July 25, 2025
Struggling with a bedroom that won’t cool off no matter how low you set the thermostat?
There’s nothing more frustrating, especially on a muggy summer night when the heat makes it impossible to fall asleep.
The good news is that it's fixable. But the right solution depends on what’s causing the problem. It could be your air conditioner, your ductwork, your insulation, or your windows. Sometimes it’s a mix of all four.
What Makes One Room Hotter than the Rest of the House?
At Weatherization Services, we’ve been improving houses in Milwaukee and throughout the surrounding area since 2008. Over the years, we’ve seen (and fixed) it all.
Here’s what usually causes one room to run hotter than the rest, and what you can do to fix it
1. Air Conditioning Issues
Your AC is the most obvious place to start when a room won’t stay cool. Sometimes, your air conditioner is just getting old and can’t keep up anymore. Or, you might have a relatively new AC, but it’s too small to cool your entire house.
If your central AC is old or undersized, you may need to replace it with a properly sized unit. Sometimes, you can avoid replacing the whole system by installing a ductless mini split air conditioner in the problem bedroom.
2. Leaky or Poorly Designed Air Ducts
Your air ducts carry cool air from your AC to the various rooms in your house. If they’re leaky, blocked, or poorly connected, they might be able to get cool air to some rooms but not all of them.
Ductwork issues can happen in any house, but they’re especially common in older houses where new ducts were improperly installed and in additions.
If your air ducts are the problem, you might need to seal duct leaks. If larger duct repairs are needed, installing a ductless mini split AC could be a better option. A ductless AC can make a big difference in comfort without having to overhaul your ductwork.
3. Poor Attic Insulation
If your bedroom is on the second floor or right below the attic, the problem might be coming from above. On hot summer days, attic temperatures can climb well over 100°F. Without proper insulation and air sealing, that heat moves straight down into your room.
Improving attic insulation and sealing air leaks can make a huge difference in comfort.
4. Old or Leaky Windows
If your bedroom has old or poorly sealed windows, they could be letting in a lot of heat, especially in the afternoon when the sun is strongest. Single-pane windows can let heat radiate right into the room. Cracks and gaps around the seals, meanwhile, let hot outside air in while cool AC seeps out.
In some cases, sealing around the windows and adding insulated blinds or curtains can help right away. If your windows are getting old, though, it may be worth installing energy-efficient replacement windows that reduce heat gain in the summer and heat loss in the winter.
Find the Fix to Uneven Temperatures with an Energy Audit
The truth is, there are a lot of issues that can cause uneven temperatures in your house, leading to problems like hot upstairs bedrooms. Sometimes it’s one thing, like poor insulation. Other times, it’s a mix of problems.
But, it’s not always immediately obvious what the underlying problem (or problems) are. If you start going after solutions right away, you could end up spending $15,000 on a new air conditioner when sealing up a few air leaks would have done the trick.
That’s why we recommend a home energy audit. An energy audit is a comprehensive evaluation of your entire home that looks at your HVAC system, insulation, air leakage, and more. It shows us exactly what’s causing the problem so we can implement the right solution.