How much does it cost to insulate a single room?

Insulation helps fill up cracks and cavities in your walls and ceilings, which helps stop thermal transfer. This makes your home more energy efficient and the rooms within it more comfortable and easier to heat and cool. While insulation is easiest to add to new construction, it is possible to add it to an existing room as well.

Insulating a room costs on average $650 to $1,000, with the average homeowner spending around $825 on adding blown-in insulation to existing walls and ceiling in a 10’x10’ room.

Reasons to insulate a room

If your home was built prior to the 1940s, it likely doesn’t contain any insulation inside the walls, and if it was built after that, but prior to the last 10 years, what insulation you do have may not be adequate. Insulation can also settle or deteriorate over time, and can be disturbed by pests or workmen, which can make it less effective.

Insulating a room means that less energy will be transferred through the walls and ceiling. This means that when you heat or cool this room, it will take less energy, because some of that heated or cooled air won’t be escaping through your walls. It also makes the room more comfortable to be in. So, if you have a room that tends to be very cold in the winter or very hot in the summer, or that seems difficult to heat and cool efficiently, then adding insulation can help.

Insulation can help reduce sounds coming into or leaving the room as well. If the room echoes or seems loud, adding insulation can help reduce these issues, making it more quiet as well as more comfortable.

Cost factors

There are a lot of factors that play a role in the final cost of insulating a room. The size of the room is one of the biggest determining factors, as most insulation is sold and installed by the square foot, so larger rooms will cost more to insulate.

The type of insulation will also play a role. Some insulations will cost more than others. Some insulation will also require you to open up the walls to install them, while others can be added through small holes cut into the wall. Cutting and patching a hole ($20 - $30 per hole) will cost considerably less than removing and replacing the drywall ($1,500 - $2,000). If you’re in the middle of a renovation, you may be able to insulate at the same time using a less expensive method, while adding insulation to existing walls will always cost more, even if you don’t replace the drywall.

In addition, when walls are opened, you may discover that there is mold, old insulation that may contain asbestos ¹, or you may discover that other repairs are required. Any of these instances will impact the total cost of the job.

R-Value

When insulating, you need to pay attention to the R-value of the material you’re installing. R-value refers to how well the material resists the transfer of energy. Higher R-values mean better insulating properties, while lower R-values mean fewer insulating properties. Typically, R-value can be increased by increasing the thickness or the amount of insulation, but different insulations can also have different R-values.

The R-value you want to have in your home will be determined largely by where you live. The country is divided into zones, with the hottest, southern-most states in zone 1 and the northern states in zone 7. Each has a suggested R-value range for walls, and types of insulation to consider.

Keep in mind that it is possible to layer insulation to get the best results. For example, if you already have batts, it’s possible to add blown-in insulation to them; you do not need to remove them to get better R-value.

Types of insulation

There are several different types of insulation. Many of them can overlap, meaning that they can each be used in several areas, but some may be best for one area over another. They also have varying R-values, costs, and difficulties in installation.

Labor

The installation process and what the labor looks for your insulation will differ based on two factors: if your walls are open, such as in new construction, and what type of insulation you are using.

In new construction, labor costs will be lower for the insulation installation, because the walls are fully accessible. The areas being insulated can be easily seen and visualized, and you have more choices for what insulation you’re using. If the walls are closed and the insulation is being added to an existing home, then your choices are more limited. Batts and foam cannot be used without fully opening and exposing the walls. If you chose not to open the walls, you are limited to a type of blown in insulation.

For most homeowners looking to add insulation to an existing home, labor will consist of the installer cutting strategically placed holes in your walls to admit the insulation. It will be pumped or blown into your walls using a machine, usually in several places around the room to ensure good coverage. After the installation is complete, the cut section of the wall will be replaced, taped, and spackled ² over. If this area is visible, you will want to repaint the wall to help the patch blend in. Professionals typically charge by the hour to install insulation, with costs ranging from $40-$70 per hour. For a 10’x10’ room, you can expect this to take between 2-3 hours at the most, depending on how easy the spaces are to access. This makes the labor portion of the project cost roughly $100-$150 of the $650 total.

Enhancement and improvement costs

Weatherstripping

If you are adding insulation to make your home more energy efficient, you may also want to add weatherstripping. Weatherstripping goes around windows and doors and helps stop air gaps, which can lower efficiency. This project costs around $168.

Soundproofing

Insulation can help reduce noise in the room, but some rooms may need additional soundproofing with the addition of acoustic paneling for walls and ceilings. Soundproofing a room costs around $1,000-$2,500 on average.

Installing double pane windows

Another option to consider is to install double pane windows. Double pane windows help insulate this area, which can help lower energy costs. The cost of replacement windows is around $650-$1,500.

Drywall

If you choose to use spray foam or batt insulation, you will need new drywall ³ at the end of the project to cover the new insulation. The cost to add drywall to a room is around $1,500-$2,000.

Additional considerations and costs

• Some types of insulation can be installed DIY. This is most often recommended for open spaces like attics, and not interior wall cavities, which require you to open the wall.
• If you are unsure of whether or not you need insulation, you can get an energy audit done first. Energy audits will determine your biggest energy wasting areas, and can help recommend a plan of action, including insulation. An energy audit costs around $150 on average.
• Some energy efficient home improvements are eligible for rebates and tax credits. While the federal tax credit has expired, many states have their own incentive program for homeowners. Contact your local state government to find out if you are eligible for this savings.
• Be mindful of the fact that some contractors may provide estimates in inches only. This is because many insulations can be fluffed to appear fuller than they are. If this is the case, you are not getting the full R-value of that insulation. Make sure that they are insulating to the fullest extent to get your money’s worth.
• You can save some money by doing some prep work yourself, such as making sure the room is accessible for the machine, locating areas to be opened, or opening the wall yourself.

Remodeling Terms Cheat Sheet

² Spackled: A paste, composed of gypsum plaster, glue, and water, used to repair holes and cracks in plaster before painting or wallpapering

³ Drywall: Type of plasterboard, commonly used to build walls and ceilings, composed of gypsum that is layered between sheets of heavy paper