How Much Does it Cost to Insulate a House?

Types of Insulation

Insulation is broken into four categories. The choice of insulation you make largely depends on the area you need to insulate, your home’s climate location, the current R-value of your home, and your budget.

Spray Foam Insulation

Spray foam insulation seals leaks and gaps inside existing walls and is the perfect solution for those who are looking for a relatively inexpensive way to fix a larger problem, while increasing their home's R-value.

• How it works: Liquid polyurethane is sprayed into the cavity of the wall, where it then hardens and transforms into a solid foam.
• Types of foam: Spray foam comes in two varieties: half-pound open-cell foam and a more dense type called two-pound closed-cell foam. Of the two, the two-pound variety does a better job at insulating, but isn't always the right choice for the job or the budget.
• Benefits of spray foam: Of all the foam insulators, closed-cell foam has the highest R-value of any insulator you can buy, up to R6 per inch. Furthermore, spray foam takes up much less space than fiberglass or comparable blown-ins. It should also be noted that, when done properly, spray foam can save you as much as $500 a year in energy costs.
• Cost: Professional application of spray polyurethane is typically calculated by the board foot, which is measured like this: 12" wide x 12" long x 1" thick.

To calculate the board footage of the space you want to spray, multiply the area you want to insulate by the depth in inches. The formulas looks like this: sq. ft. x depth in inches = board feet. To calculate the price of your job, take the cost of the type of spray foam you choose:

• Open-cell spray foam is generally 35 to 55 cents per board foot
• Closed-cell spray foam is generally $1.00 - $2.00 per board foot

Then apply it to your measurements. For example, 2,000 bd. ft. of space at 0.50 = $1,000.

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Blown-In Insulation

Blown-in insulation has been used for many decades in homes all over the United States. It is usually made from a paper-like material known as white cellulose, which is usually processed from reclaimed and recycled newspapers, cardboard and so on. It works very well and has a higher than average R-value, depending on the depth blown.

• How it works: A mechanical blower is attached to a corresponding box full of cellulose. The user points where they want their insulation to go and fills the space.
• Types of blown-in insulation: Though there are several types of blown-in insulation available, the most common is a borate-treated Class I type called loose fill, consisting of pelleted cellulose.
• Benefits of blown-in insulation: When packed densely into place, fire-proof cellulose loose fill insulates very well. It is also easily blown into tight places, further increasing the R-value (10" = an R-value of 36). It is also moisture resistant, and the borate keeps insects and other vermin at bay.
• Cost: Blown-in insulation is perfect for the weekend warrior looking to get the job done cheaply. There is little learning curve involved with the application, and a DIY job will cost you about $500. Calling in the pros, on the other hand, will run you about $1,500 to $2,000 for an average 1500 square foot home. So saving $1,000 might be worth the effort.

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Fiberglass Batts

Fiberglass batts are among the most inexpensive ways to insulate your home, especially when the walls are already open, like in an attic area. The important part about installing fiberglass batts is to pay close attention to how they are installed. One loose corner or tear reduces any hard-earned R-value (which is displayed on each roll) you accrued from the installation.

• How it works: Large, rolled batts of fiberglass are designed to fit the standard distance between studs. They fill the large void and stop air from penetrating the exterior wall.
• Types of fiberglass batts: Fiberglass batts usually come in a single variety. The only real variance between one roll to another is overall thickness and color. Choose what works best based on what area of your home you are insulating and recommended R-value.
• Benefits of fiberglass batts: Fiberglass batts are ideal for those who need to insulate quickly and save money in the process. It is simply installed by anyone with a putty knife, a utility knife and a tape measure. When installed tightly and securely, fiberglass batts improve energy efficiency by 25 to 30 percent.
• Cost: The average cost per square foot is between $0.64 - $1.19. So, for a 500 square foot area, your estimate will vary between $145 to $200, if you do it yourself. For a professional job, add between $150 to $300 for labor, and you're looking at around $300 to $500 for 6 hours of work.

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Reflective or Radiant Barrier

Usually installed in attics to reduce sweltering summer heat and insulate against winter cold, radiant barriers are perfect for reducing heating and cooling bills, while increasing your home's R-value. Reflective barriers, though different in design, exact a similar principle in function.

• How it works: Reflective or radiant barriers differ from other insulation types due to their thermodynamics. While most insulation works by slowing heat flow, the basic principle of radiant and reflective barriers is that they reduce radiant heat gain instead of slowing it. For example, as the sun bears down on your roof, the heat transfers through the material radiating into your attic and warming it. While normal insulation slows this heat transfer process, reflective or radiant barriers reflect and absorb to keep the area tepid.
• Types of reflective or radiant barriers: The substrate of a reflective barrier usually consists of plastic films, cardboard, strand board and air infiltration board, which is then covered by a highly-reflective aluminum-type material. These basic barriers can be combined with other insulation to optimize their effects.
• Benefits of reflective or radiant barriers: Though this type of insulation works better in warmer climates than in cool, the average savings per home is around 10% (or $150) in terms of cooling costs. Add to that nominally more when combined with other conventional insulation types.
• Cost: Depending on the type and brand you choose, and whether you select rolls or boxed, the average square foot of radiant barrier costs about 15 to 30 cents. So to cover a typical 500 square foot attic, you'll likely spend $175 to $325, with double-sided barriers being slightly more expensive. To pay for a professional installation, add to that between $500 to $750.

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Home Insulation Costs - What You Need to Know

The average American home, according to statistics, measures around 2500 square feet and tends to be a two-story structure. For anyone researching estimates associated with insulating their home, it's important to make the distinction between the separate costs associated with each part of the home. That's because the costs vary depending on what you're insulating – walls, roofs, garages, etc.

Insulating Walls

Since most homeowners are seeking to insulate previously built structures with drywall, blown-in insulation works best in the interior. A simple hole is cut, insulation is blown in, and the hole is sealed, leaving the room warmer and more efficient, at about $1.00 per square foot. You can also insulate when finishing a wall's rooms as well -- particularly with basements and garages. This is when batt insulation is particularly useful.

Roof Insulation

Roofs need to be sealed prior to insulation, which means seeking out and filling gaps, closing soffit vents, and so on. Water, after time, degrades insulation, rendering it useless. An insulated and sealed roof leads to a warmer attic in winter, and a cooler attic in summer. Look to spend about $1,500 to pay for a professional job, or a bit more for radiant or reflective barriers.

Insulating Garage Doors

If you have an attached garage or simply want to make your garage warmer, insulating the door with foam kits is simple and only takes a few hours to complete. Depending on if you opt for batts, foam boards, or reflective insulation, you'll pay about $200 for a 9' door.

Crawl Space Insulation

A crawl space is insulated differently depending on if it is ventilated or not. It should also be noted that in order for the insulation to be effective, moisture needs to be removed. If your crawlspace is well-ventilated, insulating it with batting is ideal and often works best. Cost estimates vary greatly depending on the size of your crawl space, from a $3 for one roll to a $300 for larger spaces.

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Insulating an Attic: Costs and Considerations

Keeping an attic warm in the winter is costly. But when the alternative is to turn off the heat or simply wear warmer clothes, insulation is the wiser choice. Though not always considered a DIY job because of the dusty and cramped environment, insulating your attic brings hefty benefits in terms of savings and increasing your home's R-value. For those who would rather pay for a professional insulation job, the good news is that there are many qualified contractors available who do good work for a relatively low price. Estimates vary depending on the insulation type you choose and the area in which you live. For the most part, however, you'll be looking at paying about $1,300 to $2,000 total for the entire job.

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What Does R-Value Mean?

R-value is a calculative method referring to thermal resistance. It is also a thermal measurement unit for particular materials in relation to how they insulate. Theoretically, a higher R-value means more heat resistance, which also means greater insulative qualities. All insulation products have an R-value associated with them, and display it prominently on their packaging. The R-value is a somewhat complicated calculation, but all you need to know is what R-value you need, based on where you live and what type of space you are insulating, and choose a type of insulation accordingly. In general, those who live in colder climates need products with a higher R-value, while those in warmer climates need less R-value. To get a better idea of what your R-value should be, the Department of Energy recommends the following R-values for unfinished attics:

• Hot climates: R-30
• Temperate climates: R-38
• Cold climates: R-49

Rebates and Savings

Weatherizing your home comes with some government tax credits and rebates, though many federally-mandated versions expired several years ago. However, some states still offer weatherization rebates and discounts and other incentives for insulating your home. For more details on whether your state offers these types of perks, a directory can be found here.

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