Cellulose vs. Fiberglass Insulation

We’ve gone into relative depth as of late regarding the application of insulation in your home. We’ve talked about where you should be sure to insulate thoroughly, and we’ve touched a good bit on cellulose blown-in insulation. Today we’d like to tackle a bit of a related hornet’s nest: which is better between cellulose insulation and fiberglass batts?

What Are Cellulose & Fiberglass Insulation?

To start things off it’d be best to define what these two things even are:

Cellulose insulation is made up of waste paper fibers—primarily newsprint and similar materials. The fibers are treated with a fire-retardant (up to roughly 15% borax and other non-toxic retardants) and fabricated to be used in a process called blown-in insulation.

Fiberglass is made up of recycled glass woven into very very thin and fine coarse weaves. The material is fitted with a backing and made into batts, which are relatively easy to install rolls of insulation.

Which of the Two Is Better?

A very, very old debate, and one that still goes on to this day. The easiest answer is “whichever is best for your project or needs.” But that’s a bit of a cop-out, isn’t it? To really understand what we’re looking at we have to take it from the angles that matter to you. Namely, cost, effectiveness, and safety. So let’s do exactly that!


Where cost is involved there is actually little difference on the surface. Both of these materials are quite heavily supplied and very cost-effective, making them readily available and suitable for most home applications. Fiberglass is typically slightly cheaper, but that fact has to be weighed against cellulose’s slightly higher efficiency (which we’ll cover in a moment) and longer overall lifespan. A professional cellulose blown-in insulation will often last as long as the home does, making it cheaper by longevity.


Once again the argument seems a wee bit apples to apples, since if you look at R-values alone you’ll see very little difference. But there’s actually a pretty big point hiding underneath: while neither of these insulation types offers a complete air barrier, cellulose does in fact slow the movement of air, and thus reduces thermal transfer. Fiberglass on the other hand has absolutely no power over air movement, making energy loss noteworthy in its use.


Neither of these materials is harmful to humans at all, so there are no worries there. That just leaves fire, which is a point worth making for sure. Fiberglass is simply woven glass, and will melt rather than burn. But! Fiberglass is backed with what is essentially paper rolls to form the batts, and this paper is very flammable.

Cellulose is treated specifically with borates in considerable concentrations so that it is virtually completely flame-resistant, making it overall safer in the end when it comes to slowing fire spread and reducing property loss.

Insulation Services in Orlando, FL

Overall our professionals find cellulose to last a bit longer, perform better overall, and be a more complete solution in the end. If you’d like to find out more reasons to install cellulose insulation we would encourage you to check out our articles on the topic! Or if you’re ready to gain the advantages of blown-in cellulose for your home, feel free to contact us online for your quote!