Why Are Some Rooms Colder Than Others? 7 Causes and Solutions

Your home's HVAC system should heat each room equally. But you may notice that certain areas of your home, such as the bedrooms upstairs, or that spare room near the back of the house, are much colder than others. Why are some rooms colder than others? There are numerous possible reasons; here's how to identify and fix the most common ones.

1. Closed Air Vents

If you have a forced air heating system, warm air travels through ductwork and enters each room through a vent. Sometimes, those vents can be closed or otherwise blocked, keeping the warm air from getting in and making that room much colder than other parts of your home.

How to Fix It

Take a look at the air vents in the rooms that are colder. There should be a lever on one side that lets you open the vent. If the lever is in the closed position, try sliding it to open the vent. 

It's also worth taking a look at anything that's in front of the vents. For example, if you've set a couch or bookshelf directly in front of the room's air vent, the furniture can block the airflow, affecting the temperature. Try rearranging the furniture to help warm things up.

2. Dirty Filters

The filters in your HVAC system help to keep dust and debris from blowing into the room. Filters don't last forever, and over time become dirty and covered in dust. 

An old, dirty filter doesn't work as well as it once did and can actually keep warm air from getting into the room.  

How to Fix It

This is another simple fix: Replacing the dirty air filter will help improve airflow, making the room feel more comfortable. It's a good idea to get in the habit of replacing air filters regularly. During the heating season, that can mean getting a new filter every month, depending on how much you use your heating system and how much dust your filters trap.

3. Dusty Ductwork

Similarly, the ducts that deliver warm air to each room can collect dust and debris over time, making them less efficient and leading to uneven heating. 

How to Fix It

Cleaning your home's ductwork will remove the built-up dust and debris, improving airflow. A local HVAC professional should be able to do the job for you.

4. Inadequate Insulation

It could be that warm air is getting into each room, no problem. However, once it's there, it's leaving quickly, making the room feel much colder. 

If that's the case, inadequate insulation could be the problem. Older homes often don't have the insulation needed to keep warm air from escaping during the winter, and unevenly heated rooms are a common sign of that. Other signs of a poorly insulated home include high heating bills and walls that feel cold to the touch.

How to Fix It

Adding insulation to rooms that don't have enough will help to keep warm air in and reduce temperature variations throughout your home. An insulation contractor can help you determine how much you need and the best type of insulation for your home.

While it does cost an average of $1,850 to add insulation, you may qualify for a federal tax credit to help offset the cost.

5. Drafty Windows and Doors

Put your hand by the window or an exterior door in a room that feels chilly. If you feel a draft, that could be contributing to the colder temperature in the room. Inefficient windows can contribute up to 30% of heat loss in homes, according to the Department of Energy.

Windows and doors aren't the only places where warm air can escape from a room. Air can also seep out around electrical outlets and light switches. 

How to Fix It

You have a few options for blocking drafts. Caulking around the window and door frame can be a quick way to block the drafts and keep the warm air inside. 

Another option is to replace the windows of your home with more energy efficient models. New windows can increase your home's value while reducing your heating bills. Not to mention, they'll help to make your home more comfortable overall.

6. Mis-sized Ductwork  

Ductwork isn’t one size fits all. The size of your home, the number of windows in each room, and even the number of people living there all determine the right duct size. 

Occasionally, the ductwork in your home will either be too large or too small for the space. A common sign of mis-sized ducts is unevenly heated rooms. If the filters aren’t dirty and the vents aren't blocked but you don't feel much air coming out of a vent when the HVAC is running, the size of the ducts can be to blame.

How to Fix It

Replacing ductwork is the way to go, but this isn't a DIY project. Your best bet is to have an HVAC professional evaluate your existing ductwork and calculate the right sized system for your home. The cost to replace ductwork depends on the size of your home and the location of the ductwork. 

7. Mis-sized HVAC System

It may be that your home's ducts are perfectly sized, but the HVAC system is either too large or too small, leading to unevenly heated rooms. 

When installing an HVAC system, a contractor should pay attention to your home's size, the climate in your area, and other factors such as ceiling height and the number of people living in the home. 

How to Fix It

You may need to replace your entire HVAC system if the unit you currently have is too big or small. This isn't something you can tackle on your own. Instead, you'll want to hire a pro to both calculate the appropriate system size and to install the new HVAC equipment.

Another option is to consider a zoned HVAC system. This can be a good idea if you've built onto an existing home and are currently dealing with cold rooms in the addition.

When to Call a Pro

It may be that all you need to get your home's heating in balance is to change a filter or open an air vent, but some fixes are more complicated than others. You'll want to hire a local HVAC repair pro if you need to make repairs or clean or change the ductwork.