Blower door testing (or air leakage testing) is an important part of the building process, as it determines the overall air tightness of a building, and helps to identify problematic leaks that may be present. As a result, it has been required for all new construction and additions since the 2015 IECC was released. Most CO municipalities have adopted the 2015 IECC by now. And many have moved on to the 2018 IECC and 2021 IECC.

When comparing the three different IECC iterations, their air leakage rules are fairly similar. However, the 2021 version of the IECC implemented a very important update with regards to attached single family, multi-family and small dwelling units.

Since more and more counties are moving toward the 2021 IECC standard, it’s a good idea to get acquainted with this update. As blower door testing specialists, it’s our job to stay on top of these things. So we decided to release an article, specifically about the air leakage section. Let’s dive in!

2021 IECC Air Leakage Testing Rules

As stated above, most of the of the air leakage testing rules have remained the same since the 2015 IECC. We have touched on these rules in a past blog. So if you need to get to up to speed, check out this article.

To summarize, a blower door test must be performed in any new construction or addition. All the windows, exterior doors, flues, and vents (where applicable) must be closed or sealed off during the test. The test must be conducted at a pressure of 50 Pascals; and the result must not exceed 3.0 air changes per hour (ACH) or 0.28 cubic feet per minute (CFM) in order to pass. These are tests that our energy services team has been performing throughout the CO Front Range for several years now.

So What’s the Update?

If you take a look at section R402.4.1.2, you will see that an exception has been added for air leakage testing. It reads:

Exception: When testing individual dwelling units, an air leakage rate not exceeding 0.30 cubic feet per minute per square foot of the dwelling unit enclosure area, tested in accordance with ANSI/RESNET/ICC 380, ASTM E779 or ASTM E1827 and reported at a pressure of 0.2 inch w.g. (50 Pa), shall be an accepted alternative permitted in all climate zones for:

1. Attached single-family and multiple-family building dwelling units.
2. Buildings or dwelling units that are 1,500 square feet or smaller.

This new update essentially allows you to utilize a different metric for attached single-family and multiple-family units or buildings that are under 1,500 square feet when testing each unit individually.

When conducting this test, the blower door specialist must measure the area of all floors, ceilings, and walls to the exterior of the dwelling to calculate its surface area. This means that walls/ceilings/floors shared with adjoining units do not need to be included in the surface area calculation. Next, they perform the blower door test at a pressure of 50 Pascals. We then take our total CFM reading, and divide it by the square feet of enclosure area. If the resulting number is at 0.30 CFM/sq ft or lower, the structure has passed the test.

What’s The Difference?

The main difference between the two air leakage tests is dimensions used for each respective formula and how the results are calculated.

For the original test:

The CFM/sq ft is calculated at 50 Pascals, then multiplied by 60 to yield the air changes per hour (ACH). Next, the square footage of the dwelling is multiplied by its ceiling height to calculate the volume of the space. Finally, the ACH is divided by the volume. The answer to this equation must equal 5 ACH or less in order to pass.

For the updated test:

The CFM/ sq ft is calculated at 50 Pascals. Then, the surface area of all floors, ceilings, and walls to the exterior are summed up (remember this excludes walls/ceilings/floors shared with other units). Then the CFM/sq ft is divided by the overall surface area of the dwelling. The resulting number must be 0.30 CFM/sq ft or lower in order to pass.

Is This Update a Good Thing?

Yes it is! This update has proven to be quite helpful for smaller dwellings. Most homes have similar components, regardless of size (i.e. doors, windows, ventilation penetrations, etc.). This means that whether the home is 5,000 sq ft or 1,200 sq ft, it will have to same potential areas for air leakage.

So during the traditional blower door test, a smaller home with the same amount of air leakage as a larger home is going to yield a higher ACH. For this reason small units have a difficult time yielding a passing test score. The updated test has made a passing score more attainable for small homes.

Multi-family and attached single dwellings (such as duplexes) especially benefit from this new exception. In the past, these types of buildings have had difficulty passing due to leakage occurring into adjacent apartments.

However, this type of leakage is not actually occurring to the exterior, and thus not actually an energy loss from the building as a whole. So that type of air leakage is not as big of a concern, from an energy stand point. As a result, the the new air leakage test allows the tester to omit these shared surfaces when calculating surface area.

Learn more about how to best prepare your multi-family building for blower door testing. Check out our article: 7 Tips For Multi-Family Blower Door Testing.

Blower Door Testing Services

Let’s face it, energy codes are strict. And as time passes by, they will probably continue to get stricter. That’s why it helps to have energy pros on your side to help you reach compliance each step of the way. At Scott Energy Services, a division of Scott Home Services, blower door testing is one of our flagship services. With a team of highly trained, experienced and professional energy specialists, we are equipped to help meet your project deadlines.

If you need an air leakage test or any other energy services, we encourage you visit us online or contact our energy service team today!

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.

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.