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Fiberglass Insulation Batts: Why the Popular Choice May Not Be the Best Choice

There are some solutions to the fiberglass batt problem. All of them lie in a different type of insulation. Injection/spray foam addresses all of the concerns and provides an air seal that eliminates unwanted airflow, and lasts the lifetime of your home.
Fiberglass Insulation

Imagine this scenario. It’s 5 pm. You have just finished work, and you are certain of two things. The first is that you are beyond starving, and the second is that you are exhausted from a hard day at the office. You need dinner for yourself and there are a couple of options. You can either go through the local drive-through or go home and make dinner. Fast food offers convenience without breaking the bank, and everybody else is doing it. However, making a habit of this choice can cause health problems and added expenses down the road.

You can compare this scenario to your home’s insulation. While the products are different, a parallel can be drawn when you think of your home’s insulation as the food you eat and your home as your body. Fiberglass batting is the most commonly used type of home insulation, but is it the most effective? And, does it make the most sense in the long run? Fiberglass became popular at a time when parts of a house were just thought to be parts of a house. Yet as technology has progressed, building scientists have realized that each part of a house actually works together as a whole system.

Three-quarters of residential buildings are insulated with fiberglass batts and a staggering 70% of energy in residential buildings is spent on heating and cooling. Which, makes you wonder, “Is the insulation really doing its job?” Like your eating choices, your insulation choices can have actual health and financial implications for years to come.

Why People Choose Fiberglass Batts

The most commonly used insulation in residential buildings is fiberglass batts. So there must be some redeeming qualities that make them popular, and indeed there are. The first reason and probably the most popular reason that fiberglass batts are used is that they are relatively inexpensive when compared to the other types of insulation available. They are also widely available and easy to install. Fiberglass batts are good thermal insulators, and the fiberglass itself doesn’t burn.

So What’s the Problem With Fiberglass Insulation?

Remember how I mentioned earlier that all the parts of a house work as a system? Fiberglass batts do not do a good job working as part of the home system. The biggest problem with fiberglass batts is airflow. Unwanted airflow can negatively affect your ability to keep a constant temperature in your home, air quality, and unwanted moisture. The air we breathe contains more than just oxygen. Here are a few ways unregulated airflow can negatively affect your home.

Moisture Control
  • Air contains a small amount of moisture. Hot air can hold more moisture than cool air. Heat flow is always from hottest to coldest. As warm air flows to cooler air, its moisture-holding capacity decreases and releases excess moisture. This is how condensation happens. Air deposits moisture into your insulation when it flows freely through the floor, walls, and roof of your home.
Air Quality
  • When moisture deposits in fiberglass batts, it becomes a breeding ground for mold and mildew. Air passes through your building structure; it brings in allergens from the outside and any “fun things” growing in your insulation. Tiny furry friends also love to make homes in fiberglass. I don’t even want to think about the fun things that live, crawl, and even die under a house. With uncontrolled airflow, all those things affect the air quality in your home.
Heat Flow
  • Heat will always travel from warmer areas to cooler areas. This means that the air in your home is trying to escape the cold outside world during the winter. In the summer, the hot, muggy air will launch an attack on all the air you are paying to cool off. If the insulation allows for airflow, you can guarantee that you will be paying more than you need to every month to keep your home warm or cool, depending on the season.

So while a fiberglass batt boasts a high r-value (determined in a lab in optimal and unrealistic circumstances), it can only maintain that r-value if cut and installed correctly. The effectiveness of insulation depends upon the accuracy of the installation process. Batts cut to fit into a wall cavity, even if a millimeter too short, can allow a significant amount of airflow. Cut too long and shoved into a wall cavity or shoved around wiring and pipes, the batt loses a substantial amount of its stated R-values. If framing isn’t exact and the batts don’t fit perfectly, gaps and compressed fiberglass may lead to less than optimal performance. Not to mention, as fiberglass batts age and start to sag, the r-value drops, and the gaps for airflow increase and the replacement of fiberglass is necessary.

The Solution to the Problem

There are some solutions to the fiberglass batt problem. All of them lie in a different type of insulation. Cellulose or blown-in fiberglass insulations can solve some of the issues. For optimal performance, you should consider RetroFoam injection foam (or spray foam for new builds, attics, and crawl spaces). Injection/spray foam addresses all of the concerns listed above, can provide an air seal that eliminates unwanted airflow, and lasts the lifetime of your home.

Contact one of our representatives to answer your questions or find out how to get a free estimate for your home.


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