Lowe's Home Improvement
FREE PARCEL SHIPPING on Qualifying Orders

Insulate Exterior and Interior Walls

Insulate Exterior and Interior Walls

Save energy and money by insulating your interior and exterior walls properly. You can do it yourself with this helpful how-to guide.


Insulate Exterior Walls

R-Value Chart

Since the walls in most homes represent more exterior surface area than the floors or ceilings, they also present more opportunity to lose and gain heat. Protect yourself and your home from the cold of winter and the heat of summer with adequate insulation. Although cellulose insulation can be used to insulate exterior walls, it is best to leave that job to the professionals. However, installing roll insulation in interior walls is a simple project most homeowners can complete themselves.


Step 1

Determine the R-value required in your area by using the chart below or contacting your local contractor or building inspector.

 Zone Roofs Walls Floors
 1 R49 R28 R25
 2 R49 R22 R25
 3 R49 R18 R25
 4 R49 R18 R25
 5 R49 R18 R25
 6 R49 R18 R25

Step 2

Measure the distance between wall studs to determine whether you need 15-inch or 23-inch-wide insulation.


Step 3

Use our insulation calculator to determine how many square feet of insulation you need.


Step 4

Start at one end of the wall and place insulation between the studs with the vapor barrier facing the interior of the room. Staple the insulation every 6 inches to hold it in place. The insulation should fit snugly between the studs. If you need to cut the insulation, turn the faced side up, compress the insulation with a straightedge and cut along the edge with a utility knife. Faced insulation has extensions on the sides that allow you to staple the insulation to the edges of the wall studs.


Step 5

Continue installing the insulation until the entire wall is covered.


Step 6

Stuff small pieces of insulation into areas around obstructions. Use a broom handle to stuff the insulation into other hard-to-reach places.



Insulate Interior Walls

Another way to cut your energy costs is to add insulation to your interior walls. Insulating a finished wall can require a few more steps than insulating a wall that is open, but the time it will take will be worth the energy savings. Adding insulation to your interior walls can also enhance your home's privacy, keeping sound from traveling from one room to another.

You can rent the blower from Lowe's, or get it free for a day with the purchase of 25 or more bags of cellulose insulation.

Step 1

Determine the R-value required in your area by using the chart above or contracting your local contractor or building inspector.


Step 2

Use our insulation calculator to determine how many bags of insulation you need.


Step 3

Find the studs in the wall that you are going to insulate using the stud finder, and mark halfway between each stud, approximately 6 inches down from the ceiling. Continue all the way across the walls you are insulating until you have marked this point between every set of studs.


Step 4

With your hole saw, cut out a circle that is slightly larger than your insulation blower's hose. Save these pieces, so you can use them to repair the holes later. You might want to mark them to help you figure out which piece belongs to which hole.


Step 5

Set up the blowing machine according to the manufacturer's instructions, and begin blowing the insulation into the wall section. When the insulation reaches the appropriate depth in this wall, pull out the hose, and move to the next hall. Repeat this process until you have filled each section.


Step 6

Next, you should patch your holes. Spread compound around the edges of the holes you cut out and fit them into place using a little pressure.


Step 7

Smooth compound around the edges of the patched hole, and put drywall tape over all joints with the joint knife. At the end of each joint, press the edge of the knife blade in firmly, and use it as a straight edge to tear off the tape. Sand when dry.


Step 8

Using a wide joint knife, spread a smooth, thin layer of joint compound over the repaired area. Extend beyond the damaged part, and feather the edges out to the surrounding wall.


Step 9

Wait at least 24 hours. The compound should be dry before you sand it. Use a fine-grade drywall sandpaper on a sanding block. You may have to repeat steps 8 and 9 to achieve the desired results.