Attic with insulation

Be sure your attic is air-sealed before adding insulation. (iStockPhoto)

In the battle against winter cold and sky-high home energy costs, the first line of defense is attic insulation. According to the Environmental Protection Agency’s estimates, homeowners can save an average of 15 percent on heating and cooling costs by sealing up air leaks and adding insulation to their attics – and that’s just the average.

If you live in the northern part of the United States, your savings may be even greater because the climate is more severe and energy for heating can be more expensive.

The really good news is that adding insulation is an improvement that qualifies for tax credits and is excellent at returning value on your investment.

Current federal tax credits will cover 10 percent of the cost up to $500 for qualifying insulation and air-sealing products purchased in 2016, so it makes sense to jump on this before the end of the year in case these incentives are discontinued.

Note: These credits do not cover installation costs. For more about this particular program, see You can check whether additional programs are available in your state through, an online resource for energy efficiency initiatives.

When it comes to value, Remodeling Magazine’s 2016 Cost vs. Value study determined that the addition of fiberglass insulation to an attic offers a better return on investment than any of the other 30 projects studied in this year’s report.

Remodeling Magazine’s cost source for the report, RemodelMAX, estimated the average nationwide cost of insulating an attic to be $1,268. Real estate professionals who responded to the survey projected that, within a year of insulating, this improvement would increase the average home’s sales price by $1,482, resulting in a 116.9 percent return on the investment.

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An Insulation Primer

Basic home building materials used for siding and roofing are great at providing shelter but readily allow the conduction of heat. The result is heat loss in the winter or heat gain in the summer.

Insulation materials, typically made of fiberglass, cellulose or foam, have an open-cell structure that resists heat transfer – so when these materials are added to attics, walls and floors, they reduce energy loss. Just how effectively they do their job depends on the particular material and quality of installation.

An insulation material’s ability to resist heat transfer through conduction is measured and rated by an R-value: the higher the R-value, the better the insulation.

The R-values to target in your home depend primarily upon your climate and secondarily upon the part of the house being insulated. It’s most important to insulate the attic because that’s where the majority of a home’s heat is lost.

Fiberglass blanket insulation provides an R-value of from 2.9 to 3.8 per inch of thickness. Loose-fill cellulose insulation can vary from about 3.2 to 3.8, depending on how thoroughly it is installed. Sprayed polyurethane foam can be rated as high as 6.0 to 7.3 per inch. Air pockets, shallow coverage or compressed insulation diminish effectiveness.

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How Much Insulation is Right? offers complete information on figuring the right amounts of insulation for your home. Note that the lowest recommended amount is R-30, which is the equivalent of about 10 inches of fiberglass or 8 inches of cellulose. For very cold climates, R-60 is recommended.

If your attic already has some insulation, you’ll need to measure its thickness to determine the amount you should add. When in the attic, be sure to stand or kneel only on fully supported planks or joists – if you step between the joists, you’re likely to fall through the ceiling below.

Before insulating an attic, it should be air-sealed, especially in cold climates, where warm air that rises into the attic can cause heat loss and create moisture problems.

Air sealing is the practice of using expanding foam to seal up cracks, crevices and connections where walls, plumbing stacks, electrical wires and chimneys penetrate the attic. This keeps the rooms below from leaking expensively heated air into the attic. Though some do-it-yourselfers can tackle this, it’s generally best to have it done by a professional.

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Basic Insulating Practices

If you’re adding more to existing insulation, it isn’t necessary to use the same material. It’s okay to blow loose-fill insulation on top of fiberglass batts or to place fiberglass batts over loose-fill.

If you intend to install batt or blanket fiberglass insulation, note that you can buy it with or without an attached foil or paper facing, which serves as the vapor barrier.

When you’re insulating a previously uninsulated attic, buy the type with a facing and position that facing toward the warm-in-winter side (against the ceiling below). When you’re adding more to existing insulation, however, buy unfaced insulation or use loose-fill insulation, which doesn’t have a vapor barrier.

In an unfinished attic, insulation is installed between the ceiling joists of the room beneath the attic (the attic’s “floor” joists). When adding more batt or blanket insulation to an attic with existing insulation, the conventional wisdom is to orient the new batts perpendicular to the joists.

Be aware, however, that doing this will make it much harder to identify where you can safely stand or kneel, because you won’t be able to see the joists once they are covered. So start at the outer perimeter and work your way toward the attic hatch.

Place and fasten planks or plywood, supported by joists at both ends, where needed for safely accessing and working in the attic.

Do not install insulation over the eaves vents – this will interrupt proper attic ventilation. Also, to avoid causing a fire hazard, never place insulation over recessed light fixtures unless the fixtures have an “insulated ceiling” rating. Use wire mesh to hold back insulation if necessary. Last but not least, insulate and seal the attic access panel.

Don Vandervort is the founder of

Tags: real estate, housing, home improvements, energy efficiency, energy

Don Vandervort is the founder of, a leading home improvement advice site. Don has authored many home improvement books, written extensively for, and served as a segment host on HGTV.