Don’t DIY Home Insulation If You Don’t Know How

For many homeowners, proper attic insulation is a common concern and an easy target for improving energy efficiency. Most older homes, and even many newer ones, simply lack the proper amount of insulation in their attics. However, there are many things to consider when deciding to add or upgrade the insulation. It may seem like a fairly easy Do It Yourself (DIY) project for the more handy homeowner. But failing to make the necessary preparations or proper installation can result in diminished results and return on the investment.

Cellulose Insulation Blow In Attic Installation CIMA

Cellulose Blown In Installation

Fiberglass Batt Attic Instalation Coutesy DOE

Fiberglass Batt Installation

Here are some sound recommendations for homeowners considering an insulation project:

1. Don’t DIY Home Insulation If You Don’t Truly Know How
Consider hiring a qualified professional insulation contractor for the project. While it is possible for homeowners to install attic insulation themselves, the fact is it’s harder than it looks. Getting the maximum energy efficiency requires perfection when it comes to insulation. The added cost to get the job done right is typically offset by the increased efficiency and savings realized by homeowners. For those considering cellulose insulation, the Cellulose Insulation Manufacturers Association members offer a referral service for qualified installers.

2. Prepare The Attic Before Installing Insulation
If the attic is not properly prepared and sealed, the insulation will not achieve the maximum energy efficiency. This is true whether the insulation product is batts or loose fill blown in. Cellulose Insulation blown into the attic will provide the best sealing overall. With fiberglass batts, it’s even more critical to prep and seal. Batts are seemingly easier for DIY installation, but they just do not effectively seal the space. In either case, whether DIY or Pro Installation, following some basic preparation steps will make a big difference in obtaining the best results. Learn more here.

3. Select The Best Insulation Product
The two most common DIY products for attic insulation are fiberglass batts and blown in cellulose insulation. There are very distinct differences in these products to consider:

  • First, if environmental factors are a concern, cellulose insulation is one of the most Eco-Friendly building products available. In addition to providing excellent insulation characteristics, cellulose is also made with up to 85% recycled material, has exceptionally low embodied energy and is produced regionally, all resulting in fewer environmental impacts.
  • Where older insulation in the attic is being covered, cellulose insulation is the perfect choice as it can easily be blown in over existing insulation.
  • Fiberglass batt insulation is easier to install than blown in cellulose insulation for most homeowners. However, DIY installs with batts typically fail to effectively seal the attic space.
  • Cellulose is a bit harder to install as it takes the proper blower and hose equipment (available at most retailers where the product is sold) and requires at least two people. However, if the product is blown in to the level recommended on the packaging, it will typically provide better coverage and sealing than batts.

In either case, the DIY homeowner should follow the manufacturer’s installation recommendations exactly and consider researching online for installation demonstrations. These are readily available for both products.

4. Installation Health Factors
Fiberglass batts cause skin irritation. The glass fibers penetrate the skin and can cause itching, burning and in some cases a reaction or rash. Full protective clothing, face mask and safety goggles are recommended. Cellulose does not cause skin irritation like fiberglass and only requires a basic dust mask.

Homeowners that do decide to go the DIY route need to determine the proper R-Value for their home. The U.S. Department of Energy provides a regional map for recommended R-Values. If adding over existing attic insulation, it is important to determine the current R-Value. This is pretty straight forward with existing cellulose insulation. Check this insulation calculator to get an idea of the potential savings from upgrading attic insulation.

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  1. John Penfield says:

    Do I need a vapor barrier with Cellulose? I live in St. Paul, MN.
    I want to put in my knee walls where the roof meets the 2nd story floor.
    THX,
    John

    • CIMA Admin says:

      This question requires a somewhat of technical reply. We need to first understand the terminology. Vapor retarders are now divided into three classes. Only Class I vapor retarders with a perm rating of 0.1 or less are “vapor barriers.” Class II are 1 perm or less but greater than 0.1. Class III are 10 perm or less but greater than 1 perm. Building scientists are now in agreement that vapor barriers should be avoided in all but the most extreme cases, such as arctic or near arctic climates or outside walls of structures where it is known very high relative humidity will be constant such as pool enclosures or conservatories. The general rule, as articulated by Joe Lstiburek (and we believe endorsed by every other building scientist,) is that you don’t use a vapor barrier when a Class II or Class III vapor retarder will provide satisfactory performance. And you don’t use a vapor retarder at all when you don’t need one. With that said, Class II or Class III vapor retarders are recommended in most of the contiguous US. Polyethylene is an example of a vapor retarder, and most building scientists say 9000 Heat Degree Days (HDD) is the point where poly might begin to make some sense. As to your situation, the Twin Cities are less than 8000 HDD. Some coated kraft papers, including batt insulation facings, are Class II vapor retarders, and both cellulose and unfaced fiber glass insulations are Class III vapor retarders. Plain latex paint is usually identified as a Class III vapor retarder, and with multiple coats may be a Class II vapor retarder. Cellulose is actually a “smart” vapor retarder, since its permeability decreases as moisture content increases. So the short answer, you really do not need a vapor barrier with cellulose insulation. But be sure to check your local building codes as some municipalities still require vapor barrier regardless of the insulation type.

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