When it Comes to Equipment, Fiberglass and Cellulose Are Not the Same

While we may use the same machines for blowing fiberglass and cellulose insulation, few installers realize these two materials actually require different machine settings and maintenance. As someone who has problem-solved blowing equipment issues for over 20 years, I wanted to share the main differences between blowing fiberglass and cellulose. Believe me, they’re not the same.

First off, fiberglass and cellulose are packaged differently. Fiberglass is packed denser, allowing for greater coverage per bag. That means more square feet of material can be loaded on a truck. More material means fewer trips driving back to the shop for reloading throughout the day. Not to mention, running back to anywhere results in hundreds of dollars of lost profit or margin.
Because fiberglass is packed denser, you’d expect it to need more conditioning in order to achieve coverage. Nope. In fact, it requires less because of the way fiberglass expands (cellulose does not expand) when the package is opened. This is why blown-in fiberglass installs faster than cellulose. This reduces both labor costs and wear and tear on equipment. For example, when filling the machine, crew members have to open and load around three bags of cellulose for every one bag of fiberglass. It’s also faster for the guys in the attic. This means they spend less time finding trusses to stand on, and less time sweating or freezing in the attic. It’s a win/win for everyone.

So back to those machine settings. Every machine has two basic machine settings, material feed gate and blowing pressure. Some machines may have different engine RPM settings or gear reducers, but they all have the feed gate and blower pressure. When blowing attics a good starting point is to have your material feed gate 75% open. This slows the feeding of material which gives the machine agitators more time to break up the material and increases coverage. For cellulose, close the gate another 10-15% so the material can be agitated longer to get coverage. For example, if you’re using a machine with a 16” feed gate, a good starting point for fiberglass would be 12” and 8”-10” for cellulose. There range given for cellulose, is because there are so many different bag weights due to changes in density. The denser the cellulose bag is, the less open the material feed gate should be. As for the blower settings, we want to aim for a 10’ arc of material blowing out the end of the hose.

A common problem with cellulose is plastic and other debris in the material which will build upon the agitators. This restricts the agitation to the material, reduces coverage, which more material for your project. With cellulose, let the material run low in the machine so you can inspect the agitators and clean them when needed. Be sure not to let it build up. Clean agitators condition better so you use less material. ALWAYS make sure the machine is completely shut down before you begin to clean off the agitators. Some machines require you to climb completely inside of the hopper to reach all of the agitators. This is dangerous and adds additional time to the maintenance of the equipment. Disconnect or disable all power sources to the machine before starting.

Besides a faster install, fiberglass is cleaner, and every installer knows it. Blowing cellulose creates so much dust that it becomes difficult to see in the attic during an installation. Many installers have needed to stop, just let the dust settle before they can continue blowing. The dusty conditions even continue inside the truck, where it wreaks havoc on their blowing equipment. Blowing machines need fresh air to operate efficiently. When dust gets into a motor or engine, especially where clean air is required, you can expect issues. Cellulose dust in, or on, any motor restricts airflow from cooling components. It also reduces the airflow required to generate blowing pressure for the installation. Once again, this slows down production and costs money. But the problems don’t end there. When the dust from the cellulose insulation coats components on the machine, it holds in heat. This excessive heat causes premature failure for various parts of the machine. Failure equals downtime, and downtime is one of the biggest costs to owning equipment. Whenever your blowing machine can’t be used, you’re not making money.

In summary, the main differences between blowing fiberglass and cellulose are slower install times, dusty work environments, and more equipment breakdowns, and we break it down in this video. Everyone knows installers prefer working with efficient, clean products, and using equipment that doesn’t break down. Finding good employees is hard. Keeping employees is even harder when they don’t like the experience. Either way, making money is the goal. When deciding what to install, choosing a product that offers fewer breakdowns, faster installs, and a better crew experience, seems like a pretty clear choice.

If you have questions on equipment settings, fiberglass, or any of the products we carry, be sure to reach out to your local branch or contact any of us at IDI. Our goal is to help you grow profitably and we look forward to earning your business every day.


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