Pros And Cons Of Fiberglass Batts

You have a home improvement project that needs to be insulated, and you’re doing your due diligence to research your insulation options. You’ve heard that fiberglass batt insulation is one of the most economic insulations available, but it almost sounds too good to be true. You want to know if fiberglass batts have any issues or drawbacks.

While South Central Services is primarily a spray foam insulation contractor, we install batt insulation for relevant projects. Spray foam is one of the highest-performing insulation options available, but fiberglass batts also have their place in the insulation world.

After reading this article, you’ll have an honest depiction of fiberglass batt insulation. Our goal is to help you determine if this product is appropriate for the project you have in mind.

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Pros Of Fiberglass Batt Insulation

Fiberglass batt insulation is one of the most popular insulation options for a reason. The popularity of batt insulation boils down to three main reasons.

1. Inexpensive
2. DIY capability
3. Sound attenuation

Let’s examine the top three reasons why homeowners often opt for fiberglass.

1. Fiberglass Batts Are Inexpensive.

Fiberglass batt insulation is the most budget-friendly insulation option available. While the cost varies by the batt and its R-value, fiberglass insulation generally costs approximately $1.50 per square foot.

To put that into perspective, closed cell spray foam insulation ranges from $2.70 to $6.00 per square foot for some applications. Open cell spray foam ranges from $1.75 to $3.00 per square foot.

For budget-conscious shoppers, fiberglass batts check the box of being budget-friendly upfront. This low investment cost is likely what drew you to research fiberglass batts in the first place.

2. Fiberglass Batts Have Few Installation Requirements.

If you hire a professional contractor like South Central Services, you can have someone else install your insulation. We do install batt insulation like fiberglass for sound attenuation purposes in interior walls. However, fiberglass batt insulation can also be installed by homeowners.

It is entirely feasible for a homeowner to drop by a Lowe’s or Home Depot to purchase batt insulation that is ready to install. Other insulations, such as injection foam insulation, are only available through certified professionals.

Many homeowners are confident in their DIY skills or looking to save as much money as possible. The ability to install fiberglass batt insulation yourself can be quite appealing.

3. Fiberglass Batts Offer Decent Sound Attenuation.

As a batt insulation, fiberglass does well at absorbing sound waves. Because the batt insulation is neither firm nor solid, sound can become trapped and muffled within the batts. Other insulations, such as closed cell spray foam, do not offer sound benefits.

Cons Of Fiberglass Batt Insulation

Now that we’ve established the benefits of fiberglass batt insulation, let’s examine the drawbacks. While fiberglass batts are inexpensive to purchase and install, you want to know the complete picture of insulating with them. As insulation professionals, we’ve identified four primary problems with fiberglass batts.

1. Poor insulating performance
2. Short lifecycle
3. Limited applications

Let’s examine each of these in more detail.

1. Fiberglass Batts Offer Poor Results Compared To Other Insulation Options.

One of the most significant problems with fiberglass batts is their shape. While the pre-cut and pre-sized rectangles may seem convenient, not every cavity in a home will match these factory presets. If your cavity is larger than your batts, you will create gaps in your insulation. For fiberglass batts to offer their greatest performance, they should fill cavities perfectly with no gaps.

Fiberglass batts are prone to gapping problems. In many homes we’ve insulated, we’ve had to remove ineffective batt insulation before installing spray foam. Any gap in your insulation compromises its performance. Below are some examples of ineffective batt insulation we have removed before installing new insulation.

Whether hiring a professional or completing perfect work yourself, fiberglass batts still risk sagging. Even if the fiberglass batts were installed with no gaps, there is no guarantee that fiberglass will not ever face gap issues. Batt insulation sags over time, creating new gaps and compromising performance.

2. Fiberglass Batts Have A Relatively Short Life Cycle In Real World Applications.

In perfect conditions, fiberglass batt insulation should last for nearly a century. In real-world applications, it may need to be replaced in a fifth of that time. Between gapping, sagging, and potential mold growth, fiberglass batts could show signs of degradation in as few as 15 to 20 years. If installed in a moist environment, batts can degrade in much less time. Fiberglass batts last only a short time compared to spray foam insulation, which is a permanent solution.

Depending on where fiberglass is installed, it could be difficult to check on. A fiberglass batt installed in a wall would be enclosed behind drywall. However, some rooms are also prone to excess moisture. Fiberglass installed in bathroom or kitchen walls is likely to develop mold or mildew and should be checked more frequently.

While fiberglass batts may seem inexpensive up front, costs can add up over time. Insulating with fiberglass means accepting an eventual loss of performance. You may buy new insulation every decade. Or, you may just deal with higher energy bills due to poor performance. Either way, the short life cycle adds up quickly.

3. Fiberglass Batts Have Limited Applications With Reliable Performance.

Fiberglass batt insulation has few applications where it is effective and efficient. We recommend fiberglass insulation for interior walls because any gaps or sagging will not negatively impact overall energy efficiency.

Other places you may consider insulating include your basement, crawl space, exterior walls, and attic. You can install fiberglass batts in exterior walls and attics, but we do not recommend batts for these purposes. Attics and exterior walls contribute massively to overall energy efficiency, and fiberglass batts do not offer enough performance.

As for basements and crawl spaces, fiberglass batts cannot be used because these areas are below-grade. Below-grade applications are moisture-prone. If fiberglass is near moisture, it can develop mold. The only insulation approved for below-grade use is closed cell spray foam.

Fiberglass batts are best used in interior walls where excess moisture is not a concern.

The Bottom Line About Fiberglass Batt Insulation

Fiberglass batt insulation is known for its low investment cost and DIY nature. However, fiberglass is not a high-performing insulation product, and it does not last for a long time. In our experience, in the wrong application, insulating with fiberglass has the same effect as not insulating at all. We recommend fiberglass batts for interior walls that are unlikely to interact with moisture.

For any other home improvement application, there is a better insulation product available. While fiberglass batts are inexpensive, for some applications, they are either not an option or not worth your time or money.

Now that you know the benefits and drawbacks of batt insulation, your next step is to:

• Compare spray foam and fiberglass batts
• Discover if spray foam is a good investment
• Learn how to save on insulation through a tax credit