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When Choosing Loose Fill Insulation, Which is Best: Cellulose or Fiberglass?

“I would definitely recommend cellulose loose fill insulation,” says one home improvement contractor. “I would choose fiberglass loose fill insulation,” says another. Sound familiar? Chances are, if you are looking at installing new insulation in your home, you will have heard many different opinions on loose fill insulation and which is ultimately the best. Unfortunately, many home improvement contractors out there will attempt to sell you on loose fill insulation based on the materials they sell, with their opinions being heavily influenced by the materials they offer rather than actual facts. At Windows on Washington, we have installed all types of insulation, which is why we make our recommendations for which loose fill insulation is best based on the results we have achieved in our clients’ homes. In this article, we will be discussing the advantages and disadvantages of both cellulose and fiberglass loose fill insulation so you can make an informed decision that is right for you and your home.

Why You Should Choose Cellulose Loose Fill Insulation?

Different insulation materials work best in different applications around your home, but in terms of the best insulation for loose fill in attics, we believe borate only stabilized cellulose is the way to go. Why? There are a few reasons we recommend this type of insulation. 

  • Cellulose is a plant-based insulator and is the oldest form of home insulation
  • The performance of cellulose loose fill insulation is unmatched – its R-value is significantly higher than loose fiberglass filled insulation
  • Cellulose is eco-friendly – it is made from recycled materials
  • Borates are a highly effective insecticide and pest deterrent
  • Cellulose is less of a safety hazard than fiberglass
  • Dissimilarly to other types of cellulose insulation, borate stabilized cellulose does not contain VOC content and does not release gas like ammonium sulfate stabilized cellulose or formaldehyde containing fiberglass can.

So, with all these benefits, what is the drawback of borate cellulose? It is more expensive than fiberglass insulation.

Why You Should Choose Fiberglass Insulation? 

Some home improvement contractors and industry experts out there might suggest loose fill fiberglass is best because it dominates the new construction housing market. However, the reality is builders these days are under an enormous amount of pressure to deliver the perfect new home, while also cutting costs and staying within budget. That is why many contractors recommend fiberglass insulation. Below are some other points you should know.

  • Fiberglass insulation is cheaper than cellulose loose fill insulation
  • It does not prevent pests and is not an effective insecticide
  • Fiberglass can be a safety hazard – it is a skin and lung irritant 

Perhaps the biggest issue with fiberglass it that it is subject convective air movement, which results in a large decline of its cumulative R-value. This effectively means its insulative value in practical reality can be a lot less than advertised. Not to mention when it is disturbed, fiberglass insulation releases particles into the air, which can easily be inhaled by those near it. 

At Windows on Washington, we have heard from plenty of homeowners who are upset with their attics that contain overblown fiberglass. They report very little change in temperature variation and overall comfort. 

At the end of the day, when a contractor tells you fiberglass insulation is best, what they really mean is its “cheap.” And, WoW believes the decision of which type of insulation to use in your home should not be based on cost alone. In fact, effective insulation can actually save you money in the long run by lowering your utility bills. In our opinion (which is based on science and real world experience), borate only cellulose is the better loose fill insulation. The fact of the matter is, properly installed cellulose insulation can greatly increase the comfort of your home, and lower your energy bills.


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Topics: Summer, Insulation