Ashburn, VA

How much does attic insulation cost?
$0.65 – $1.40/sqft

The average cost for attic insulation is $0.65–$1.40/sqft. A standard attic insulation job using blown-in insulation for an attic in a 1,200 square foot home is $1,850, but this price does not include the cost to remove any old insulation. The price can vary greatly by region (and even by zip code). Get free estimates from pros near you.

How much does blown-in attic insulation cost?

Author: Daniel W.
Millions of people ask HomeGuide for cost estimates every year. We track the estimates they get from local companies, then we share those prices with you.

Attic insulation will help keep your heating and cooling bills down, whether you need to stop heat coming in from outside or prevent the heat in the house from escaping. When the insulation is inadequate, the life of your HVAC (Heating, ventilation, and air conditioning) system will be shortened, because it will be working for more hours per day than the manufacturer anticipated.

Attic Insulation Cost

An existing home will almost definitely have insulation, but it might be wise to look at how efficient it is. A standard attic insulation job using blown-in insulation for an attic in a 1,200 square foot home is $1,850, but this price does not include the cost to remove any old insulation. Most homeowners spend between $813 and $1492, but this is dependant on the professional you choose.

National Average Cost $1,850
Minimum Cost $800
Maximum Cost $2,800
Average Range $813 to $1,492

This pricing guide covers:

Good attic insulation saves you money

If you have just built a home or have discovered the insulation you currently have is not doing your utility bills any favors, then your insulation project cost will be offset over time by how much you can expect to save on your air conditioning expenses.

In statistics provided by the US Department of Energy, a homeowner can expect to save, on average, 10%–50% on utility bills—depending on how inefficient the old insulation is and what the R-value is of the insulation you are having installed.

What is the R-value?

The R-value is a rating system that tells you how an insulation material performs in resisting the conduction of heat flow—the thermal resistance. The higher the number = the greater the effectiveness of the insulation = the greater the energy savings.

When insulation is being installed in a multi-layered format, the values of each layer get added together to give the final R-value for the space being insulated.

The conditions that affect the R-value of an insulation product include:

  • Type - Some insulation products will deteriorate over time because of age, how heat will affect them, and the accumulation of moisture in the attic.
  • Thickness - The more insulation you have in your attic space, the greater the protection from heat loss or heat gain.
  • Density - Over time, depending on which type of insulation is installed, some products (like loose-fill insulation) will settle and become more dense under their own weight, but this increased density caused by compression does not increase the R-value or effectiveness. Insulation that has been compressed to the point where it reduces or prevents air flow actually has a negative effect on the effectiveness of the insulation’s ability to prevent heat transfer.

Attic Insulation Energy efficiency Audit

Before hiring a company to install insulation in your attic, look up the R-value your home insulation should have on the US Department of Energy’s website. Split into seven regions, the map’s recommendation for your area comes from a combination of factors, including the type of cooling and heating system in your home, the part of the home that is to be insulated, and the local climate.

A loose guide to minimum R values includes the following recommendations:

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

How good is your attic insulation?

To get an accurate answer to this question, you will need to invest in an energy audit. On average, this will cost around $350, and the results from the audit will tell you if there are energy efficiency problems, and exactly where they are in the home.

Some contractors will offer a free energy audit. Texas Energy Experts in Austin, TX, say, “We offer free, professional energy audits, and we'll always be honest about what is best for your home.

When homeowners act on the findings, the resulting savings on utility expenses can be as high as 30%. On the other hand, an audit could save you from the expense of replacing your insulation—if that is not the reason for your HVAC not performing as effectively or efficiently as it should.

What tests are performed in an energy audit?

The types of tests carried out in an energy audit will include:

  1. Utility bill audit – Compares your utility bills for the previous 12 months with those from similar sized homes near where you live.
  2. Infrared camera - Handheld infrared camera equipment reads the temperature in different locations in each room, which will tell where heat is getting in or out.
  3. Blower door test - Determines how airtight your home is by manipulating the air pressure in the home by attaching a huge fan to your front door and blasting it at full power to discover any leaks in your doors, windows, and attic.

Generally, you would need to set aside between 2 to 3 hours for the audit, depending on the size of your home. The audit may also find that you have highly inefficient bulbs, as well as appliances—because of their age.

Many contractors that specialize in ecofriendly products can have great advice on how to upgrade your home to make it more energy efficient, and they’ll know what to recommend for your attic insulation project once they can see the layout.

“Our primary aim as a business is simple – to help you have a sustainable solution for making life more comfortable, more affordable and also doing your bit for the environment.”

Home Upgrade Specialist owner, Nitai Schwartz, in Marina Del Ray, CA

Different types of insulation products

Air will always move from a hotter space toward a colder space, and insulation is the weapon to combat this migration in homes and commercial buildings. Batts and blanket insulation materials are available with facing: a layer of either plastic or paper which is attached to the insulation and allows the product to be stapled to hold it in position.

Batts and blankets

Of all the types of products available for insulation, batts and blankets are the most commonly used because homeowners can use it to insulate their attics without the need for special equipment or any great depth of expertise. It is purchased in rolls of a convenient size and weight, which also makes a DIY (do it yourself) installation easy, other than the somewhat difficult to reach parts of your attic space that make it a challenge to get the product firmly in place.

Attic Insulation

Sizes

  • Batts are typically available in widths of 15” and lengths from 48”–97”. 
  • Blankets are sold in rolls which also come in widths of 15”—to allow them to fit in the space (cavity) between the joists. Like batts, the length of the roll will vary, in this case from 25’–40’.

Materials in batts and blankets

Manufacturers of batts and blankets had used phenol formaldehyde as a bonding agent in the manufacturing process, but this is being phased out because of the potential risk for formaldehyde-related cancer.

Fiberglass

R3–R4 per inch (of thickness), $0.65–$1.20/sqft

If you are installing fiberglass yourself, cover up any exposed skin. The fibers in the rolls of fiberglass will stick to it otherwise. Consider purchasing a few disposable protective coveralls. They cost between $2 to $5, and some come with hoods to cover your head.

A good plan would be to have enough coveralls on hand so you can have a new set each time you return to the job. Also buy masks to avoid breathing in the fiberglass shards—get a pack of 4 x 3M masks for under $6 from your local hardware store.

Rockwool

Between R4–R5/inch, $0.75–$0.85/sqft

Rockwool, as the name might suggest, is made from stone. Chalk and basal rock are melted into a lava in a blast furnace, and then blown into a large spinning chamber that spins the lava into fibers, not unlike cotton candy. Its temperature maintenance properties are derived from the capability of the stone lava fibers to trap tiny pockets of air within the product’s structure. The air that gets trapped creates a barrier which works with the fibers to keep hot air out and cold air in.

In addition to its insulation properties—which are slightly higher than fiberglass—it is also able to withstand temperatures over 1,000 degrees and provides a layer of soundproofing from outside noise. Being made from rock, it is a very sustainable product, often using leftover or waste materials as the ingredients.

In its installation, it does not require staples to hold it in place since it will generally spring into shape filling the spaces you need it in. In contrast to fiberglass insulation, it does not cause skin irritation or require the installer to wear protective gear.

Despite the fact that it contains a known carcinogen called crystalline silica, there is no evidence from any scientific study showing a connection with lung disease from inhaling the fibers. Depending on where you live, rockwool can be harder to locate than other insulation options.

Cotton batts

Between R3.5–R4/inch, $0.76–$1.41/sqft

Cotton batts, also known as “blue jeans,” doesn’t cause any health concerns, is formaldehyde free, and is another ecofriendly insulation material option—it’s processed with as much as 85% recycled fibers and doesn’t require the use of power-hungry machinery to produce the end product. It is also treated with borate fire retardant, which in addition to making it safer, acts as a repellent to certain insects.

Cotton batts has a low density, and as a result does a good job of not allowing much transfer of heat from the air above the insulation to the air below—thermal conductivity. Unfortunately, it is not easily available everywhere.

Loose-fill Insulation

When the insulation is being added to, or replacing, the insulation in an existing home, loose-fill will have an advantage over batts or blankets. Loose-fill insulation is usually made of fiberglass or cellulose.

Fiberglass

R 2.2–2.7/inch

Normally it only contains around 30% recycled glass. At approx. $1/sqft, it is a popular option for many homeowners who are insulating their attic space. It can be used as the only insulation product or blown in over existing cellulose loose-fill.

It won’t settle or become compressed over time and fiberglass cannot be damaged by water, so it will not need a moisture barrier when used next to a wall or over an air-conditioned space. As with installing fiberglass batts and blankets, wear protective gear if installing it yourself.

Once blown into your attic space, the product could have a fluffy structure because of a lack of density, which will result in a drop in its overall effectiveness. This could be remedied by the top surface being topped with a denser loose-fill application, or insulation blanket products.

Cellulose

R 3.2–R 3.8/inch, $1.20–$1.25/sqft.

Cellulose loose-fill insulation is among the oldest forms of materials used in building insulation applications. In the past, many ingredients were used to create this insulation material, including newspapers, cardboard boxes, phone books, cotton, straw, corncob, and sawdust. Since the 1950s, the main ingredient has typically just been newspaper—grind it up, remove the dust, and add flame retardants, including boric acid.

Despite being made from something that burns very easily, compared to fiberglass, cellulose insulation is much denser, so it greatly limits the flow of oxygen to a fire. In most cases, 80% or more of the materials used for cellulose insulation are recycled.

In spite of the R values of each product, it has been said that compared to fiberglass, loose-fill cellulose can perform 20% to 30% better at reducing energy expenses.

Blown-in

Blowing in loose-fill insulation is easier than laying rolls—it blows into tight spaces where the slope of the roof meets the perimeter walls, and also gets around any plumbing pipes or electrical work. Installation is a little more difficult than directing the hose and monitoring the height or thickness of the layer as it is distributed in the attic space.

Blown-in insulation is sold in tightly filled bags which are opened onsite and fed into a blower. This pipes in the loose material through a large hose, allowing the installer to direct the flow wherever it is needed. When blowing in, the process can generate an irritating degree of airborne dust, which requires the installer to use a breathing mask while doing the work.

Check with the contractor to see what action plan they are putting in place to protect your home from the dust the work will produce.

Spray Foam Insulation

Attic spray foam insulation is one of the most expensive options available. When installing, two synthetic materials are combined onsite using special equipment mounted to a truck or trailer to create spray foam insulation. A chemical reaction occurs which causes the ingredients to expand their liquid volume by as much as 60 %.

Attic Insulation Blown-in Spray Foam

The resulting foam creates a powerful thermal insulator in a thick layer. When applied professionally, using heated hoses connected to a mixing gun, this insulator fills up all the cracks and gaps in the attic space. Once the foam is dry, it will become solid, and at this point the attic spray foam insulation is fully water resistant.

The foam can release particles or allergens into the air. While small aerosol cans of foam can be purchased from your local hardware store to do touch-up work where needed, this is very much a job best left to the professionals.

If the foam is sprayed before the chemicals are at the right temperature, or if the chemicals are combined in the wrong proportions, the resulting foam will not expand as it is designed to do. In some cases the foam will even retreat after expanding, thereby reducing its true R-value and overall effectiveness. Foam can be sprayed into both horizontal and vertical attic spaces.

Types of spray foam insulation

The two types of attic foam insulation are open- and closed-cell polyurethane. It is fair to say that the larger the attic space, the lower the cost per foot.

Open-cell polyurethane

R 3.5–R 3.7/inch, $0.45–$0.65/board foot (1 square foot measuring 1 inch thick)

Open-cell polyurethane insulation stops the movement of air in your attic space, but it requires a moisture barrier in some installations because it can allow moisture to pass through.

Also known by the name “half pound foam,” it does come with health concerns: during the process of spraying this foam into your attic space, various volatile organic compounds (VOCs) and chemicals are released into the air.

Since these elements are connected to various serious health issues, including asthma, the installer will be required to use an appropriate breathing filtration gear and equipment.

Homeowners should wait up to three days before going back into the home to be sure they won’t be breathing any remaining airborne particles.

Closed-cell polyurethane

R 6.0–R 6.5/inch, $1–$1.50/board foot

For both commercial and residential insulation applications, closed-cell polyurethane is the most efficient material for insulation available, but it also releases VOCs during installation. Often referred to by the name “two-pound foam,” its high R-value has a price tag to match when compared to open cell foam, and the blowing agents used are considered to have a high potential to affect global warming negatively.

With a density of two pounds per cubic foot in an attic space, closed cell foam will create a barrier that is very resistant to water, has a low Perm (moisture vapor permeability) rating, and is very effective against the movement of air.

This density has been found to provide the best insulation for the widest range of building temperature control purposes.

When used in walls, the strength and rigid nature of closed-cell polyurethane foam is also known to double or triple the walls’ ability to resist wind loads—known as racking strength.

Alternative attic insulation options

Radiant barriers

A common sight in residential attics in hotter climates is the addition of radiant barriers, which are to reduce heat gain during the summer months and thereby drive down utility costs related to cooling expenses.

Radiant barriers block heat transfer by reflecting heat energy instead of absorbing it like traditional insulation products. The common measurement used to rate insulation performance, the R-value, does not apply to radiant barriers. These barriers are made using a very reflective material like aluminum foil.

Instead of absorbing heat, a radiant barrier works by reflecting direct sunlight out of your roof rather than absorbing it into the attic space by conduction. When the radiant energy hits the radiant barrier at a perpendicular angle, the barrier will reflect the heat away best. The barrier is applied right next to the roofing materials and any exterior-facing wall surfaces in your attic space.

Many homeowners will elect to install a radiant barrier as a second layer of protection having already installed batts, blankets, loose-fill, or spray foam in the attic floor.

How much do radiant barriers cost?

  • $0.50 per square foot installed
  • $0.10–$0.25/sqft for single-sided barrier or $0.15–$0.50 for double-sided barrier—if you are buying rolls to install yourself 
  • To install a single-sided barrier in a 1,500 sqft attic yourself, your materials cost could be as low as $150 to $375, or for a double-sided barrier between $225 and as much as $750.

Additional costs

If you are replacing the attic insulation in an existing home, then you will have to pay for its removal.

Expect to pay professionals $1 per square foot for insulation removal, but this cost could be lower if you are adding that service to the quote for the new insulation.

As with installing it, removing old blow-in insulation could produce dust that requires you to stay out of the home for three days. Check with the company to see what they will be doing to prevent this.

Tax Credits and Rebates

Many federal tax credits for energy efficiency focus on upgrades and enhancements. Energy Star states that “Adding adequate insulation is one of the most cost-effective home improvements that you can do.”

As of October 2018, the tax credit amount is 10% of the cost, up to $500 (not including installation) of typical bulk insulation products such as batts, rolls, blow-in fibers, rigid boards, expanding spray, and pour-in-place.

Products that air seal (reduce air leaks) can also qualify, as long as they come with a manufacturer's certification statement, including:

  • Weather stripping
  • Spray foam in a can, designed to air seal
  • Caulk designed to air seal
  • House wrap

You can see more information here, including links to the following:

  1. How to apply
  2. Insulation efficiency through home performance with ENERGY STAR
  3. Heat & cool efficiently at home

In addition, there is a wealth of other information on more energy efficiency considerations, and enhancements, including appliances and other home upgrades.

Outside of the federal programs, because of a large focus on sustainability and reducing energy consumption for the population at large, it is often possible to get other rebates from manufacturers.

Check with your local governing authorities, as well as your utility provider, to see if there are any rebates available to reduce or reimburse the entire cost of having an energy audit performed on your home.

In addition, you may also find rebates for more efficient appliances, which you could take advantage of if issues with your appliances were exposed in the findings of your energy audit.

Hiring an attic insulation contractor

Before you narrow down your short list of contractors to install your attic insulation:

  • Ask the contractors for a copy of their certificate of insurance so workers are covered under the contractor's insurance policy rather than yours if they have an accident on your property.
  • If you’re not sure which type of insulation or material to use, ask your final three contractors for recommendations. Hage Energy in Houston, TX, say “Hage Energy can come to your home for an inspection of your attic and current insulation situation. If we feel we can improve your insulation, we will offer blown-in attic insulation to be placed in very specific parts of your attic.”
  • Hire a contractor with years of experience installing all types of attic insulation.
  • Choose a contractor who gives a warranty on parts and labor

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