How To Install Batt Insulation

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With the ever increasing prices of home heating and cooling, as well as the continued effort for energy conservation, insulation is one of the best ways to ensure your home saves money and electricity. Installing insulation will help limit the flow of heat, thus keeping heat from entering your home in the summer, and hot air from escaping your home in the winter, allowing you to use both your air conditioner and heater less. (For more information on affordable home heating options, see Alternative Ways To Heat Your Home.)

What You'll Need:

  • Gloves
  • Dust mask
  • Utility knife
  • Straightedge
  • Safety glasses
  • Blanket insulation
  • Vapor retarder

Terms To Know:

Batt: A batt is a precut panel of insulation, also known as blanket insulation. Though available in many sizes, they are measured according to the most common stud cavity sizes.

Roll: A roll of insulation is a continuous sheet that can be cut to fit any sized stud cavity, and is also considered a part of blanket insulation.

Stud Cavity: The space between studs inside your wall. This is where your insulation will be installed.

R-Value: The level of heat resistance offered by a particular style of insulation. The larger the R-value, the more heat resistance the insulation will offer. The R-value is determined by the insulation's material, thickness and density. Varying sized insulations with equal R-values will resist heat to the same degree.

Ready for Planting Finished Product

Vapor Retarder: A barrier placed over insulation to prevent negative effects of condensation. The retarder guards against mold and other moisture damage, and typically comes in thin sheets of plastic or foil. Insulation with facing already attached usually does not need a vapor retarder.

Facings: Paper, vinyl or foil sheets attached to one side of insulation. The facing provides an easier surface for the insulation to be fastened to a wall, holds the insulation material together, and often acts as a vapor retarder.


1. Blanket insulation can be purchased in two forms. Batts are precut strips of insulation, sized to fit the most common widths of stud cavities in your walls. Rolls of blanket installation must be cut to fit. Measure the size of your stud cavities, the space in your walls in between each stud, and purchase batts or rolls accordingly.

2. To trim down a batt, set the piece of insulation onto the floor, directly in front of the stud cavity it will be placed in. Measure the width of the batt against the width of the cavity, and mark where you must cut. Lay a two-by-four inch board down on top of the insulation, creating a straight line to cut along. Cut the batt with a utility knife along the line of the board.

3. Set the cut piece of insulation into the stud cavity, starting at the top. Firmly press the insulation into the space, until you have tucked it in all the way to the bottom. Though it should fit snugly between the studs, the insulation should not be tightly compressed. This can reduce the insulation's heat resistant properties, known as R-value. Trim any excess insulation that cannot fit in the bottom of the cavity.

4. There may be wire, pipes or electrical boxes along your walls, inside the stud cavities. Cut out the insulation around boxes, creating as snug a fit as possible. For electrical wires, try slicing the insulation batt in half, placing the back half behind the wires, and the front half over them. For larger pipes, while it may be a tight squeeze, fitting the insulation beneath them will help prevent freezing in the winter.

5. If you purchased insulation without facing, you will most likely want to install a vapor retarder to protect the insulation from condensation. You can purchase a vapor retarder in the form of thin plastic sheets at most hardware and home improvement stores. Secure the sheet of plastic to the top and bottom of a stud every one to two feet, as well as studs where two sheets of plastic overlap.

6. Once you have completed the vapor retarder installation, your insulation is ready for use.

Installing your home's insulation is a great way to cut energy costs, and stop wasting precious hot and cold air generated by your heating and cooling systems. The key to effective insulation is proper installation, so be sure each piece is fit to the size of the stud cavity as perfectly as possible. Gaps will allow for air to pass by the insulation, while too tight of a fit will actually reduce the R-value. Take your time to measure and cut each piece, ensuring a quality installation.

Last Updated: July 23, 2012
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About Alexandra Kerr Through Ideal Home Garden, Alexandra covers topics ranging from interior design to home improvement, gardening and cuisine. Having a passion for cooking and entertaining in her own life, she hopes to communicate her love of home design and decorating with her readers. 

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