BLOWN-IN
INSULATION
GUIDE
Blown-in insulation is a different process than other forms of insulation. Where batt or roll insulation is measured, cut, and laid methodically, blown-in insulation is simply sprayed into a space using compressed air. Despite this, it offers many of the same benefits as other forms of insulation – often best in conjunction with other insulation types.
In fact, blown-in insulation is a more precise process than it seems. To the naked eye, it looks as if you are simply spraying fiberglass or cellulose insulation products randomly into an empty space. However, there is a lot more science and expertise behind the process.
Fiberglass is made from molten glass that has been turned into fibers through the use of compressed air or complex spinning processes. Increasingly, fiberglass is using recycled glass – most manufacturers use between 40-60% recycled material in their fiberglass.
WHAT IS
BLOWN-IN INSULATION
As the name suggests, ‘blown-in’ insulation is small, loose fragments of insulation that are sprayed into a space using compressed air. This allows for loose space to be filled quickly and efficiently. Usually, blown-in insulation is used as a ‘top-off,’ in conjunction with other insulation types.
WHAT IS IT MADE OF?
There are two main types of blown-in insulation. The first is made of fiberglass, and the second is an organic cellulose composition. Here are the differences between the two.
CELLULOSE
Immediately after installation, the cellulose insulation has a higher R-value (the value that denotes the insulating effectiveness of different materials).
However, as it is an organic material, it experiences some level of decay and ‘settling’ over time. This means that its R-value gradually diminishes.
FIBERGLASS
By contrast, fiberglass insulation retains the same insulating properties without deterioration.
In general, despite the settling of cellulose insulation, there is very little difference in R-value between the two materials. The key factor in how well they provide insulating properties is the skill with which it is installed.
Things that can reduce the effectiveness of blown-in insulation:
- Leaving gaps
- Overfilling some areas
- Not using a dense enough covering
For those reasons, it’s better to have a professional install any blown-in insulation.
USES
The most common usage of blown-in insulation is as a top off to fiberglass rolls or batt insulation. For example, if your attic space already contains insulation, but you wish to reinforce it or provide additional insulation, topping it off with blown-in may be the best option (and certainly cheaper than replacing the existing insulation).
If the existing insulation is dry, clean, and uncontaminated, you can add blown-in insulation with no problems. If the existing batts or rolls are damaged, they may need to be replaced before blown-in insulation is added.
BENEFITS OF
BLOWN-IN
INSULATION
Blown-in insulation has a number of benefits for homeowners. As mentioned above, blown-in insulation works well in conjunction with batts or rolls, meaning you can supplement your existing insulation with it.
The benefits include the following:
Cost-Effective
The most common reason why blown-in insulation is used is that it is an extremely cost-effective way to increase the overall R-value of your space. Blown-in insulation can pay for itself very quickly in reduced heating costs for your home.
In addition, it also increases the lifespan of your existing insulation, thereby delaying any replacement costs. For a full breakdown of the costs involved, see our guide Average Cost of Blown-in Insulation.
Energy Efficiency
Fairly intuitively, installing additional insulation makes your home more energy-efficient. Blown-in insulation allows you to fill in all cracks and crevices, thus providing more comprehensive coverage of insulation – particularly in a large space like your attic. Insulation also helps to keep cool air in during the summer, meaning you get savings throughout the year.
Noise
Blown-in insulation also insulates against sound. The same process that prevents heat from passing through goes a long way towards dampening against sound. This can be beneficial when placed in a wall cavity.
Ease of Installation
If a professional installs the blown-in installation (and uses all the correct equipment) it is an extremely quick process – particularly in comparison with other insulation types. The added effect of the easy installation is that costs are lowered since contractors work fewer hours.
Comprehensive Coverage
If you are insulating a space such as an attic that contains a number of awkward shapes – crossbeams, plumbing pipes, wiring, and ductwork – you are likely to find it tricky to install either rolls or batts while also ensuring equal coverage across the space. Put another way, you are bound to leave gaps. Blown-in insulation overcomes that. The smaller particles cover all awkward shapes and provide comprehensive insulation coverage.
Appliance Running Costs
If you increase your home’s energy efficiency, you will decrease the work done by the HVAC system throughout the year. This has secondary savings, as your appliances will cost less to run, and will last longer.
If you can make your HVAC system last even one year longer as a result of additional insulation, you will have saved hundreds, if not thousands of dollars. This is on top of the reduced utility bills you get from increased energy efficiency.
Fire Resistance
Blown-in insulation is manufactured to be fire-resistant. This is extremely important when it comes to installation in your home – any non-fire-resistant material can be extremely hazardous, particularly when placed in cavities such as attics. Fiberglass is, in general, somewhat fire-resistant; cellulose insulation is treated in order to make it fire-resistant.
LIMITATIONS OF BLOWN-IN INSULATION
Of course, there are some weaknesses of blown-in insulation that it’s critical to know before installing it. These include the following:
REACTION TO MOISTURE
If blown-in cellulose gets wet, it takes an extremely long time to dry out and in some cases it doesn’t dry out at all. If your roof leaks or you have moisture in your walls, this can very quickly saturate your insulation and cause it to rot.
MOLD
Connected with the issue of dampness is that of mold. Cellulose is a favorite food of mold and mildew and, while most insulation materials are treated with mold-repelling additives, they are not always able to prevent mold from forming.
Once the cellulose does get moldy, it is an extremely laborious process to remove it.
LIMITATIONS TO ITS FIRE RESISTANCE
Although blown-in insulation is treated to be fireproof (and has to pass rigorous safety standards to ensure it is not flammable) as mentioned above, in cases of high heat or fire it can smolder. This can cause major damage, not just to the insulation, but to any other materials around it.
In cases of high heat, for example around a light fitting, this may be problematic and it’s certainly something to be aware of.
COMPARING BLOWN-IN INSULATION
WITH OTHER INSULATION TYPES
Comparing batts and rolls of fiberglass is relatively intuitive because the two have broadly similar appearances and are more or less the same material. Doing the same with blown-in insulation is trickier.
However, it’s important to understand what’s involved with blown-in insulation if you are to make the best financial decision when it comes to installation.
INSTALLATION
As mentioned above, installation for blown-in insulation is speedy because it’s literally sprayed into your home using compressed air (the actual mechanics of it look like using a hose full of home). However, unlike batt or rolls, you will almost certainly need a professional to install it. Batts or rolls can be tricky to install, but an amateur can certainly do it.
For installation, you can expect to pay somewhere between $40 and $70 per hour for a professional team to work the job. However, this usually doesn’t take more than a couple of hours (depending on the size of the space).
MATERIAL COST
Despite its dramatically different appearance, blown-in insulation ends up costing about the same as other forms of insulation with comparable R-values. For example, a 19-lb bag of blown-in cellulose costs around $30; this will cover around 40 square feet.
This means that a typical attic will cost between $600 and $1,200 to cover with blown-in insulation. This is roughly the same as with batts or fiberglass rolls.
R-VALUE
A typical fiberglass batt will have an R-value of around 3.7 per inch. Blown-in cellulose usually offers between 3.2 and 3.8 per inch, giving roughly the same amount of insulation.
To learn more about R-value, go to our what is insulation r-value page.
In the vast majority of cases, choosing blown-in insulation is a supplement, not a comparison.
You add blown-in insulation either in addition to batts or rolled fiberglass, or you install it in parts of your home that batts or rolls couldn’t fit anyway.
Therefore, the question when it comes to blown-in insulation is one of cost and necessity. What this guide has shown is that there are a number of advantages when it comes to the use of blown-in insulation.
These include:
Greater energy efficiency
Reduced utility bills
Sound insulation
Each of these stems from blown-in insulation’s ability to fill gaps in coverage as well as to shore up existing insulation. In effect, it provides a second layer of insulation.
Whether or not to install blown-in insulation is, therefore, a purely financial matter. Does the cost of installation exceed the savings? If the answer is no, then it’s time to make the investment. Your utility bill, your carbon footprint, and your home’s value will all thank you for it.