Proper duct insulation is a major key to ensuring your home’s energy efficiency.

The Department of Energy claims that the average US home loses hundreds of dollars a year in heating and cooling costs. Close to 25% of the energy you use to heat and cool your home disappears through leaky ductwork.

It’s a waste of your money.

The easiest way to reduce this waste – both energy and money- is to invest in duct insulation for your crawlspace.

Keep reading to learn how to save your money by opting for duct insulation.

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What Does it all Mean

Let’s get a couple of definitions out of the way first so that we are all on the same page.

What is Ductwork

Ductwork is the system of ducts and pipes that circulate heated or cooled air throughout your house.

They are the sheet metal or fiberglass conduits you find in your basement and attic.

What is the Crawl Space

A crawl space is usually found under your house. It’s an area of limited height that provides the explicit benefit of allowing you access to your wiring and plumbing.

It is literally a space that you have to crawl into because it is not of walking height.

Some people may use the crawl space for extra storage, but there is limited space. The space is taken up by plumbing, HVAC and electrical wiring.

The Problem with Uninsulated Ductwork

The crawl space is an unconditioned space. This means that, like an attic or unfinished basement, you don’t heat and cool it.

If you have ductwork in your crawl space, the temperature of the duct will be the same as the temperature of the crawl space.

In the winter, a crawl space can be significantly colder than the living spaces of your home. The hot air leaves your furnace at the desired temperature. When it hits the ducts in the crawlspace, that hot air is cooled by the cold ducts. It comes out of the vents at a lower temperature than desired.

This means that your furnace has to work harder to warm up your home. It has to run longer and more frequently because you have losing heat at your crawl space’s ductwork.

On a hot summer day, the opposite would be true. The unconditioned spaces that house your ductwork will likely be hotter than the living spaces. You’ll cool the air in your A/C unit and then warm it back up by sending it through hot ducts.

Leaky ducts also create indoor air quality problems. Drawing crawl space air into the air supplied to the living space can introduce allergens and other air quality issues.

This set up is inefficient, in any weather conditions. It wastes energy and money. Thankfully, efficiency can be easily restored with proper insulation.

Benefits of Duct Insulation

Adding ductwork insulation to your HVAC system provides huge benefits. It lowers utility bills, conserves energy, and prevents condensation issues in the crawlspace.

Overall, you end up with a more comfortable home and wallet.

Energy and Cost Savings

The sheet metal or fiberglass that makes up the ductwork is very thin material. This is why it’s so easy for heat to be lost or gained.

Adding insulation to your ductwork regulates the temperature. It keeps your ducts from being affected by the temperature in the crawl space.

When you aren’t heating the air twice to get your home to the right temperature, you’ll save on your utility bills. You’ll also save on furnace maintenance and repair.

Ductwork insulation means that your furnace doesn’t have to work as hard to achieve the same goal. Reducing the load on the furnace means the equipment will last longer.

Insulation increases the life expectancy of the furnace. You’ll have to repair and replace your furnace less often, saving you tons of money in the long run.

Reducing energy waste also has broader environmental implications. Using energy more efficiently means we have less of a negative impact on the global environment.

Condensation Prevention

Condensation builds up on air conditioning ducts is a common problem when your ducts aren’t insulated.

As the cool air passes through the warm ducts in a warm crawlspace, condensation develops. This condensation can lead to moisture buildup inside your ducts.

In turn, that moisture can lead to negative air quality in your home. Molds and mildews thrive in moist environments.

Insulating your ductwork prevents this condensation in the first place. In the long run, proper insulation will better protect your family’s health.

How to Insulate the Ductwork

There are a couple of steps to insulating ductwork. It is best to work with an HVAC professional who can make sure you are choosing the right insulation and installing it properly.

Determining the Right R-Value

Insulation is rated in terms of its thermal resistance. It gets an assigned R-value, which is a measure of the effectiveness of insulation.  Insulation with a higher R-value is a better insulator.

For your ductwork, you will want to choose an insulation with an R-value of least 5.

Sealing Before You Insulate

Before you insulate the ducts, you need to seal the ducts.

Ducts are inherently leaky at the joints where the pieces attach. It is almost impossible to build leak-proof ducts.

That said, once the ductwork is installed, you can seal the ductwork to reduce leaks. Don’t waste time insulating your ducts if you aren’t also going to be sealing the joints.

Use mastic to seal the ducts. Mastic doesn’t shrink as it ages, so it won’t pull away from the joints. It also doesn’t deteriorate over time. It will last the lifetime of your HVAC system.

Despite the name, don’t use duct tape to seal your ducts. It is sticky, ineffective, and breaks down over time.

Once you seal your ducts, you can insulate the ducts.

Choosing the Type of Duct Insulation

There is more than one way to insulate ductwork. The insulation type will be determined by your ductwork configuration and budget.

The two most common ways to insulate ductwork are

  • Wrapping the duct in a foil-faced blanket; or
  • Applying spray foam insulation to the outside of the duct.

If you need help deciding which type of insulation you need, set up an energy consultation.

Start Saving Money Today

Stop wasting money and energy with a leaking duct system. You’re throwing money out the window.

Invest in duct insulation today to safeguard your family’s health and your pocketbook.

To learn more tips and advice on duct insulation and other homeowner topics, check out our blog.

Contact Crawl Pros today for an estimate on upgrading your duct insulation.


Our professional estimators can see you in as little as a day.


Give us a call today at 866-673-9626

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