What Is Blown-in Insulation And How Much Does It Cost

For houses with poorly insulated walls, floors, ceilings, or attics, blown-in Insulation is one very important way to keep the home warm.

In most of the newly built houses, the furnace does not work overtime, and neither does the water pipe run the risk of freezing or breaking. This is because most of these houses already have a properly planned insulation system. And hence, they only need a minimum amount of extra insulation. However, this is not usually the case with many older houses. Older houses are mostly under-insulated and they require frequent layerings of insulation in the walls and attics- thereby requiring the blown-in insulation.

Blown-in insulation is tiny pieces of insulating materials blown into the walls and other parts of the house through a long hose. The most common insulating materials used for this are fiberglass and cellulose. The cost of blown-in insulation typically varies from $10 and $150 per bag. 

Blown-in Insulation is a secondary insulation method. It is corrective and targets the tiny loops and holes that sip cold into the house. It comes with a great deal of flexibility. 

This article will extensively discuss the peculiarities of the blown-in insulation, its types, some of its uses, its installation process, and will discuss a few tips that ensure a seamless installation process.

a person installing blown insulation

The Peculiarities of the Blown-in Insulation

There are different factors that distinguish blown-in insulation from other types of insulation. But I will make a list of the very important ones.

Ease and flexibility

Among the many categorizations of insulation types, the Blown-in insulation is the easiest and quickest to work into an existing wall stud or ceiling joist. The Batt Insulation comes close, but it doesn’t go through a seamless and easy process as Blown-in Insulation does.

Batt Insulation fits perfectly during new construction in the home. It involves the use of thick strips of spun fiberglass in between wall studs and ceiling joists before the wallboard is mounted. However, mounting the batt insulation into an existing home will involve the expensive, tedious, and time-consuming process of first pulling down the drywall. Meanwhile, blown-in insulation only needs to be blown into the drywall without pulling fixtures down. 

The covering of small gaps in the home, sneaky spots, and soundproofing are some of the featured uses of the blown-in insulation. And this comes with a hassle-free process.

The longevity of its efficiency

The blown-in insulation does not have a long span like many of the other types of insulation. After about 5 years (depending on the coldness of the location), the blown-in insulation may get saggy and eventually fall by a few inches. This effect causes a reduction in the overall thermal resistance of the insulation. Hence, users are forced to replace the insulation more frequently than when compared to batt insulation and some others.

The Types of Blown-in Insulation

Blown-in insulation comes in three different types. 

Loose-fill Fiberglass:

This type of insulation is lightweight. It is sourced from liquid glass that has been processed into thin fibers.

It offers an average R-2.5 thermal value per inch. Hence, you’ll require 7.5 inches of blown-in insulation to get the insulating value of a batt of R-19 insulation. And the 7.5 inches of loose-fill fiberglass is priced at $35 dollars.


Cellulose insulation is sourced from paper. Either from finely shredded recycled cardboard or from newspapers. It is one of the most commonly used and accessible insulation. It is chemically treated, fire-resistant and mold-resistant. However, the cellulose insulation may lose its potency with water from leaky roofs or pipes. Water leads to sogginess and compactness, and this reduces its R-value.

It has a thicker mass with an average thermal value of R-3.7. So, only about five inches of the cellulose insulation will equal batt’s R-19. A bag of cellulose costs around $11.50.

Rock Wool:

The rock wool is also called “mineral wool.” It is sourced from blast furnace slag and spun into an airy product with a texture like the raw sheep’s wool. It has a thermal value of R-3.3 per inch, and a single bag has an approximate price of $140.

Although expensive, it has enjoyed preference as a result of its fire-resistant feature.

The Uses of the Blown-in Insulation

1. Regulates temperature

This is the primary use of Blown-in insulation. It is used to control the transfer of temperature into and out of the home. Like other insulation types, it has an R-value that makes it suitable for certain areas. It, however, has a thinner mass hence, its thermal value is also low. So, it is mostly used to correct secondary temperature leaks like small holes in existing wall studs or ceiling joists.

2. Soundproofing

Blown-in insulation can be added to attics and walls to reduce the noise from the street that comes in through the small spaces on the wall or attic. And it also contains the sound within the house and prevents personal discussions from getting outside. Hence, it is a good soundproof material.

Tips to executing seamless Blown-in insulation

Engage a second hand

The process of installing blown-in insulation can not be executed by a single person. Help is needed in filling the blowers with bags of insulation material, while the primary operator distributes the insulation with a long hose.

When a single individual runs the process, it becomes slow, inefficient, and messy.

Use a protective gear 

The blown-in insulation follows a potentially messy process. To avoid messing up yourself, it is advised that you use protective eyewear, a dust mask, gloves, and some old clothing.

Look out for joists in the attic 

While filling in the insulation, avoid standing in joists. They are not designed to carry your weight. You run the risk of a fall or accidents when you do. Improve your balance with two plywoods (2 x 3 feet) arranged across the joists.

Avoid the heat from recessed lights 

Do not use naked bulbs or sources of light while fixing your Insulation. Remember that insulation is used to trap in temperature and prevent cold from sipping in. So, this is the exact effect that you will get with the dissipated heat from the recessed light. 

What this means is that heat will get trapped in the attic while you work and if it gets too hot you run the risk of burning the bulb prematurely and this may pose a slight fire risk especially in the case where the cellulose insulation is being used.

Therefore, the way out is to box your source of light so it does not give off direct heat. Use scrap plywood or wallboard to build a hedge around each recessed light, giving a distance of about three inches between the light and the hedge. You can do this for electrical junction boxes too.


Given below is a video showing how to install blown-in insulation;

Charles John

A novice DIYer who learns about home ventilation. I am a mechanical engineer and have a basic knowledge of HVAC systems but I learn continuously to make myself the best blogger in that space.

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