Installing Vapor Barrier Blown Insulation to Your Basement

  • 2-4 hours
  • Beginner
  • 250-1,000
What You'll Need
Vapor barrier blown insulation
Cardboard baffles
Staple gun
Insulation blowing machine

Consider blown insulation for your basement. When coupled with a vapor barrier, it will provide a sealed, dry environment. Blown insulation is forced into wall cavities with a blower. It is preferable to other types of insulation because it fills every void in your basement’s wallboards. Although blown insulation is ideal for use in basement walls, it isn't perfect for attic spaces because if it becomes crushed it will lose its R-value and not be as good an insulator.

Choosing the Type of Insulation

Blown insulation is very popular because it can easily and quickly be installed to any wall cavity without much work. There are a few different types of blown insulation that are popular.

The most popular types of blown-in insulation include fiberglass and cellulose. Fiberglass insulation is manufactured from silica. The silica is melted and spun into a very fine fiber that looks like wool. Cellulose insulation is mostly made from recycled paper and either ammonium sulfate or boric acid, which makes the material fireproof. These fibers are then blown into the wall cavities to provide insulation.

A vapor barrier can be blown in at the same time. They are also made from several different materials. They are thin plastic sheets or other materials which prevent water from penetrating the barrier. There are also some barriers that can be painted onto the surface. They are ideal for installing over finished walls.

Calculating Amount of Insulation

Before buying the insulation, you need to determine how much insulation is required to fill the voids in your walls. Take advantage of the many insulation calculators available on the manufacturer's websites. Allow 20% more filling than you need because blown-in insulation can settle over time, which creates inefficient results.


Cut a hole in the cavity wall to allow access and fit cardboard baffles all the way around the hole to prevent the filling from protruding. A loose-fill insulation machine will be required to complete the project. They run on electricity and are available for rent. Read the manual to understand exactly how to use the loose-fill insulation machine so that you don't waste any time or money.

Filling the Hole

Fill the cavity using the loose-blown insulation by loading the machine with the loose-fill insulation, then switching the machine on. Every insulation machine works slightly differently, so read your user manual to find out how to use it. Most will have trigger controls, which make it easy to control the flow of blown insulation.