Heating & Cooling

Pleated Filters or Fiberglass Filters: Which is Better?

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Pleated and fiberglass air filters are the two most common options for in-home HVAC systems. They’re practical, affordable, and efficient. Some people prefer fiberglass filters because of their low cost. Others like the pleated filters because they can capture microscopic allergens from the air.

Pleated air filters provide better air filtration than fiberglass air filters. Pleated air filters are available in various MERV ratings from 5 to 13. Pleated air filters have more surface area allowing them to capture more airborne pollutants and allergens such as pollen, pet dander, and mold spores. Pleated filters are stronger and can last up to 90 days, three times longer than fiberglass filters.

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Fiberglass air filters are not as strong as pleated filters. The cardboard frames in fiberglass filters bend easily, which can cause the filter to collapse onto itself. Fiberglass filters also provide little protection against small airborne particles. The material is not tightly woven, which can’t capture microscopic particles. Fiberglass filters need to be replaced every 30 days.

Throughout this article, you’ll learn all sorts of helpful information, including:

  • Why are pleated filters so much better than fiberglass filters
  • Which MERV ratings should you choose
  • Whether or not pleated filters restrict airflow

Why Are Air Filters Pleated?

Pleated air filters are folded into an accordion fashion to allow for increased surface area to capture more airborne particles. The pleated design doubles the surface area of traditional fiberglass non-pleated air filters.

The pleated design improves airflow as the creases’ ridges help distribute air more evenly than non-pleated filters. Increased airflow means your HVAC system doesn’t have to work as hard, thus increasing longevity.

Do Pleated Air Filters Restrict Airflow?

Pleated air filters are much more sought-after because they catch far more pollutants. Various particles floating through the air are caught in the weave of a pleated filter that would pass right through ordinary fiberglass air filters. The downside to this efficiency is that it can quickly lead to restricted airflow.

When the airflow is reduced, your energy bill climbs up, and dust eventually causes a severe blockage, starving your system of necessary airflow. The proper air filter maintenance will keep your airflow as it should be without risking damage to the internal coils.

If the internal coils get dirty, that dirt mixes with the condensation produced, forming a slug that can clog your condensate drain pipe. A clogged drain pipe can cause major problems to your heating and cooling systems and interior water damage.

Pleated air filters can reduce or even eliminate the need to have your air ducts cleaned. Our article Should You Clean Your Air Ducts? Separating Fact and Fiction provides information on cleaning air ducts and how to prevent the need from arising at all.

  • Clean and replace your air filter regularly. Most are pleated, and fiberglass air filters are disposable. It would be best if you replaced fiberglass air filters every 30 days. US Home Filter states that you should replace pleated air filters once every 90 days to prevent the dust from building up. However, your pleated filters may need to be changed sooner if you have several in-home fur babies.
  • Choose the correct MERV rating. A MERV rating is a system based on the efficiency of a filter. The higher the number, the denser it is. High-density MERV filters catch tons of dust but can get clogged more quickly. In the next section, you’ll be able to figure out which MERV rating is meant for your home.
  • Get the right size filter. Aside from the rating above, it would be best to have the correct dimensions of a pleated filter. Anything too big will become bent, limiting the effectiveness of the filter. On the other hand, a too-small filter will allow dust particles to pass around the filter without resistance.
  • Don’t clean disposable filters. Some homeowners get too tempted to reuse their air filters by cleaning them with bleach and other chemicals to wash the debris away. Unfortunately, this will damage the fibers and weaken the cardboard frame, making them likely to rip the filter apart. Reusing cleaned air filters can cause the fibers to get clumped, cause dust to build up, and restrict the airflow much quicker.
  • Inspect the pleated filter after a windy day or a storm. When wind moves particles through the air, your filter is forced to work extra hard. Sand, dust, dirt, and other debris can clog your filter quickly. You might not have to replace it, but giving it a shake-off will keep it going as it should.

What MERV Rating Should I Buy?

As you probably read above, the MERV rating of your filter will determine how well it works. Hospitals and nuclear power plants have incredibly high MERV ratings, reaching upwards of 15 to 20. These ratings would be virtually useless in your home. They’d be worse than having no filter at all.

It’s important to remember that there’s a limit to MERV ratings before air can’t flow through it properly. In-home pleated air filters should have a rating between 5 to 13. Aim for the scale’s higher end if you live in a windy region with lots of dirt and dust. If you’re fortunate enough to have low humidity, low wind, and not too many pollutants, 5 to 8 will work fine.

SecondNature.com shows us that the incorrect MERV rating can harm our air circulation systems. A filter that is too compact and dense prevents air from flowing through regularly. For example, getting a pleated filter with a MERV rating of 18 would stop potential viruses from flowing through, much less dust and other debris.

The goal is to have dust trapped, but dust will clog the filter in minutes when it gets too high. Since you’re trying to stretch it up to 3 to 6 months at a time, you can see how the expenses can add up quickly.

On the flip side, low MERV ratings become ineffective. When dust can flow freely, having a filter is almost pointless. Anything below a five won’t be helpful enough to purchase.

You’d think companies would only produce air filters with the necessary MERV ratings, but you’d be wrong. Many brands try to push low-cost filters without labeling a MERV rating. You’ll get a great price with a filter that’s barely efficient enough to sort out coffee grounds, much less dust.

Why Are Pleated Filters Better Than Fiberglass?

As mentioned in the introduction, pleated filters are much better than fiberglass filters. If you’re still on the fence between the two options, let’s examine five reasons that this statement holds:

  1. Pleated filters last much longer than fiberglass filters. They’re built to hold together for extended periods, overshadowing the value and efficiency of any fiberglass filter on the market. Not only that, but they can withstand more dust and other particles before needing to be replaced.
  2. Pleated filters are made with higher quality standards than fiberglass filters. Most fiberglass filters are good enough for houses, but they’re some of the lowest quality filters. Pleated filters have densely woven fabric that doesn’t loosen from excess pressure or airflow.
  3. Another reason you might want to choose pleated air filters is because they come in various MERV ratings. Rather than being stuck with unmarked or low-rated fiberglass filters, you can choose anything between 5 to 13 on the scale. Note that most pleated air filters have a MERV rating of 8.
  4. Fiberglass is messy to deal with and itchy on the skin. If you’ve ever worked with fiberglass, you know how bad it can be when it starts to get on your arms and face. You’ll need to wear protective clothing when you’re cleaning or replacing the filter. There’s also a small risk of sending fiberglass throughout your home.
  5. Finally, many houses and apartments require pleated filters. You don’t even have the option to choose fiberglass, making it not worth buying in the first place. The benefits above favor pleated air filters, so most landlords refuse to use fiberglass.

The pros of pleated filters far outweigh the cons. As long as you clean and replace them on schedule (see manufacturer recommendations), you shouldn’t have a problem with restricted airflow.

Pleated air filters are designed to be installed in the airflow direction. Improper installation can restrict airflow and cause the filter to fail prematurely. See What Happens If My Return Air Filter Is Installed Wrong for more details and determine if your air filter is installed correctly.

To the same point, running your heating and cooling system without an air filter can damage the internal coils.


Pleated filters are better than fiberglass air filters, without a doubt. Perhaps the best news is that you don’t have to spend too much money on them than you would on a fiberglass filter. They also last much longer, so you’ll save your hard-earned money in the long run.

Here are what you should have learned from this post:

  • Choose a MERV rating between 5 to 13.
  • Pleated filters are much more efficient than fiberglass filters.
  • Fiberglass can be ineffective and potentially dangerous.
  • If they’re not cleaned or replaced, pleated air filters can restrict airflow in your home.
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Hubert Miles | Licensed Home Inspector, CMI, CPI

Hubert Miles is a licensed home inspector (RBI# 2556) with more than two decades of experience in inspection and construction. Since 2008, he has been serving South Carolina through his company, Patriot Home Inspections LLC. As a Certified Master Inspector, Hubert is dedicated to providing his expertise in home inspections, repairs, maintenance, and DIY projects.