How to Blow Insulation into Existing Walls

Lead Image
  • 4-8 hours
  • Intermediate
  • $500-1,000
What You'll Need
Drop cloth
Stud finder
Hole saw
Cellulose insulation
Insulation blower
A friend
Safety goggles
Protective mask
Drywall tape

Blown-in insulation is a quick way to add insulation to your home. You can put it in your walls, attic, crawl space, and even under the floors. It is a very versatile as far as its ease of installation is concerned, but the one problem a homeowner can face is installing blown-in insulation inside existing walls. This is especially a concern with older homes where insulation was more of a luxury than a necessity. The following article will show you how to install this type of insulation into existing walls without removing drywall, blowing cellulose fibers between the studs.

Step 1 - Create Access

Staring down a sealed wall and needing to add blown-in insulation to it can seem like an impossible task, and even more impossible because of the mess you could make doing this yourself. Rest assured that it is actually not that hard to do and there does not have to be too much mess involved.

Place your drop cloth tight against the wall where you will be working. This will catch excess insulation and dust from the drywall. Then, use a stud finder and make a mark at each stud. Cut a two-inch diameter hole in the drywall with the hole saw and carefully remove it. Don't lose this piece as you will use it again later. Try to place the holes close to the top of the wall. This allows the cellulose to fall naturally, settle, and pile.

Step 2 - Install Blown-in Insulation

You will need a friend to help with this part of the project. Place the head of the blown-in insulation hose into the hole and continue to let it drop towards the bottom. Wrap and hold a rag around the hose where it touches the wall, and have your friend turn the blower on. As the cavity fills, pull the hose out of the hole. Go slow to ensure the cavity gets packed tight. As soon as you feel resistance near the top of the cavity have your friend turn the insulation blower off. Carefully remove the hose and repeat with every hole you made. It is very important to work methodically and carefully.

WARNING: Always use protective glasses, gloves, and a protective mask while blowing in insulation.

Step 3 - Seal the Holes

You have just filled your walls, but now you have a bunch of holes in the drywall. You cannot leave it like this, so it has to be patched up. Saving the drywall discs you cut in step one is what allows you to make this an easier job than it seems. Try to keep the discs in order of cutting because if you made a slip of any kind the piece may not fit in other portions of the wall. Carefully slide a disc into the hole you cut. Have your friend hold the disc in place as the blow insulation may push against it. Apply drywall tape to secure it and then finish the job with spackle. Afterward, you will obviously need to repaint the wall for a uniform look.

With that, your walls are now insulated and patched. Now you can sit back and watch how much you save on your energy bills each month.