When the 2015 International Energy Conservation Code (IECC) went into effect, blower door testing became a requirement on all new residential builds and remodels. Prior to this code update, blower door testing had been in use for many years. However, this was the first time that it had become mandatory for many new construction projects.

The International Code Council (ICC) saw it fit to address the issues that can occur with too much air leakage in homes. Therefore, this rule was established as a way to increase energy efficiency in new residential builds.

Counties that have adopted the 2015 IECC (or any later edition) require that any new build must have a blower door test performed by a licensed, third-party company. The results of the test must not exceed the region’s maximum leakage rate in order for the building to be deemed IECC-compliant. It is a crucial aspect of the modern building process in the majority of the nation. So what is blower door testing?

What is blower door testing?

A blower door test is a procedure that involves using specialized equipment to measure the exact air tightness of a home. Depending on the region of the country, a maximum air leakage rate is defined, and each new home must meet this air tightness level.

This technique is the industry standard and is extremely accurate. Furthermore, it not only helps to determine the level of air leakage, it can actually help you to determine the exact sources causing the air leaks.

How does it work?

A blower door consists of a frame and flexible panel that fit into an exterior doorway. A powerful, variable-speed fan mounts into the frame.

All exterior openings – such as doors, windows, flues vents etc. – are closed off or sealed. The fan is then activated to blow air out of the house, lowering the inside air pressure. The higher outside air pressure then flows in through any unsealed cracks or openings.

As the fan runs, an integrated pressure gauge measures the pressure differences between the inside and outside of the home, and an airflow manometer and hoses are utilized for measuring airflow.

The equipment used in the blower door test determines a home’s air infiltration rate, which is measured in air changes per hour (ACH). This is the number that is required by the IECC code. For most Colorado municipalities, the air leakage rate for new residential builds or remodels must not exceed 3.0 ACH.

As the blower door fan runs, the technician is able to walk the house, searching for sources of large leaks. Having conducted thousands of tests, our experts know where to look for primary problem areas. Furthermore, we utilize infrared scanning devices to help detect temperature differentials within the home –  a sign that could indicate air leakage.

A specialist can then help to pinpoint the issues, when present, and relay this info to the project contractor in a timely manner. Find out more about common leaks found during a blower door test here.

Do you need a blower door test performed on your project fast? We can help! Visit our blower door service page to learn more and schedule now.

When do you perform a blower door test?

According to the IECC, the test should “be performed any time after creation of all penetrations of the building envelope have been sealed.” Basically, the home should be as close to being complete as possible, with exterior penetrations sealed properly and all the drywall completely installed, before carrying out the a blower door test.

Any leaks caused by an incomplete building envelope could potentially affect the test results. That’s why the full building envelope needs to be sealed before an accurate test can be conducted.

Who can do the testing?

Here at Scott Energy Services, a division of Scott Home Services, LLC, we proudly offer blower door testing services to the Colorado Front Range. We also offer an extensive list of other energy services including duct leakage testing, insulation inspections, air barrier inspections, full energy audits, Manual J,S &D report preparation, as well as full energy rating services including RES-Check reports and HERS ratings. Check out a full list of our services here.

Is this required in the county you are building in?

Most of the counties along the Front Range of Colorado have moved to at least the 2015 IECC building code by this time. However, we encourage you contact your municipality in order to confirm which code guidelines your building project must adhere to.

If you are a contractor, builder or architect in Larimer County, CO, you are probably aware that the area has adopted the 2021 International Residential Code (IRC). This is a series of rules established by the International Code Council (ICC) to which all new residential building projects must adhere.

As of March 2022, several amendments were added to the overall IRC. And Larimer County has opted to adopt these amendments, as well. One of the big changes is that air barrier inspections are now required on new builds.

Building Envelope Performance Verification

The state of Colorado is constantly striving to increase statewide sustainability. That is why factoring in energy efficiency is a major part of the CO residential building process. It is no surprise then that many counties, including the Larimer County, have adopted the energy-related guidelines of the IRC. Chapter 11 of the IRC focuses on energy efficiency.

One of the primary amendments to this chapter now requires “building envelope performance verification.” This means that, before siding is added to a home, a certified inspector must examine and approve its exterior air barrier. Additionally, an air leakage test must be conducted on the home upon completion to make sure it meets energy efficiency requirements. The excerpt below highlights the key points in the amendment:

1. A review of the construction documents and other supporting data shall be conducted to assess compliance with the requirements in this section.

2. Inspection of continuous air barrier components and assemblies shall be conducted during construction while the air barrier is still accessible for inspection and repair to verify compliance with the requirements of this section and Table N1102.4.1.1.

3. An air barrier and air sealing inspection report shall be provided for inspections completed by the approved air leakage testing agency. The air barrier and air sealing inspection report shall be provided to the building owner or owner’s authorized agent and the code official at the time of the framing or insulation inspection. The report shall identify deficiencies found during the review of the construction documents and inspection and details of corrective measures taken.

As stated in the excerpt above, the construction docs will be reviewed by a qualified inspector. These building plans should meet the guidelines established in  the amended rules. Furthermore, the actual construction should follow the construction plans.

It is key to conduct the exterior inspection while the barrier can still be accessed. That way, if any deficiencies are noted, they can be adjusted or repaired efficiently. It would be a much more difficult task to make any air barrier changes after the exterior siding is installed!

A guide in the IRC (labeled as Table N1102.4.1.1) provides an in-depth breakdown of all components of the home, and how each of them should be configured in order to meet code requirements.

Meeting Air Barrier Code Requirements

When it comes to this code, the overall concept is simple – a continuous thermal envelope. or air barrier must be constructed around the house. Any breaks or joints in the air barrier material must be sealed by a code-approved material. Also, the insulation material used for the air barrier cannot be air permeable.

As mentioned above,  Table N1102.4.1.1 provides an extensive explanation regarding each component of the house. So if you want the nitty gritty details, go take a look a the table. But for the sake of this article, we will give you a brief overview:

• Ceilings/Attics – Inspectors will want any access points to unconditioned attics to be sealed with the proper air barrier materials. Additionally, any dropped ceilings or soffits should be outfitted with an air barrier that is aligned with the insulation.
• Walls – Any junctions from sill plate to foundation or top plate to exterior walls must be properly sealed. Additionally, if your attic has knee walls, they must be sealed.
• Windows/Skylights/Doors – All the framing of these penetrations needs to be properly sealed.
• Rim Joists – Exterior air barriers must extend over any rim joists.
• Floors – Any exposed edges of floor insulation must be reinforced by an air barrier. This also applies to cantilevered floors and floors above garages.
• Basements/Crawl Spaces/Slab Foundations – Exposed earth in unvented crawl spaces must be covered with the proper air or vapor barrier. Penetrations in foundation walls and slabs need to be sealed properly.
• Shafts/Penetrations – Ducts, shafts, or penetrations to the exterior or unconditioned spaces must be sealed with approved materials.
• Narrow Cavities – Any cavities too narrow to hold insulation need to be air sealed.
• Garage – Air sealing is needed between the garage and conditioned spaces.
• Recessed Lighting – Lighting fixtures present within the thermal envelope of the building must be properly air sealed.
• Wiring/Plumbing/Other Obstructions – Any breaks in the thermal envelope caused by wiring, plumbing etc. need to be sealed.
• Showers/Tubs – The air barrier installed adjacent to tubs or showers must separate the exterior wall from the tub/shower.
• Electrical or Phone Boxes – Air barriers must be installed under exterior electrical or phone boxes. Air sealed boxes can also be installed as an alternative.
• HVAC Register Boots – HVAC supply/return register boots that penetrate the thermal envelope need to be air sealed.
• Concealed Sprinklers – Concealed fire sprinklers must be sealed, where necessary, according to manufacturer’s recommended method.

Air Barrier Inspections

At Scott Home Inspection, we offer all the Energy Services you’ll need to make sure your building project is up to code. As a qualified third party inspection firm in Larimer County, we have a team of specialists that can inspect and document the exterior of the house to ensure that the building envelope is sufficiently configured.

Additionally, we are also certified to perform blower door, air leakage testing in Larimer County. Due to its adoption of the IECC Residential Energy Codes, Larimer County has required this type of testing in new builds for several years.

By conducting blower door tests, our energy specialists are able to not only determine the energy efficiency of the home, but also identify the sources of air leakage. That way you can make the necessary repairs, as needed, and continue to progress through your building process without a hitch.

We are proud to offer a whole list of specialized Energy Services to Larimer County. We have been providing the region with some of our milestone services such as blower door tests, insulation inspection, and duct leakage testing for years. And now we are ready to take on the newly mandated air barrier inspections with the same professionalism, expertise and efficiency.

If you are in need of an air barrier inspection (or any inspection service for that matter) for your building project, please don’t hesitate to reach out to Scott Home Inspection today! Click here for more info, or click here to schedule your service.

As modern day homeowners, we face so many month-to-month expenses. There are routine maintenance expenses, repairs, utility bills, insurance, mortgage payments and the list goes on. With all these recurring expenses hanging over our heads, there is one thing we all have in common – we want to save money. So how do we do that?

You can, of course, cancel that gym membership, discontinue that Hulu subscription, decrease your daily visits to Starbucks, etc. But how many of us focus on the energy efficiency of our own homes? Air leakage in the home can be a prime source of wasteful energy use and high energy bills.

A bit more knowledge about this topic can go quite a long way. In addition to saving money, decreasing air leakage can also make your living space a much more comfortable and healthy environment.

What Is Air Leakage?

Air leakage occurs when outside air enters the home and conditioned air exits the home in an uncontrollable manner through cracks and openings. When air leakage occurs in excess, it can drastically affect energy efficiency. Furthermore, with air freely transmitting in and out of the home, occupants will have a harder time creating an optimum living space.

Over the years, building methods have advanced to really improve energy efficiency. Various insulation products, house wraps, and building techniques have helped to increase the overall “air tightness” of new builds. It is always recommended to address air leakage throughout the building process, so as to avoid energy efficiency issues down the road.

It is definitely more common for old homes to be drafty, because they were purposely built to have more breathability. But even newer builds can have air leakage issues.

There are a number of common points where air leakage can take place in the home. Windows, doors, recessed lighting fixtures, exterior wall penetrations, ducts, fireplace walls are a few examples of trouble areas (see more examples in the image below).

Some of these trouble areas can be discovered simply through visual inspection. For instance, if you see a large gap between your front door and door frame, there are obviously air leakage issues at that location. And you will want to remedy the defect with the appropriate weather stripping.

However, some of these problematic areas are not so easy to identify with the naked eye. In these cases, you should hire a specialist who can evaluate your home’s energy efficiency with a blower door test.

The Pros and Cons of Low Air Leakage

As we’ve already discussed, reducing air leakage in your home will save you money. During the hot months of the year, a home with bad air leakage means hot air coming into the home, and cool, conditioned air leaving the home.

In this scenario, your AC system will work hard to maintain your ideal temperature, resulting in unnecessarily high electricity bills. And the same (vice versa) thing will happen during cold months – cold air gets in, heated air escapes. This results in a cycle of  year-round energy inefficiency.

On the contrary, an air tight home would improve energy efficiency and help you to save your hard earned cash!

Low air leakage also means a more comfortable, climate-controlled and healthy in-home environment. You will have less fluctuations in your indoor temperature. So when it comes to your thermostat, you can set it and forget it.

Air leakage can allow humid and moist air to enter the home. This can obviously result in an uncomfortable living environment.

But in even worse case scenarios, excessive moisture in the home can lead to chronic mold issues, which can affect occupant health. And if the moisture intrusion is consistent and severe enough, it can lead to interior damage, which may necessitate costly repairs.

The main con of an airtight home is that it creates a potential decrease in overall natural ventilation. Without a natural source of ventilation, airborne particles such as dust, mold spores, germs, and even exhaled carbon dioxide may remain trapped inside the home, creating poor quality air.

This a legitimate concern. We, of course, want to optimize our energy efficiency. But we also don’t want to compromise our access to fresh, healthy air.

Well, this issue has been appropriately addressed by a simple concept: “Build Tight, Ventilate Right.”

When it comes to airtight homes, proper ventilation is key. And two main types of systems are utilized to achieve proper ventilation – Heat Recovery Ventilators (HRV) and Energy Recovery Ventilators (ERV). These systems create a cyclical exchange within the house, which pulls in fresh air from the outside, while expelling stale air to the exterior.

How Do I Know If My Home Has Air Leakage?

Your house likely has air leakage, because pretty much all homes have some degree of air leakage. The real question is how much air leakage does your house have? As we mentioned briefly above, the industry standard for measuring air leakage is a blower door test.

During these tests, a specialized device (shown below) creates a suction to depressurize the home. This depressurized environment allows the blower door technician to measure how much air leakage is occurring in the home, and whether or not further action is needed.

If you are a homeowner in Colorado, we offer a blower door test with our comprehensive Energy Audit. Our energy specialists will evaluate air leakage, but also analyze insulation levels, windows and doors, mechanical devices, and more. An energy audit gives you a full picture of possible upgrades to lower your energy bills.

Most Colorado counties are now requiring newly constructed homes to meet a number of energy efficiency criteria established under the International Energy Conservation Code (IECC). This code’s primary goal is to increase sustainability and to regulate energy consumption.

The code makes blower door testing a mandatory step for many construction projects to ensure optimum energy efficiency. Depending on where you live, the rules of the IECC may even apply to you.

But regardless of rules and regulations, assessing the air leakage of your own home is never a bad idea. Because who doesn’t want to optimize their living space and save some cash while doing so?

If you are curious about the energy efficiency of your home or construction project, feel free to reach out and schedule a blower door test today.

Now that blower door testing is in full swing in Denver, we’d thought we would write a blog about the different requirements the city has to help clear up common questions our clients have.

The requirements vary from new homes to additions, and Denver’s requirements are slightly different than other counties in Colorado.

While it would be ideal to have a statewide-adopted energy code baseline, that is currently not the case. Each county has adopted a different version of the IECC energy codes, and each one has its own amendments as well.

Not to fear because as energy service providers, we do our best to keep up with the changing energy codes throughout our service areas and pass that info along to our partners.

So let’s dig in! But first….

What is a blower door test?

As a brief refresher, a blower door test is an air leakage test that measures how well sealed the home’s envelope is. This is done by running a sealed fan through a doorway and measuring the amount of air moving through a fan at specific pressures. If you want to learn more about the actual process, read our overview here.

As the HVAC system produces hotter or colder temperatures within a home, the air will want to neutralize itself by moving out of the home’s envelope. If the air leakage in a home is higher, this will cause the HVAC system to run more often as conditioned air escapes.

Although the test itself has its limitations, a blower door test is a great baseline that gives us the ability to compare homes to one another.

Most importantly, a blower door test is required during the building process by most counties in Colorado. This is something you should be aware of throughout the building process as some of the largest air leaks can only be sealed prior to drywalling or insulation.

If you are in need of a blower door test anywhere from Fort Collins to Castlerock including Denver, visit our Blower Door Testing page for more info or contact us now!

Denver Blower Door Requirements on New Construction

Denver has unique air leakage requirements, but they are pretty straightforward. New construction for example follows the IECC 2018 codebook exactly with no amendments.

The IECC 2018 codebook states the following:

R402.4.1.2 Testing: The building or dwelling unit shall be tested and verified as having an air leakage rate not exceeding five air changes per hour in Climate Zones 1 and 2, and three air changes per hour in Climate Zones 3 through 8. Testing shall be conducted in accordance with RESNET/ICC 380, ASTM E779 or ASTM E1827 and reported at a pressure of 0.2 inch w.g. (50 Pascals). Where required by the code official, testing shall be conducted by an approved third party. A written report of the results of the test shall be signed by the party conducting the test and provided to the code official. Testing shall be performed at any time after creation of all penetrations of the building thermal envelope.

Most of Colorado and all of Denver is located in Climate Zone 4, meaning a blower door test has to result in 3 Air Changes Per Hours (ACH) or lower when running the blower door at 50 pascals of pressure.

While that’s a lot of jargon, the important thing to note is that 3 ACH is a fairly well sealed home. Most modern building techniques can achieve this easily, but it is important to ensure this in the back of your mind throughout the project.

Also, when picking materials, high-quality house wraps like zip system and air sealing insulation like spray foam can really help reduce air leakage. If you are interested in common air leaks, we have written a detailed article about that here. Also, if you are building a multi-family building in Denver, we have compiled a list of 7 items to be aware of when buildings have shared walls and accesses.

The only way to know a home’s air leakage is to test it. When blower door tests in Denver do not pass on their first try, our techs do their best to use thermal imaging to find hidden air leaks to seal.

Because of this, builders may choose to do a blower door test prior to drywall to find air leaks within the house wrap and framed walls. This is more common on larger projects.

Denver Blower Door Requirements on Additions

Additions where you are adding square footage to the home are subject to energy code compliance as well according to IECC 2018. The codebook states the following about existing structures:

R502.1.1.1Building envelope: New building envelope assemblies that are part of the addition shall comply with Sections R402.1, R402.2, R402.3.1 through R402.3.5, and R402.4.

Section R402.4 relates back to the blower door testing requirements from the previous section above. However, their wording states that only the new section of the home has to comply with these requirements.

This is a very difficult thing to test with a blower door as you cannot always block off only the new section of the home. Because of this, Denver had released an amendment to the code that states any retrofit or addition that adds 30% or more to the overall square footage of a home is required to do a blower door test on the home. When they do, they have the following options:

Additions larger than 30% of the existing floor area (not including basement area) have two options:

1. Perform a blower door test as a baseline before construction (to be submitted with the construction documents for plan review) and again once construction is complete (to be submitted at final inspection). The final blower door test must demonstrate the same air changes per hour (ACH) or less than the baseline. This path may be optimal for additions on older homes.

2. Or, only perform a final blower door test once construction is complete. The final blower door test must demonstrate five ACH or better. This does not require a baseline blower door test before construction, but could result in costs for improvements to the building envelope at the end of a project in order to meet five ACH.

This is pulled from the City & County Of Denver Community Planning & Development Building Permit Policy document which can be found here.

We always recommend builders opt for option number 1. While it requires an additional test, the chances of passing after construction are much higher, which can save you some headaches.

If you choose to go with option 2, just know that while 5 ACH is a fairly easy Denver blower door requirement to achieve, some older buildings, where the older side of the home is very leaky, can make this very difficult.

Staying Current On Energy Codes

While this article is accurate for 2021, energy codes are constantly changing. Just in July of 2021, Denver City Council voted to passed the 2019 Denver Green Code. This did not affect blower door requirements for residential properties unless you are using the performance pathway (ERI/HERS Rating) to gain compliance.

While HERS ratings and ERI is a different subject from this article, the point is that what is accepted today might not be the same in the future, so it is important to stay up to date. We do our best to keep all our clients informed with the most current energy code information.

If you are in need of a blower door test or a duct leakage test in the Denver area, contact us now and an energy specialist will help answer your questions and get your service scheduled!

Multi-family blower door testing is consistently becoming more common in all Colorado counties. Just as with a regular single family home, a multi-unit building will also need to have each unit pass a blower door test. This is typically required regardless of whether you are building a duplex or a 40-unit apartment building.

On top of that, the smaller the unit square footage is in an apartment building, the more difficult the test can be. Smaller footprints make achieving a 3ACH rating harder than a larger unit.

It is important for builders to think about their blower door testing requirements before construction starts. Once many of the air leaks are covered up with drywall, there is no way to seal them in a multi-unit building.

Because of this, we compiled some tips to help you with your next multi-family blower door test.

1. Exterior wall insulation:

We typically still see most builders using fiberglass batts during the construction of multi-family units. While this is a fine insulation product, it does very little to block air leakage.

We recommend using high-density blown-in products like cellulose in the walls. The packed insulation will provide a better air seal than batts. If possible, closed-cell foam is best, but this is a much more expensive product and is not always in the budget.
In this picture, you can see that air is moving through the wall cavities and in through the outlets and bottom edge.

2. Insulation between floors:

Between the drywalled ceiling of one unit and the floor of the above unit, the rim joists that meet the exterior walls and party walls should be sealed as tightly as possible. This is a commonly overlooked area as insulation is not typically required on the rim joists on large buildings.

However, the exterior wall coverings and wrap cannot stop all the air from getting into these floor joists. If not stopped, air typically will flow into the walls and through ceiling penetrations.

Many builders will spray-foam this section, which reduces exterior air moving through the floor cavities.

Be sure that you consider this when framing, because once the drywall is up, there is very little you can do about this large air leak.

Are you in need of a blower door test for your construction project in Colorado? Learn more about our services here!

3. House wraps:

Typically, house wrap is required on the exterior of the framing in Colorado, but not all wraps are created equal!

Plastic wrap on the exterior of the home can create a nice air barrier but non-ridged systems can rip, tear and be sealed incorrectly.

Consider using an exterior sheathing that claims to be a ridged air barrier such as Zip Wall System.

We have seen great improvements in homes that use this system top to bottom on the exterior of the home. This typically performs better than a Tyvek wrap.

4. Party Wall Mitigation:

Between units, a party wall with an air gap in between is required to prevent fires from spreading between units quickly. This is an important construction technique for fire safety, but can significantly contribute to air leakage.

Because the party wall runs the height of the building, the wall cavity is typically open at the top of the wall in the attic or elsewhere. This creates a large cavity for air to move from the vented attic, and into the unit through outlets, baseboard gaps and more.

See the image below for a visual representation of the top of the party wall.

These areas are usually insulated, but that often does not do enough to stop the air from entering the unit.

Sealing the top of the party wall with spray foam insulation will greatly reduce air flow between the shared wall sides of the units.

This way, air cannot run down from the attic, into this wall cavity, and through outlets and cracks. We also recommend sealing the areas where the party wall meets the exterior walls just like in tip 1.

Also, adding a plastic wrap over the insulation, similar to the exterior walls, can help these areas.

We cannot stress how important this step is especially in duplexes. This one fix can easily make you pass your multi-family blower door test.

The wall with the outlet in this photo is the party wall. Air is moving through this wall because of the air gap required for fire protection. Seal the tops and the sections where the air gap meets the exterior walls with closed-cell foam.

5. Sealing plates and bottom edges:

Many insulators will now offer air sealing packages where they seal the bottom and top plates around the exterior walls.

The gaps between the wood and the concrete or steel beams can be a source of air leakage.

After drywall, we highly recommend sealing the bottom edge of the drywall to the floor before baseboards are installed. Also, sealing the top plate of framed walls to the drywall should be done as well.

Sealing these sections will reduce air leaks around the edges/joints at exterior walls. This should typically be done before wall cavity insulation goes in.

This is still important to do if the unit has another unit above it. As we talked about in tip 2, floor joists can be prone to air leaks as well, but that air can be blocked by sealing these gaps at the top plate.

Here is a good shot of air moving through the wall cavity and into the unit through the bottom edge of the walls. Since all other areas of the wall are taped and sealed, this is a week section. Seal the plate and the drywall.

6. Sealing heat supply boots, fixtures, and ceiling penetrations:

Since most of your heat ducts run through the upper floor joists and attic, sealing the edges of the boots, junction boxes, and recessed lights that penetrate the ceiling drywall is very important.

We constantly see leaks around the edges of supply boots that run through the ceiling.

This is especially an issue on top floor units where the attic above is fully vented. Ensure that the top plates that meet that attic are sealed as well.

Here you can see around the edge of the J-box there is leakage. Also, you can see the cooler ceiling indicating air is likely moving through this area.

7. Bath Fans:

The bath fans pull in air when blower fans are run. While most bath fans have dampers that pull closed, it is typically not a perfect system.

Higher-end bath fans will reduce this issue, but if you are installing 100+ in a big apartment building, this might not be the most cost-effective solution.

We recommend adding an electronic or cape style damper within the vent line to prevent back-drafting of air through the fan.

These dampers work like check valves on water lines where air can only run one direction. Here is an example of the product.

This photo shows the air leaks back-drafting through the bath fan.

A Final Note.

If you are building a multi-family unit in which all the units will need to be tested, it may be in your best interest to do a pre-blower door test before drywall.

Once the windows and insulation are in, we can come and perform a pretest to see where some of the bigger leaks are occurring before they get covered up with drywall.

Doing this on a few of the units can save you a lot of headaches in the long run. We will take thermal images and talk you through areas that need sealing. It is better to be proactive than reactive.

If you have further questions about multi-family blower door testing, our energy specialists would be happy to take your call.