Blown-in insulation is one of the most DIY-friendly and cost effective ways you can insulate a house today. It can be a little messy but that shouldn’t discourage you from doing it yourself because the energy savings that you can get from one day of work will continue to pay for themselves year after year.
Combine the energy savings with the low cost of the materials unlike options like mineral wool or spray foam and you’ve got the perfect insulation for almost any attic. Most places where you can purchase blown-in insulation will even give you a free machine to use when you purchase your insulation from them.
There is no measuring and cutting and no waste unlike with batts. Blown-in insulation is as simple as it gets when it comes to insulating a house. It does have its limitations though and it isn’t perfect for every location or every house so keep reading to see if it is right for your situation and how to do it.
Types of Blown-in Insulation
There are two main options when it comes to blown-in insulation in most of the country.
Both options provide similar R-values but there are some notable differences that I think make the decision a no-brainer. I have used both and I greatly prefer using cellulose for a few reasons:
- 57% more fire-resistant than fiberglass
- Uses 10 times less energy to manufacture than fiberglass
- Made from 85% recycled materials
- Itch-free installation with no known adverse health effects
- Better insulator against convective heat than fiberglass
Those are some serious advantages in the favor of cellulose! When I insulated my house, I had no agenda other than to get the most bang for my buck in terms of insulating power and use the most eco-friendly product. Cellulose meets both of those requirements.
How Much Insulation Do I Need?
The easiest way to get started is in your attic. For most climates, adding a thick layer of insulation here will give you the greatest return on your investment.
How much insulation do you need? For most areas of the country, R-30 is the bare minimum, but you should definitely go higher than that, especially in colder climates.
Cellulose insulation is pretty affordable (around $12 per bag) and while you have the machine and you’re already getting messy, I would add as much insulation as possible.
Click on the map below to see the recommended R-values for your area.
How to Install Blown-in Insulation
Let’s start talking nuts and bolts here. You will need the following things to get the work done:
- Cellulose (duh!)
- Blowing machine
- Safety glasses
- Respirator or dust mask
Cellulose insulation isn’t a health hazard, but installing blown-in insulation does make a dusty mess and you want to protect your eyes and avoid breathing the dust filled air as much as possible. You also don’t need to worry about wearing long sleeves since cellulose doesn’t make you itchy like fiberglass.
Setting up the Blower
I’m sure other hardware stores have similar deals, but I have to give Home Depot credit on this one. They will give you a free rental of an insulation blower if you purchase 20 bags or more of insulation. Not bad!
The blower comes with a long hose so you don’t have to haul it up the stairs if you don’t want to (which I don’t recommend because this thing is a heavy beast).
Setting up the blower is pretty straight forward. You just attach the hose, plug it in, and load some insulation into the hopper. You will need a helper to keep loading bags into the machine while you use the hose to direct the insulation where you want it, otherwise you will be crawling back to the hopper every 5 minutes.
Let it Blow
You’ll need to install the cellulose all across the attic floor starting from the furthest sections and working your way back to the exit. Blowing in insulation in this manner will give you what’s called “loose-fill” insulation.
The power of loose-fill is in its ability to slow down air and heat transfer through the thick fluffy blanket you blow in. This is different from “dense-pack” installation methods which are a little more complicated.
That being said, your goal here is to create the fluffiest covering of cellulose you can. Don’t blow it in and try to pack it down. It will settle a bit over time so always fill more than you think you should. When I say fill more than you think go big because the settlement factor over that first 6 months to a year is big! I lost about 4 inches to settlement and wish I had installed more.
I would recommend a minimum of 10″ of loose fill for an attic floor, which should give you about an R-30 rating. But like I said earlier, if you’re gonna do it, you might as well do it right and add as much as you can.
What’s the Cost?
To give you an idea of how much insulation you’ll need, GreenFiber has a coverage chart on their website to help you do the math. I found that the chart is pretty much right on.
For my 1300 SF house, I decided to get about an R-36 rating which required about 45 bags in my case. I could have done more but we already have spray foam on the underside of the roof deck so that put me at a total of about R-43 in the attic, which is well above what is recommended for our Florida climate.
It took me one full, very dirty day to get it all done and cost me $581.33. For that price, I can make that money back in energy savings easily within the first year. After that first year, that’s money in my pocket!
So, if you haven’t already done it, put some insulation on that attic floor. Maybe you’ll get to insulating the walls someday, but the place to start is where you’ll get the most bang for your buck with the least possible downside, and that’s the attic.
Founder & Senior Editor
I love old houses, working with my hands, and teaching others the excitment of doing it yourself! Everything is teachable if you only give it the chance.