When Is Duct Leakage Testing Required In Colorado?

You may have heard of a duct leakage test in Colorado, and you might be wondering if it is required for your new home. In this article, we’ll discuss the test, when it is required, how it is performed, and what you’ll need to do to pass. Let’s get started.

Understanding When Duct Leakage Testing is Required In Colorado

Duct leakage testing was first required by the 2015 IECC building code. This means that any Colorado counties or cities that have adopted the 2015 IECC (or any subsequent iterations of the code) are required to perform duct leakage testing on all new homes or additions with duct systems. According to the 2015 IECC and 2018 IECC, duct leakage testing is only required on ducts that are located in areas outside of the conditioned space, such as:

• An attic
• An uninsulated crawl space
• A garage
• An exterior utility room
• A garage attic

Essentially, if any piece of the system is outside the heated space, you will need to perform the test. Even if there is just one flex line going through an attic, or an unconditioned crawl.

The 2021 IECC duct leakage testing rules are similar to the 2018 and 2015 IECC, except for one very significant difference.

If you look at the “exceptions” in the R403.3.3 Duct testing section of the 2018 IECC, it states: “a duct air-leakage test shall not be required where the ducts and air handlers are located entirely within the building thermal envelope.”

But if you compare that to the R403.3.5 Duct testing section in the 2021 IECC, the above mentioned “exception” has been removed all together. This means that, under the 2021 IECC building code, all air-handling ductwork will need duct testing, even if it does not run outside the thermal envelope of the home. 

Need a duct leakage test performed? Learn more and schedule one today!

How Is The Test Performed?

Using a special fan, air is pumped through your ducts at a specified pressure of 25 Pascals, equivalent to 0.1 inch w.g. (Water Gauge). All of your registers will be sealed during the test. The sealing is performed with special HVAC tape, but many times HVAC contractors will seal the ducts during construction as well. Learn about the best ways to prep for the test here.

By measuring the fan output and the amount of additional air pressure required to maintain the proper pressure in the ducts, the total amount of leakage in your duct work can be measured. When a duct leakage test is required in Colorado, these are the necessary steps taken.

What Counts As A “Pass?”

To pass the test, your home must meet the following test results. Note that numbers 1 and 2 are required by the 2015, 2018 and 2021 IECCs. Whereas, number 3 is only required by 2021 IECC.

1. Rough-in test – If the air handler has been installed, leakage must be less than or equal to 4 cubic feet per minute, per 100 square feet of conditioned floor area. If the air handler is not installed at the time of the test, leakage must be less than or equal to 3 cubic feet per minute, per 100 square feet of conditioned floor area.
2. Post-construction test – Total duct leakage must be less than or equal to 4 cubic feet per minute, per 100 square feet of conditioned floor area. In addition, building framing cavities cannot be used as ducts or plenums, and any mechanical piping carrying fluids over 105 degrees Fahrenheit, or under 55 degrees Fahrenheit, must have a minimum insulation level of R-3.
3. *Additional Rule for 2021 IECC* Test for ducts within thermal envelope: Where all ducts and air handlers are located entirely within the building thermal envelope, total leakage shall be less than or equal to 8.0 cubic feet per minute, per 100 square feet of conditioned floor area.

If you do not pass, your ducts may need to be reworked, or sealed, to reduce air leakage and ensure compliance with the building code in your jurisdiction. In many cases, installing AeroSeal can help seal the system, if the ducts have difficulty passing the test.

For more info about the 2021 IECC Duct Leakage Testing update, check out this article.

Know The Basics About Duct Leakage Testing – And If It’s Required For Your Home!

A properly-built new home will have no issues passing IECC duct leakage standards. So make sure you know what to expect from your duct leakage test, and prepare accordingly – you’re sure to pass with flying colors. We can help with fast scheduling and experienced technicians when you order a duct leakage test through Scott Home Services.