Home Garden

How to Measure for Blow-In Insulation

Blown-in insulation can be very convenient to use, especially in attics, crawl spaces and other areas that are difficult to access with traditional rolls of insulation. But before you head off to the home improvement center, you need to know how much insulation you will need. Measuring the space to be insulated before you go shopping can make the job of buying blown-in insulation that much easier.

Things You'll Need

  • Measuring tape
  • Calculator
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Instructions

    • 1

      Measure the length and width of the attic or other space where you want to install the insulation. Multiply the length by the width to get the total square footage.

    • 2

      Find the chart on the bag of blown-in insulation, which shows how many square feet the bag will cover, based on the desired R-value you want to achieve.

    • 3

      Divide the coverage area for each bag by the total number of square feet you have to cover to determine how many bags of insulation you will need to complete the job. For instance, if you have an attic with a space of 500 square feet and each bag covers 250 square feet, you will need two bags to fully insulate the space.

    • 4

      Round up to the next full bag if your calculation shows an uneven number of bags. For instance, if you find that you need 2.3 bags you would need to purchase three bags of blown-in insulation.