Blown In Insulation Cost and Ultimate Guide

Blown In Insulation

The average cost of blown in insulation is $1.10 to $2.75 per square foot of coverage based on the thickness or depth of the insulation. Obviously, cost in the attic where depth can be as much as 15 inches will be higher than the price of blown in wall insulation that is three to five inches thick.

Blown In Insulation Cost

This chart gives you an overview of the cost for insulating various areas with blown in insulation, which is also called blow-in insulation, blown-in insulation and loose fill insulation.

Location

Amount

Cost Range

Per Square Foot

Entire New House

Varies

$2,600 - $7,400

$1.10 - $2.75

Attic Floor

8-18 Inches

$1,500 - $5,500

$1.60 - $2.75

Exterior Walls

3-5 inches

$1,825 - $3,360

$1.10 - $1.80

2-car Garage

Varies

$1,375 - $3,100

$1.10 - $2.50

Garage Walls

3-5 inches

$650 - $900

$1.10 - $1.80

Garage Attic Floor

Up to 15 inches

$580 - $1,850

$1.40 - $2.50

Did you know? Not all blown in types can be used in the wall – in fact, just wetted cellulose insulation is appropriate for use in wall cavities and other vertical applications.

Blown In Insulation vs Spray Foam Insulation

Blown In Insulation vs Spray Foam Insulation

Blown in insulation is much more affordable than spray foam insulation, but it has two disadvantages. First, it doesn’t seal the space, meaning air will still flow in and out of the area if there are gaps in the home’s sheathing or around windows and doors.

Secondly, it isn’t as versatile. While you can apply spray foam insulation almost anywhere, loose fill generally has to be supported – as in walls where it is covered with drywall, or be installed on the floor of the attic. You certainly wouldn’t want to leave blown cellulose exposed, as you can with closed cell foam insulation.

See our Spray Foam Insulation Buying Guide and price review for full details on that pricey insulation with outstanding R-value and weather-sealing performance. Foam is a great choice for sealed attics, rim joists, basement and crawlspace walls and hard-to-reach spots where closing air gaps is essential to a well-insulated and energy efficient home.

What’s Here

This blown in insulation guide covers all important topics: Blown in insulation cost per square foot, average cost for attic use, wall applications (cellulose insulation) and much more. Everything you want to know about fiberglass, rock wool and cellulose blown in insulation is covered here.

What is Blown In Insulation?

The name refers to several types of insulation that are installed using a machine to blow or distribute the insulation into attic space – most common - but or other locations such as wall cavities when wet cellulose insulation is used.

Bags of loose insulation are loaded into the machine, which blows the insulation into place. The process breaks up the clumps of insulation found in the bags – insulation that is tightly compacted into clumps reduces its insulation performance, its R-value. This is because most insulation types make use of air pockets that hold heat and create a barrier to heat transfer.

Did you know? The materials are not glued to a backing, for example, like faced fiberglass bats or rolls. That’s why it is also called loose fill insulation.

Blown In Insulation Cost and Options 

Material

R-value / Inch

Installed Cost / Sq. Ft.

Blown in Fiberglass

2.5 - 3.5

$1.10 - $2.00

Blown in Rockwool

3.0 - 3.7

$1.50 - $2.25

Blown in Cellulose

3.2 - 3.7

$1.60 - $2.30

Blown in insulation aka loose fill insulation and blow-in insulation is the fastest growing niche in the insulation market. Some quibble that there is a difference between blown in insulation because a machine is involved while loose fill can be sprinkled around. That’s not a distinction made in the insulation industry. While in theory, either method can be used, installing it with a machine makes the most sense.

Why? Because it is so easy to install and makes a good DIY project for homeowners with basic skills and experience. Also, it loosens the insulation and gives you a more even application – ensuring that all areas are adequately insulated.

Did you know? Blown in insulation machines are easy to use and readily available. In fact, many stores like Home Depot and Menards will loan you an insulation machine for free if you buy enough insulation – usually enough bags to fill a 1,200 square foot attic or more.

Here are your loose fill insulation materials with pros and cons of each. There is little difference in loose fill insulation cost based on material.

Pro Tip: R-values for these materials depend on many factors, primarily density but also the “mix” of the material. We tend to give average R-values – their resistance to the transfer of heat, aka their ability to insulate the space. You can find differing R-values to each material, close but not exact, wherever you look including at the other insulation articles right here on PickHVAC.com.

Blown In Fiberglass

Fiberglass insulation is the most cost-effective insulation product available. While many homeowners are more familiar with batts and rolls, it is blown in fiberglass that that has become the number one attic insulation across North America.

Fiberglass are spun, coated glass fibers that also contain air within the fibers. Those air pockets in each strand and those caused by the layering of the strands (air pockets within the fluff of the fiberglass) are deterrents to the transfer of heat.

As noted, loose fill fiberglass average cost is about $1.10 to $2.00 per square foot at 1” deep. And it has an R-value of 2.5 to 3.5 per inch of depth.

Blown In Mineral Wool

AKA rock wool or rockwool, it is spun from minerals other than glass (silica). It has a slightly higher cost of per square foot but also a better R-value of 3.0 to 3.7 per inch. Cost ranges from about $1.50 to $2.25 per square foot.

Check this out: Compare the R-value of all major insulation types in our What is R Value guide.

Blown In Cellulose

What happens to the newspaper you put in the recycling bin or take to the recycling center? A lot of it is used to produce cellulose loose fill / blown in insulation. Cellulose is wood pulp/fiber. Wood fiber is used to make newspaper. Newspaper is recycled into cellulose insulation.

It’s a nice “circle of life” for wood pulp.

Most cellulose loose fill insulation is wetted and blown into wall cavities. We have used this insulation type on several homes, and it is one of the most cost-effective insulation options available, though it’s not quite as DIY friendly as dry types.

Loose fill cellulose starts at about $1.40 per square foot per inch and has an R-value from 3.2 to 3.7.

Did you know? Insects love to munch on old newspaper. To prevent this from happening, manufacturers of blown in cellulose insulation add borate to the mix, which keeps the bugs away. Borate is the same chemical added to pressure-treated lumber to allow it to resist insects and rot. The cellulose is also treated to be fire-retardant, but the more dangerous substances like formaldehyde are no longer used.

Loose Fill Insulation Cost by Room or Home Area

We posted a chart at the top showing cost ranges from using blown in insulation in various parts of your home.

Here each is explained with tips, pros and cons and other insights we hope will help you choose the right “stuff” for your projects.

Note – Costs are for homes in size from about 1,000 square feet to 3,000 square feet, so hence the wide range of costs.

If your home is larger, do some math. For example, a 4,000 square foot home is 33% larger than a 3,000 square foot home, so multiply the cost for 3,000 square feet by 1.33.

Entire New House (Or Demo/Remodel)

Many homeowners choose different kinds of loose fill throughout their new home, new addition or gut and remodel project.

$2,600 - $7,400: That’s a standard price range for using one or more blown in insulation types throughout a home or addition.

Now, let’s look at various parts of the house with insulation prices and costs.

Walls

$1,825 - $3,3600: Wet cellulose is a great choice for wall cavities. It sticks in the vertical space, it’s best “pro.”

In an arid climate, it will dry in a few days. Elsewhere it might take a week – or you might have to bring in propane heaters to dry out the insulation more quickly as you prepare to hang and finish drywall. That’s a minor “con.”

Alternative – Fiberglass batt insulation in walls above grade and spray foam insulation in basement and crawlspace wall applications.

Attic Floors

$1,500 - $5,500: You’re looking at 8-18 inches of insulation, and the average cost can add up.

Choose your preferred blown in insulation for attics. In southern climates, insulation experts and the Department of Energy recommend an R-value of 30 to 39. Any type of loose fill will easily get you to those numbers.

In northern climates, the recommendation is up to R-60, so to get to that number with the least depth, consider premium cellulose or mineral wool. They have a slight “pro” in this respect over loose fill fiberglass.

2-car Garage

$1,375 - $3,100 should cover the wall insulation and insulation over a finished ceiling. If you have a heated garage – even if you use a space heater out there in the winter to work on the cars or other projects, adding insulation to the ceiling is a “must.”

Garage Walls

$650 - $900: Cost could go a little higher. Why would you do just the walls? Because some homeowners use rigid foam insulation in garage ceilings. They do this to easier use the space above the garage ceiling for storage, which is not recommended with loose fill.

Garage Attic Floor

$580 - $1,850: If you’re not using the space for storage, then blown in insulation is a good choice above the garage ceiling.

Crawlspace/Basement

These insulation products are not recommended for basements – expect maybe the ceiling in a very dry basement.  

Why? Because basements are poured concrete. Concrete is produced with tons of water in a typical foundation. Plus, moisture migrates through concrete into the interior space.

Here’s the bottom line: Fiberglass, mineral wool and cellulose will get damp. And when these blown in insulation types get wet, they are 1). Ineffective, and 2). They can grow mold.

Alternatives – Closed cell spray foam insulation or rigid foam board insulation that is waterproof.

How Much Blown In Insulation Do I Need?

Here is a review of R-values for loose fill insulation options.

Materials & R-value per Inch

  • Blown in Fiberglass      2.5 - 3.5
  • Blown in Rockwool      3.0 - 3.7
  • Blown in Cellulose       3.2 - 3.7

Here a few resources we’ve used in other insulation guides. The map is developed by the International Energy Conservation Code.

insulation levels map

Wall cavities in most homes are either about 3.5 inches thick when 2x4 construction is used, 5.5 inches in 2x6 construction and 7.5 in 2x8 construction.

This chart includes crawlspaces, but keep in mind that closed cell foam insulation is the right choice for basement and crawlspace applications.

Did you know? R-60 insulation is recommended in most of Florida, just as it is in Minnesota and other cold-region states.

Why? Because insulation keeps summertime heat from penetrating the attic and making your home hotter – just as it keeps warm air inside your home in winter.

Both heat entering in summer and escaping in winter will cause your home’s heating and cooling system to work harder. This will drive up energy costs and make your system work harder than it should. The result will be high bills and earlier mechanical trouble for your gas furnace, air conditioner, heat pump, etc.

Blown In Insulation Cost Factors

Cost per inch of insulation varies. What makes some loose fill fiberglass jobs $1.10 per square foot and others $2.00? These loose fill insulation price factors are used by contractors to determine their estimate – Unless you DIY.

Size of the Area – The larger the area, the higher the average cost. However, cost per square foot drops as size goes up. For example, if you have a sprawling ranch with a 2,000 square foot attic, your job is likely to be closer to $1.10 per square foot per inch. In a 1,000 square foot home, price for fiberglass loose fill insulation will be closer to $1.50. It’s economic economies of scale.

R-value – The greater the depth of insulation, the more it costs. As with size, cost goes down per inch with thicker applications because the installer is already on site with the machine set up.

Access – The harder it is to access the location, the more blown in price per square foot will be.

Removing Old Insulation – Many times, insulation gets damp due to a roof leak and has to be removed. Sagging fiberglass batts are often replaced in a remodel. Attic insulation removal cost varies – see our Attic Insulation Cost guide for details.

Who Does the Work – While we do not recommend DIY spray foam because getting an even coat that effectively seals the space is so important – loose fill is a different story, especially dry fill.

You’ll save half or more of the cost of the job by using a Home Depot blower and handling the job yourself. See the Keys to Effective Loose Fill Insulation section next.

Keys to Effective Loose Fill Insulation

There’s more to it than filling the machine and firing blown in insulation into the attic, filling the space between the roof joists – and then some. That’s most of it, but here are a few tips.

First, keep soffit vents open by using cardboard or foam baffles. They can be supplied by the retailer that sells you the insulation. Covering these vents during blown in projects is the most common mistake. And it is a costly one. When those vents are blocked, airflow in the attic is hindered, and moisture can’t escape. The result is inevitably, in humid climates, mold and rot in the attic framing.

This picture collage shows an attic in which loose fill insulation has been added over the top of fiberglass roll insulation.

  • Top center: Baffles placed inside.
  • Right picture: The fiberglass roll is lifted and held off the soffit vent by the baffle.
  • Left picture: Air is allowed to flow in through the soffit vent and out the ridge vent, taking heat and moisture with it.
Soffit Vent Baffle

Secondly, learn how to use a blow-in machine – how to fill it and apply insulation to your attic. This guide and video from Lowes are a good tutorial package.

Third, pay attention to details. For example, note the protective gear the installer is wearing? That hard hat is a great idea! Also, seal all the air gaps. Sealing from air leaks is just as important having enough insulation in the attic or other locations.

Safety issues: Then take care to follow the guidelines for furnace vent flues and can ceiling lights, both of which can get very hot and pose a fire threat. Mapping out light locations which will soon be covered is another great blown in insulation installation tip!

Wait a second! The only part of the Lowe’s project we take issue is, is the open center of the attic. What Lowe’s did was to insulate close to walls, where most heat is lost. They didn’t add extra insulation to the center – which was already covered by some insulation beneath the sheets of plywood. But most projects call for covering the entire attic floor with additional insulation.

Running the machine is the easiest part! Though having a second set of hands is imperative. Prep is the most important aspect of the project.

Pro Tip: Don’t set the airflow on the machine too high. Follow manufacturer instructions. The danger of setting airflow too high is that it “fluffs” the material more than it should. Initially, you think you have the amount of insulation you need – 14 inches deep or whatever. But in a few days to a few weeks, it settles to its “normal” density, and you’ve really got only 10 inches of insulation.

Loose Fill vs Batts and Rolls in the Attic

Loose fill wins because it fills the spaces better than batts or rolls between the joists. Energy Vanguard says, “For the best performance, an insulation material needs to fill the whole space, with no gaps, voids, compression, or incompletely filled areas. Batts are about the worst you can do here.”

Loose Cellulose vs Fiberglass vs Rockwool

Cellulose costs the most but has the most to offer too. It does a good job insulating the space, nicely covering all surface areas.

Walls: Wetted cellulose is the best option because it sticks in place. Over the years, loose fiberglass and rockwool will settle in the walls. You’ll have gaps at the top where heat can leave in winter and enter in summer.

Attics: There’s less of a clear choice here, but we’ll stick with cellulose for its additional qualities. They are well summarized by an insulation contractor with 20 years’ experience with all three. The contractor says, “Cellulose…is the only [insulation] in my home… It provides better thermal properties [than] the others except closed cell polyurethane, it beats all of the others for stopping sound transmission.” He goes on to say he believes cellulose has a better fire rating than the others because it is treated to be fire-resistant.

The bottom line is that it is worth getting estimates from several contractor. Ask if they agree with this assessment. Take your budget into consideration, and get estimates on various materials. The process will help you decide which material is the best for each location in your home.

See more below on getting estimates.

What About Spray Foam In the Attic?

If you’re sealing the attic entirely – no airflow at all – you’ll need to use SPF spray foam.

If not, spray foam is a waste of money. In our Spray Foam Insulation Cost and Ultimate Guide, there is a useful section on Spray Foam vs Fiberglass plus clear guidance on when foam is better and when fiberglass is the right choice.

Energy Rebates for Upgrading Insulation

Did you know that many energy companies are providing rebates to customers that upgrade their home’s insulation and in other ways make them more efficient?

These energy companies have a mandate to assist customers in cutting energy use. For example, DTE Energy is offering, “up to $125 in cash-back rebates for installing energy-efficient insulation.” That’s just one of hundreds of energy providers that will pay you back to improve your home’s energy efficiency.

And if it is time to replace your outdated thermostat with a smart or wi-fi thermostat, DTE is like many companies offering rebates on them – in this case, $50. Check out our Smart Thermostat Guide for today’s top WiFi enabled smart thermostats.

Getting Estimates from Contractors

It’s always a good idea to request written estimates from 3 or more local contractors.

It isn’t just about the bottom line – blown in insulation cost. During the process of getting estimates, you can discuss what type of insulation will be used – and why that’s the right product.

If you’re doing a whole house and it has a basement or crawlspace, then multiple materials might be recommended.

When you find a contractor you think is a good fit, check out their online Google and Better Business Bureau reviews and file. Make sure they have a good reputation and are licensed and insured to protect you in the event of problems.

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