Cost of GreenFiber Vs Atticat Blown In Insulation

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The recent cold snaps here in the Northeast got me thinking of adding insulation to my walls and attic. Most of it would need to be blown in and there are two options available through the big box stores. GreenFiber Cellulose Insulation and Owens Corning AttiCat Fiberglass insulation. At first glance GreenFiber may seem much cheaper since a package sells for about 1/3rd the price of AttiCat but when you add everything up, AttiCat is actually the cheaper choice. Let's look at why.

First let me say there's a lot of  competing information on which is better, fiberglass or cellulose insulation. Both can be blown into existing walls and attics without significant demolition. The people who mainly sell and install cellulose insulation think it's worlds better than fiberglass and those that manufacture and install fiberglass insulation think that's the best choice. I'm still trying to make up my mind what to believe but both options can be DIY projects and both choices offer a free blower rental with a minimum purchase from Home Depot.

Insulation recommendations changed a few years ago. If your home was built before 1990 there's a good chance you don't have enough attic insulation. If the level of insulation in your attic is at or below the floor joists, you don't have enough. If you can't see your floor joists in the attic because they're covered with insulation you're probably good.

If your home was built before 1980 you may not have any insulation in your walls. If your home was built before 1960 you more than likely don't have insulation in your walls. There's really no way to tell without making a small inspection hole in an exterior wall and visually checking.

To add insulation to existing walls without having to tear down all the drywall the only two affordable choices are blown-in fiberglass or cellulose insulation. Foam is way too expensive for me right now.

Here's what cellulose and fiberglass insulation is currently selling for at Home Depot in my area:

$11.48 for GreenFiber Blown-In Cellulose Insulation
$29.68 for Owens Corning AttiCat Fiberglass Expanding Blown-In Insulation System

When I first saw those numbers I got excited and thought I could blow in cellulose for a lot cheaper than I previously priced fiberglass. Unfortunately you need a lot more cellulose packages than you do fiberglass because the fiberglass is compressed. When it comes to walls it gets even worse which I'll explain after we look at the numbers for attics. Let's say we have a 1,000 sq ft attic we want to insulate by adding an additional R-30 worth of insulation. Here's what the numbers look like.

Attic Insulation Cost Comparison

InsulationPkgs NeededPrice/PkgTotalSavings
GreenFiber R-3044$11.48$505.12
AttiCat R-3016$29.68$474.88$30.24 (5.99%)
OC Fiberglass R-30 Batts29$15.98$463.42$41.70 (8.26%)
GreenFiber R-3859$11.48$677.32
AttiCat R-3820$29.68$593.60$83.72 (12.36%)
GreenFiber R-4981$11.48$929.88
AttiCat R-4926$29.68$771.68$158.20 (17.01%)

The costs above only reflect the cost of the insulation. You get a free 24 hour blower rental if you buy 20 bags of GreenFiber or 10 bags of AttiCat and we're above both of those and I assumed you'd need to rent a truck for either if you don't already have one. Although you're getting a lot more packages of GreenFiber so for some people, that may mean having to rent the HD truck instead of using their own truck.


If you're only adding an additional R-30's worth of insulation the cheapest option is to use Unfaced R-30 Batts that you just roll over your existing installation (perpendicular to your joists.) if you don't mind crawling around cutting insulation.

If you'd rather blow insulation, AttiCat is slightly less than GreenFiber and not much more than R-30 rolls. Not a big enough difference to choose one over the other if you have a certain preference for either fiberglass or cellulose in my opinion.

R-38 and R-49

If you want to add an additional R-38 worth of insulation or more you really start to see significant savings with AttiCat. For some reason, GreenFiber's recommendations aren't linear. You need proportionally more insulation as you increase R-Value.

At R-30 you need about 2.75 times as many GreenFiber bags as you need AttiCat. At R-38 it's 2.95 times more and at R-49 it's over 3.1 times as many packages.

I think the labor will become an issue as well with cellulose. You have to load, unload, carry and feed about 3 times as many bags of GreenFiber as you do AttiCat.

Wall Insulation Cost Comparison

The following table compares the price for 2,000 square feet of 2x4 framed exterior walls.

InsulationPkgs NeededPrice/PkgTotalSavings
GreenFiber R-1398$11.48$1,125.04
AttiCat R-1327$29.68$801.68$323.68 (28.77%)
AttiCat R-1531$29.68$920.08$204.96 (25.58%)

Things get a lot worse for cellulose insulation when it comes to blowing into existing walls. When installing blown-in insulation in walls you have to blow it in at a higher density than you do for attic installations.

This is true for both cellulose and fiberglass but fiberglass only needs double the amount while cellulose needs triple the amount. With AttiCat you also have the option to add a little more to get a higher R-15 insulation rating. With cellulose you'd probably start busting through your drywall?

Cellulose insulation settles a little bit compared to fiberglass so you really have to pack it in. When you do that, the settling is minimal. I'm guessing that's why it takes much more cellulose insulation compared to fiberglass.

You're saving a lot more money on material cost with fiberglass than with cellulose insulation even if you choose to go with the R-15 installation option of AttiCat. You're also dealing with about 1/3rd as many packages of insulation.


There are pros and cons to each but it's a bit difficult to discern what's truth and what's marketing. For example fiberglass is more affordable and provides good insulation but is itchy. Cellulose is treated with borates which makes it fire retardant and may repel pests and mold. It can be as much as three times heavier than fiberglass which could be an issue in some structures and if not installed to the correct density it can slump over the years leaving an uninsulated void at the top of the wall cavity.

Either GreenFiber or AttiCat is going to be better than not having enough attic insulation or any insulation in your walls if you live in a colder climate. Both can be installed by DIY'ers who spend time reading the instructions and preparing beforehand.

For adding insulation to your attic at R-30 they're similar in cost but as you go deeper you realize more savings with AtticCat.

For adding insulation to existing walls you can save close to 30% with AtticCat versus GreenFiber and you'll need to deal with about 1/3rd as many packages of insulation. They're similar in size but the AtticCat is heavier because it's compressed. Still I think having to open and load that many more packages into the blower is going to get tiring and possibly slow things down.

You can get a free blower rental with either so other costs should be similar.

The numbers I calculated are from current prices in my area. Check to see what GreenFiber
and AttiCat is selling for in your area before you make any decisions.


  1. Thank you for sharing this! I've been trying to make up my mind between the blown fiberglass or cellulose for my attic and didn't realize cellulose takes so many more bags. The difference in labor, combined with not really such a dramatic price difference after all, makes it much easier to decide. ;)

  2. I used green fiber over my garage. I Really liked the noise reduction since I play music I dont think fiberglass would have that benifit.
    I am now thinking of using green fiber for my walls, however Ive read that the machines at the home improvement stores do not supply enough pressure for that.

    1. Jeremy,

      Fiberglass will help with sound but I don't think as much. Each product has it's strengths for different applications. All I really cared about for my home was reducing heat loss/gain, ease of installation and cost. At first I thought cellulose would be cheaper because the bags were so much cheaper until I realized how many more bags you would need.

      Not sure about the machines available for rent and if they can do blown in cellulose in walls. Cellulose needs to be packed denser in walls and might require more skill to achieve that. You can contact the store to find out the model number and maybe contact the manufacturer to see if it can dense pack in walls.

    2. Fiberglass does not offer ANY sound reduction. I'm going with cellulose and will pay the additional costs to get the noise reduction and no air seepage.

  3. Do your own calculations. Here Green Fiber is $7.25/bag while Atticat is $31.97/bag. So Atticat would cost me $181.15 more for 1,000 sqft. A huge difference opposite of the authors.

  4. Thanks for the updated prices. I just looked again in my area and there is now some bulk pricing discounts. $8.04 for GF if you buy 100 bags or more, $22.38 for AC if you buy 30 bags or more.

  5. Cellulose is far superior to fiberglass in insulation properties. Fiberglass will allow air penetration whereas cellulose, if properly installed, will not. It doesn't matter how you install fiberglass, you will have air infiltration. And the added bonuses of noise reduction and fire retardant makes cellulose the only choice. If you want to see how a building burns with cellulose vs fiberglass, a quick google will show various videos. I/m getting ready to insulate my house, walls and attic, and will pay a couple extra hundred for the better product.

  6. Fiberglass or Cellulose - money is not my concern. I have heard that fiberglass my be carcinogenic. However, one of my local contractors said that the new product is not a problem since they have reformulated it. What's your take on this?

    Steve K.

  7. The greenfiber definitely is not good materials for the house chilling at all. I just got a company came my home to replaced all instalation in my roof today, and I found that material very bad feeling when you touch and bad paper burning all when I try to burn it also it even can Burned to dark aish ( no flame) and my room had terrible buying trush small! Really it is the worst mayoral I compare with my original material fiber glass !!

  8. I used AtiCat in my previous home. It was good for keeping heat loss at a minimum and I think it is very good. Four years later I had a house built and I blew in GreenFiber insulation in between the wall and attic. Tom is right, it took 3 times the amount of bags for a 2300 sq.ft. GF takes more work and $$, but it did keep the house completely free of air flow between cracks and small openings around the house. Another thing I noticed is the rooms are a lot more quiet; I can't hear noise from the next room, but then again, I do have 6" thick walls compared to my previous 4". GF is a bit heavier, too. After 4 months, I went into the attic to see how the insulation was faring and it seemed to have slumped at wall junctions. I refilled that area with 7 extra bags. It's been almost 3 years, now, and I've had no problems with it. The layer is still there. I haven't had any insect or rodent problems (squirrels), and I've used about 38% of electricity on AC compared to my smaller house. I'm renting my older house and I had to redo sections of the AtiCat insulation. I think it is squirrels and birds that get inside and make tunnels.

    AtiCat is cheaper and easier to install, but in the long run, GF has lasted much more with added benefits. Also, GF is no longer 100% paper as advertised, it is 85%, now. I guess the added Boric and Ammonium make up the rest, which is why I assume it's so dense. The bad thing about it being so dense is if it gets wet, it will create a smell that will last for weeks or a couple of months. I didn't realize where the smell came from until I saw the leak from the roof. The good thing is the insulation absorbed all of the rain water and the sheet-rock didn't get wet. Many pros and cons, but I'm a little happier with GF despite the price and work. I hope this helps.

  9. For attic spaces, especially if you have trusses, I would always go with blown insulation. I recently did one wing of my house 24 x 40 feet -- typical 1:3 truss so I had about 4 feet between the top of bottom chord and the bottom of the top chord to work in.

    Existing bats didn't quite come to the top of the rafters.

    Once I did all the prep work, mostly checking and sealing light boxes, and putting new vapour barrier over the bathroom fan so if I have to replace it, I don't get a face full of insulation (sometimes I think ahead...) Anyway the whole thing only took about 2 hours. Blown in fills all the corners, nooks, gaps in the bats....

    With a product like this, transportation is a big factor. The relative price of cellulose vs fiberglass is going to depend on how many miles it is to the factory, and whether your dealer can buy in freight car rather than semi trailer loads.
    I went with cellulose.

    A: I caught a 3 for 2 sale so it was 2/3 the price.

    B: Environmentally it's a better bet -- recycling newspaper and cardboard takes far less energy than melting glass.

    C: Water on cellulose soaks the surface, and has a chance to dry out. Water on fiberglass passes through the glass and sits on top of the vapour barrier for at least a forever.

    D: I'm not scratching for 3 days after working with cellulose.

  10. I used blown in cellulose to insulate my attic. It was hard work hauling and lifting it. My helper and I went through a dozen dust masks and were covered in dust and flame retardant.
    Later, we insulated another attic with Atticat fiberglas. It was about half as much work and much cleaner, one dust mask each was good for the entire job. The fiberglas does not cause itching like the old fiberglas batts did.
    So, I will never use cellulose insulation again!