Are You Inhaling Fiberglass?

Worker Holding a Fiberglass Insulation Batt

We definitely hope you aren't inhaling fiberglass particles, but you could be.

When we perform home performance services, we often encounter indoor air quality issues that our clients weren't aware of. One of those is the presence of fine airborne fiberglass particles that enter their living spaces. Unfortunately, it's really really easy for this to happen.

Let's take a look at some of the ways fiberglass might weasel its way into your home's airstream. We'll also look at how to address the problem and avoid it in the future.

How airborne fiberglass gets into your home

Fiberglass isn't the worst thing you could be inhaling, but it's certainly not benign. According to multiple states' health departments, inhaling fiberglass can cause coughing, wheezing, and itching. The fibers can also exacerbate existing bronchitis or asthma, cause a sore nose or throat, and irritate the eyes.

These are the same little glass particles that dig into your skin and make you itch when you're handling insulation. You don't want them in your lungs.

Leaky HVAC air return

One way fiberglass enters your airstream is via a leaky return air duct in your attic.

The return side of your HVAC system is where air is pulled into the air handler to either be heated or cooled. If the return duct has gaps, cracks, or holes in it and it's passing by a bunch of attic insulation, it's easy to see how the blower fan could pull little bits of the loose fill or batt fibers into the system.

After passing through the air handler, the fibers then enter your HVAC system's supply ducts. These are the ones that blow conditioned air into your house.

Basically leaky return ducts = potential for fiberglass in your airstream.

Ductboard plenums and fiberglass duct boots

If your duct system uses ductboard for the return plenum, you could be breathing fiberglass.

That's because ductboard is made from fiberglass. As the ductboard ages and any seals begin to deteriorate, raw fibers become exposed and can easily be sucked into the HVAC system on the return side.

The same is true for fiberglass duct boots. In many homes, the return duct boots are made from fiberglass. Like the ductboard plenums, these can deteriorate with age and the fibers can loosen inside of them.

Fiberglass-lined furnace

Some furnaces are lined with fiberglass material on the inside. Much like ductboard plenums, the inside of these units can deteriorate with age. As the fiberglass interior withers, your blower fan can pull the fibers into your airstream.

Not all furnaces are lined with fiberglass, but some are. On its own, a fiberglass lined furnace is fine. It only poses an indoor air quality problem when the fibers dislodge.

Ridding your home's airstream of fiberglass

Now that you know the potential sources of your airborne fiberglass problem, here are some different ways to address them.

1. Blower door test

Have a home performance professional perform a blower door test. During this test, the contractor pressurizes your home and uses an infrared camera to identify all the areas where heat is moving. This helps us identify the exact areas in your return duct where the blower fan is pulling in attic air.

After figuring out where the fiberglass is getting in, we can seal the leaks and prevent additional particulates from passing into the duct.

2. Replace ductboard plenums and fiberglass duct boots

Metal plenums and duct boots are the way to go. They're more durable, less prone to damage, and don't contain any fiberglass. You'll need to insulate the new ducts from the outside, but after that, they perform fantastically.

3. Line your furnace with bubble wrap insulation

If your furnace's blower compartment has a compromised fiberglass interior, you need to cover it up. Bubble wrap insulation is the way to go here.

This is the reflective, silver stuff. Have an HVAC pro line the inside of your furnace with it so that none of the fiberglass particles can dislodge.

4. Clean your ducts

After ridding your airstream of future contaminants, it's time for a deep cleaning. Duct cleaning ensures there aren't any lingering fiberglass particles or other nasties inside your ducts that can enter your airstream.

A healthy duct system means healthy air

Fiberglass isn't the only potential contaminant that can enter your home through your ducts. In homes where the HVAC system's indoor unit is in the crawlspace, a well-sealed return duct also ensures molds and soil gasses have a harder time getting into your house.

Many houses have leaky return and supply ducts. In both cases, the leaky ducts cost you money. On the supply side, a leaky duct prevents conditioned air from getting to where it needs to go. On the return side, leaky ducts mix too-hot or too-cold air with your conditioned air and force the HVAC system to work harder. Leaky return ducts, as we've just seen, can also create indoor air quality hazards.

For these reasons, having a healthy duct system (i.e. well sealed and insulated with no obstructions) is essential! The best way to get there is via a home assessment that includes a blower door test.

That way, we can find out for sure whether you have leaky ducts and where the leaks are. Afterward, we can get to work minimizing your duct leakage.

The way we see it, you deserve to breathe healthy air. No fiberglass. No contaminants.