll be amazed at what a difference a custom-designed and energy-efficient AC system will make in the comfort of your home. (With Sealed, you can get a new, customed-designed AC system and expert installation for no—or very little—upfront cost.)
Of course, there’s a lingering question here: What kind of air conditioning HVAC system is best at making a whole house feel incredible?
We thought you’d never ask.
The best AC system for a cool, fresh upstairs? We’ve got the top pick.
Meet the Tesla of HVAC: The heat pump.
(Heat pump ductless options are also known as mini-split AC).
Heat pump AC systems are the best, most energy-efficient cooling technology presently available.
Don’t be fooled by the term heat, either! They got their name because of how they function: Essentially, heat pumps remove heat energy from your house and transport it outside, so that your house stays cool and fresh and at the perfect temperature. All year, on all floors, and no matter what the outside weather.
This isn’t new tech, to be clear. Your current air conditioner works the same way (and, actually, so does your fridge).
What’s revolutionary about heat pumps is that they can also reverse the process—that is, they can capture heat energy from the outside air and transfer it inside your home in winter.
That means that heat pumps are not only air conditioners, they’re heaters. And they also purify and dehumidify the air inside your home.
Basically, they’re a complete HVAC solution. One system that does it all. Only one system to think about. The dream!
And they do it all at a significant energy savings—heat pumps can be up to 3 times more efficient than traditional HVAC systems.
But will heat pumps fix your upstairs-is-a-sauna problem? Absolutely. The beauty of heat pump technology, too, is that it interfaces beautifully with smart thermostats for even, comfortable temperatures everywhere in your home.
And if you opt for a ductless system, you’ll get zone-by-zone cooling for super-precise temperature control of every part of your house. (In other words, you can expect both an extreme increase in comfort and a major reduction in family thermostat arguments.)
The list of advantages goes on. Yes, we’re big fans of heat pumps. But we’re not the only ones. Heat pumps are becoming standard in many countries of the world, such as Sweden, Japan, and New Zealand.
Any cons to heat pumps?
The worst part about heat pumps is the hassle of getting one installed, finding a reliable contractor, organizing the project, and paying for it.
Also, while heat pumps are by far the most impressive HVAC technology on the market, they’re not magic. You’ll need to make sure that your home is properly air-sealed and insulated so that the air you pay to heat and cool stays in your home!
Luckily, Sealed takes care of all of that. We’ll look at your specific situation and design a whole-house solution to make your house feel better—365 days a year.
And if you don’t need a new AC system, don’t worry: We don’t do cookie-cutter solutions. One of our experts will look at your specific situation and let you know what will work for your home. So you can proceed with confidence.
Frequently Asked Questions
Feel free to scan through the Q&A below, or use the quick links below to jump ahead.
- How do you evenly cool a two-story house?
- How can I make my second floor cooler?
- How do you get airflow to the second floor?
- How can I reduce the heat in my two-story house?
- What to do if air conditioning is working downstairs but not upstairs?
How do you evenly cool a two story house?
- Make sure the house is sealed and insulated. This will help keep cool air in and hot air out.
- Repair your existing AC or get an AC unit that is properly sized for the house. An undersized unit will struggle to keep the entire house cool, while an oversized unit will cool the house quickly but waste energy in the process.
- Consider a heat pump AC system. Heat pump AC systems are the most energy-efficient cooling technology available and can effectively cool a two story house—and drastically cut down on energy waste.
- Install a smart thermostat. A smart thermostat can help you evenly cool your house by allowing you to control the temperature on a zone-by-zone basis.
- Work with a reliable contractor to get the job done right.
(Sound intimidating? Contact Sealed. If your house is eligible, you’ll get a professional upgrade plan—and expert installation—for no upfront cost.)
Whole home solutions designed by Sealed can reduce a home’s energy use by up to 50%.
How can I make my second floor cooler?
First, if your second floor is blisteringly hot, it’s likely that your house (especially your attic!) isn’t properly sealed and insulated. Get your house professionally insulated and air sealed, and you’ll likely be surprised at how much better it feels inside.
Another common culprit: An underperforming air conditioning system. If your AC is old or poorly designed, it’ll struggle to cool every part of your house. A short-term solution is to get it repaired (if there’s something that’s fixable!) or supplement your air conditioning with smaller units, but that won’t solve the real problem. The best solution is to install an air conditioning system that’s energy-efficient and expertly designed to cool your entire home.
(Those are two of the most common culprits, but be sure to visit our troubleshooting guide above to get a better picture.)
How do you get airflow to the second floor?
If your house isn’t getting good airflow to the second floor, check for the obvious culprits first: Are all the vents/registers open? Does any ductwork on the second floor look clean and well-sealed? Is the HVAC filter clean?
If those things all check out, then it’s likely your air conditioning system needs an overhaul (or if you don’t have air conditioning, it’s time to get some!). A short-term solution might be to install some temporary AC units or extra fans (this can be a good fix while you’re working on a longer term solution, especially if your upstairs feels miserable).
The best solution: Get a custom-designed air conditioning system that will make your house feel amazing. (The good news, too, is that you might be able to get one for no upfront cost.)
How can I reduce the heat in my two-story house?
Here are the long-term fixes to reduce heat upstairs:
- Get your house professionally air-sealed and insulated.
- Get an air conditioning system that’s energy-efficient and designed for your specific needs. (Heat pumps are excellent for most homeowners. Learn more here.)
Here are some short-term fixes to reduce heat in a two-story house:
- Use ceiling fans or stand-alone AC units to cool and circulate air
- Keep blinds and curtains closed during the day
- Avoid using appliances that generate heat during the hottest hours of the day
- Use a dehumidifier to lower the humidity in your home
- Take advantage of cross-breezes by opening windows on opposite sides of the house on a cool morning
- Use reflective window film or shades to deflect sunlight and heat away from your home.
What to do if air conditioning is working downstairs but not upstairs?
If the second floor of your home is not receiving adequate ventilation and cooling, check for common culprits first: Any unsealed ductwork on the second floor? Are all the registers (also called vents) open? Is your AC filter still adequate or does it need to be replaced?
If you don’t find any obvious problems, then it’s time to do some real troubleshooting. You can tap here to read the complete guide above, but, in short, here are the two most common problems you’ll probably need to address:
- Your house needs to be professionally air sealed and insulated
- Your AC needs an update
Fix those two problems (or have Sealed fix them for you) and your house will feel amazing. Year-round.
If you’re miserable right now and you need to buy time, there are a few steps to take that will lessen the upstairs problem in the short-term.
- Turn ceiling fans to high—and make sure they’re circulating counter-clockwise to create a cooling breeze
- Use box fans and portable air conditioners to strategically cool small areas
- Keep upstairs blinds and curtains shut during the day
- Open windows on opposite sides of the house for cross breezes
Take a quiz. Fix your upstairs problem.
Okay, so a quiz isn’t an instant fix to a hot upstairs.
But this easy, 2-minute quiz will tell you if your house is eligible for a Sealed home upgrade package—which comes with a custom climate control plan designed by an HVAC expert as well as installation by trusted and vetted professionals.
We’ll do all the heavy lifting to make your house feel amazing, and we take all the guesswork and hassle out of finding the right contractor, negotiating pricing, and managing the project. All you need to do? Enjoy it when we’re done.
Even better: Your home can get a Sealed makeover for no—or very little—upfront cost. It’s a simple system that works beautifully.
If I don’t have to spend any extra money to get a huge improvement to my home, it’s just a no brainer at that point.Scott R., Sealed Customer
Need another reason? Whole home solutions designed by Sealed can reduce a home’s energy use by up to 50%.
So you can say goodbye to energy waste and hello to feeling incredible in your home.