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.

At the time of this writing, most Colorado counties have adopted the 2018 IECC 0r the 2021 IECC. These energy standards have established that a number of field tests are required to validate the energy performance of a home. This includes blower door testing and duct leakage testing – both are important tests for evaluating residential energy efficiency. In this article, we will take a closer look at duct leakage testing in Colorado.

IECC Duct Leakage Requirements

When it comes to duct leakage testing, the 2018 and 2021 IECC rules are very similar, save for one key difference. In the 2018 IECC, Duct leakage testing is not required on any part of the duct system that is located within the thermal envelope of the building. This rule is consistent with the 2015 IECC. On the other hand, according to section 403.3.6 item #3 of the 2021 IECC, now all ducts must be tested – even if they are within the thermal envelope.

For more information about the 2021 IECC duct leakage code updates, check out our article, Duct Leakage Testing Requirements in 2021 IECC Codes

Testing is required to be performed by an independent third party. The code applies to new home construction and remodels/additions in some municipalities. These rules will vary from county to county, based on what IECC version has been adopted. So its always a good idea to check with the local building department to see what is required.

Purpose of Duct Leakage Testing:

• Studies show that a typical duct installation loses up to 20% of the air before getting to the registers. If that air happens to leak outside the building envelope, the overall comfort of a home can be compromised, and high utility bills will likely ensue.
• When air is blowing through ducts outside the conditioned space of the home, this can cause a change in pressure between the heated and unheated areas. This can lead to more air movement between the two areas which will transfer heat/cool air outside of the home.
• Leaks in ducts can pull in air from these unconditioned areas. High pressure in an attic, for example, can push dirty or dusty air into the home through small gaps in the ceiling.
• Within the home itself, unbalanced air flow caused by duct leakage can pressurize or depressurize zones causing rooms to be stuffy or to have temperature variation.

When is the best time to do a duct leakage test?

Duct leakage testing can be done during various stages of construction and still meet the specifications of the energy code, although we recommend performing it at rough-in when access is easiest. This also gives you the ability to seal sections of the ducts while they are still exposed.

How do we perform the test?

We use the “Duct Blaster” to test the air supply and quantify leakage. We seal off all the registers in the home and run a fan at a return, or at the air handler to depressurize the system. The total amount of leakage in the system is determined by pressurizing or depressurizing the system with the Duct Blaster to 25 pascals.

Click here to view a great article about duct leakage tests from the air leakage pioneers, The Energy Conservatory.

What Comprises a Pass or a Fail?

The threshold for passing the test is determined by a certain number of CFM of leakage per 100 square foot of conditioned space that the system serves. Here are the baseline numbers given in the IECC 2015 codes.

• 3 CFM per 100 SF – Rough-in—with no air handler installed
• 4 CFM per 100 SF – Rough-in—with the air handler installed
• 3 CFM per 100 SF – Post-construction—with no air handler installed
• 4 CFM per 100 Sf – Post-construction—with the air handler installed
• 8 CFM per 100 Sf – Post-construction—with the air handler installed and all ducts within the conditioned envelope (2021 IECC)

Helpful hints to pass your Duct Leakage Test:

• If this is your first test, always have it performed at the rough-in stage so that issues can be easily addressed.
• Liquid Mastic or “pookie” has shown the best results based on our experience.
• Seal every joint. The test is very sensitive, so the HVAC professional may need to seal quite a bit more than normal.
• The furnace or air handler is often overlooked. Seal around the edges and around the back side of the handler where the returns connect.
• Flex duct is popular in attics. However, the zip ties conjoining them to the system have a tendency to leak. Add mastic to these joints as well to create a tight seal.
• Make sure the filter cover is fully installed and sealed before the test.
• Do a once over of the full system before the test to identify weak or unfinished areas.
• It can be helpful for the HVAC installer to be present during the inspection to help identify and repair leaks on the spot.

Scott Home Services

At Scott Energy Services, a division of Scott Home Services, we have a team of highly trained energy efficiency and air leakage specialists. We offer an extensive list energy services including Duct Leakage Testing, Blower Door Testing, HERS Ratings and more! So whatever your building requirements may be, we are here to be of service.

For more information or to schedule a duct leakage test with Team Scott, click here.

If you are in the building industry, you are no doubt familiar with the International Energy Conservation Code (IECC).  This code is used as an industry standard for new building projects and renovations. And it establishes what guidelines need to be followed in order to meet code. As an Energy Services company, we make it our business to stay in-the-know about any IECC updates or changes. That is why we are going discuss the recent changes to duct leakage testing requirements within the IECC 2021 version.

But before we dive into the IECC changes, let’s first discuss duct leakage testing and what it is…

What is Duct Leakage Testing?

Simply put, the purpose of duct testing is to evaluate how well a home’s duct system can hold air. The more leaks your duct system has, the less efficient it will be.

A leaky duct system will result in wasted energy and wasted money. Furthermore, poorly sealed air ducts can cause unevenly distributed heat or AC throughout the home, resulting in an uncomfortable living environment.

At Scott Energy Services, duct leakage testing is one of our primary energy services. Most counties in Colorado adhere to the IECC standards, and thus, the duct leakage protocol. As a result, we have performed hundreds of these tests with our tried and true method!

How Does It Work?

To begin, all duct openings (including supply and return registers) must be sealed off with specialized HVAC tape. A large fan is then sealed securely to the air handler opening or a large return opening (as shown above). However, this is usually done at rough-in on new construction homes.

We run the fan to depressurize the duct system down to -25 pascals. The amount of air moving through the fan is then calculated. This number, referred to as the CFM25, indicates the amount of air leakage in the duct system.

For more details about our duct leakage testing process, you can check out our website.

How Did the IECC 2021 Codes Change Duct Leakage Testing?

Believe it or not, just one sentence was removed from the 2021 IECC duct testing section. However, this one change makes a BIG difference.

If you look at the “exceptions” in the R403.3.3 Duct testing section of the 2018 IECC, it states that “a duct air-leakage test shall not be required where the ducts and air handlers are located entirely within the building thermal envelope.” This is consistent in IECC 2015 codes as well.

The reason this initial exception existed was because if duct leakage occurred within the thermal envelope, heated or cooled air could still be captured to a certain degree.

Now compare that to section R403.3.5 Duct testing in the 2021 IECC, and that statement has been removed. This means that, in jurisdictions that have adopted the 2021 IECC, all air-handling ductwork will need duct testing, even if it does not run outside the thermal envelope of the home. For homes with more than one HVAC system, both systems will need to be tested.

This is big news, and it might be a bit of a curveball for some builders. This is because it has never been a requirement, since the IECC’s inception of the duct testing rule in 2015.

When comparing ductwork that remains within the thermal envelope to ductwork that exits the thermal envelope, leakage requirements differ slightly. According to section R403.3.6, leakage for duct systems that leave the envelope of the home, must not exceed 4.0. cubic feet per minute per 100 square feet of the conditioned floor area. On the contrary, ducts that remain within the thermal envelope must be less than or equal to 8.0 cubic feet per minute per 100 square feet. So there is slight bit more leniency when it comes to ducts within the thermal envelope.

Builders who haven’t needed this type of testing in past projects now must factor it in. They must be sure not to skip over this stage of testing during their projects. It will also contribute to a marginal increase in costs that must be factored where necessary.

What Are the Benefits Of This Change?

This updated code might ruffle some feathers. But from an energy efficiency standpoint, this rule does have its benefits. One of our certified HERS raters, Joe Ophoff, spoke on the matter:

“In new construction home design, there is a great emphasis on air leakage and distribution.  New homes are designed for super performance, so really fine-tuning distribution systems are necessary for comfort throughout the house. Too much duct leakage can indicate a failure in the installation of the duct system, so we can catch a bad install at the ‘rough mechanical’ phase to ensure things are installed correctly. But also, the duct designs are carefully calculated to ensure distribution equilaterally throughout the house, so any significant leakage would affect that.”

Joe illustrates this point well – it all comes down to energy efficiency and optimum HVAC performance. If your interior ducts have too much leakage, they might not evenly distribute heat/air throughout the house. So when you get the system tested during the building process, you are able to pinpoint any issues and have them addressed before the project is finished.

In many counties across the country, including most in Colorado, Manual J/S/D reports are required to get a permit. These reports design the duct system prior to installation; and they calculate the perfect amount and balance of airflow and velocity for each room of the home. However, these reports assume the presence of well-sealed ducts for the results to match the initial calculation.

So this is another step in the process of engineering a super comfortable home for the homeowner, and ensuring everyone is getting the most out of the energy they are using. We wouldn’t be surprised to see actual airflow balancing or velocity testing requirements in the future to even further verify the performance of the duct systems.

In Need of Energy Services?

At Scott Energy Services, a division of Scott Home Services, we are seasoned duct leakage experts. But that’s not all. We also have a number of other energy services, including energy audits, HERS rating, blower door testing, REScheck report services, insulation inspections and air barrier inspections. And we make sure to stay up on the ever-changing codes, in order to help you move along through your project without a hitch.

But what’s a good duct system without the right mechanical design? As you likely know, the IECC requires all new builds and additions to submit a Manual J, S, and D report to ensure mechanical design code compliance. This is another service that we proudly offer. If you need a Manual J/S/D report, we a have team of experts ready to help!

No matter what your next building project needs may be, we would love to be of service! Visit us online to learn more or contact us to book your services today.