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Installing Blown-In Insulation

Materials List
Loose-fill insulation
Dry wall compound
Expanding foam sealer
Tools List (click item to shop)
Insulation blower
Hole saw drill bit
Stud finder
Tape measure
Step ladder
Wide putty knife
Bread knife
Easy2 Home Improvement
Insulating an Unfinished Attic

Applying Temporary Weatherstripping
Applying Permanent Weatherstripping
Installing an Attic Fan

IMPORTANT: Read this before you start


Have you ever felt cold in your older home, even with the heat cranked? Ever feel drafts that seem to come from nowhere? And conversely, in the summer, is your home an oven? Many older houses are improperly insulated, if there is any insulation at all. This can have a large impact on your heating and cooling bills. Loose-fill insulation can be blown into your walls and attic to help increase the efficiency of your house, significantly decreasing your heating and cooling expenses.

Cellulose insulation is relatively inexpensive and easy to install. Most of the places that sell loose-fill insulation will lend you a blower for the weekend if you buy a minimum quantity of insulation. You may also need to recruit a few helpers for this project. You will need 1 person to blow the insulation into the walls and at least 1 other person to operate the machine - turning it off and on and filling it with insulation.

The most difficult part of this project is figuring out where to drill access holes into your walls. First you need to determine what will be the easiest surface to repair once the insulation is blown in. If your siding can be easily removed and replaced, you might consider removing a row of siding and blowing in the insulation from the outside of the house. Otherwise, you will need to drill holes inside your house near the ceiling of each level of you house and blow in the insulation from the interior. This tutorial will demonstrate how to blow in insulation from the interior of you house. If you choose to remove a course of siding and blow the insulation in from the exterior, the principles are pretty much the same, but you will obviously patch exterior holes differently than interior holes.

Skill Level & Time To Complete
• Beginner - 4 to 5 days
• Intermediate - 3 to 4 days
• Advanced - 2 to 3 days


When drilling into walls, make sure to avoid wiring and plumbing. Plumbing can be found in bathroom and kitchen walls. Wiring generally runs parallel to the floor about 10 to 20 inches above the floor.

Avoid using blown-in insulation near chimneys and other heat producing objects.

Common Mistakes
When insulating in an attic, make sure to use baffles to keep insulation from blocking airflow along your roof sheeting.

Helpful Tips

Before leaving the store with the insulation blower, make sure you understand how it is used and that you have all of the parts you will need.

Generally insulation requires a vapor barrier to prevent mildew and peeling paint on the interior walls. Blown-in insulation does not provide such a barrier, but is usually not a problem. If you notice paint problems after you insulate, use an interior paint that provides moisture protection.

Leave the blower machine outside of the house and run the hose through a door or window. This will prevent excess dust in your house.

1. This tutorial will focus on installing the insulation from the inside walls of your house. First you need to locate all of the bays in between your wall studs. Use a stud finder to help. These bays are the areas you will be filling with insulation. Do not fill bays that contain chimneys or lighting fixtures. The heat from these items can cause a fire hazard when in contact with insulation.
2. Using a hole saw, drill holes into every bay on each exterior-facing wall of your house. Your hole saw diameter should be a fraction of an inch larger than the nozzle on your insulation blower. Whether you are working from the outside or the inside of your house, you should drill the holes near the ceiling on each floor. Make sure you are just below the top plate of each wall.
3. Once the holes are drilled, you are ready to blow in the insulation. Place the nozzle of the blower into each hole. Wrap a rag around the nozzle, sealing it to the wall. This will prevent insulation from blowing back out through the hole. Hold the rag and nozzle tightly in place. Have your helper start the machine. When the bay is completely filled, the machine will stop blowing insulation and sound like it is struggling. Have the helper turn the machine off. Move on to the next hole.
4. When all the bays are filled with insulation, you need to patch the holes. Whether you drilled from the outside or inside, a good filler to use is an expanding foam sealer. Using your finger, push the loose-fill insulation into the hole, forming a little pocket. Shoot the foam sealer into the hole so that a small mushroom of foam forms on the outside of the hole.
5. When the foam is completely dry, use a long bread knife to cut off the mushroom head flush with the outside surface.
6. If you drilled holes from the outside of the house, replace the exterior siding. If you drilled holes from the inside of the house, use 2 or 3 coats of drywall compound to fill in the pores on the foam patches.
7. Lastly, you will have to paint the wall surfaces as needed, making sure you put on the appropriate primer coat. Repainting the walls will help give you a fresh new start on your newly insulated, heat-efficient home. Sit back and enjoy!



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