Blower Door Testing Explained: For the City of Phoenix (And Other Municipalities)

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blower door testing

If you are building new homes in the Phoenix metropolitan area, you have no doubt heard of the “blower door test” that’s required before you can get your certificate of occupancy. But what exactly is this “HERS testing” or “envelope leakage testing” that your building inspector is requiring? What firms are certified to do this testing? What are the steps to performing this test? Here’s a breakdown:

All Desert Skies Energy Inspectors are HERS Raters

Step 1: Identify a Qualified HERS Rating Organization
If it’s a code-required test for Phoenix or another municipality, you’ll need to make sure your energy inspection is performed by a certified HERS Rater. You can find qualified parties online at RESNET’s website. Desert Skies Energy is currently the top rated HERS Rating Organization in Arizona (per RESNET’s online ratings) and we provide competitive rates, two-day scheduling as well as reports printed on site and delivered immediately via email.

Step 2: Understand the Test & When to Schedule
The test measures how much air leakage is present in the home and duct system. It’s performed at the end of construction typically right after you’ve installed your weatherstripping and door exterior hardware. We typically tell our builders to test one week prior to calling for their final inspection. The test can be a formality if you’ve planned well and insulated with foam or opted for an air sealing package. If you’ve installed conventional batt insulation and haven’t thought too much about air sealing, this test might be tough to pass. The testing threshold is based on the cubic volume of the home– so we’ll need to know your livable square footage, average plate height and type of attic (sealed vs. vented).

Kevin Wiscombe performing a blower door test in Scottsdale, AZ

Step 3: Perform the Test
We’ll typically set up our iconic red canvas door on the garage service entry door. All trades must stay inside or outside the home for the duration of the test– which only takes around 5 minutes once set up. The preparation of the home can vary especially if there are custom details (e.g. fireplaces that are welded open that need to be blocked off). You prepare the home slightly differently if the house has a sealed attic versus a conventional vented attic. Once ready, the house is depressurized to 50 Pascals and the corresponding flow at this rate is recorded. That number is converted to an ACH50 (air changes per hour at 50 Pascals) which is compared to the code target. We’ll know immediately if you’ve passed or if we need to perform building diagnostics to discover the reason for failure.

Step 4: Receive Documentation + Label for SES
After the test is complete, a report is generated which includes the CFM50 blower door score as well as the ACH50 result. You should also include any other potential code required testing or inspections at this point (e.g. duct testing, air barrier and insulation inspections). Desert Skies Energy prints a hard copy for you on site and emails the electronic report directly to you inbox before we leave the jobsite. We also include an IECC label for each project that should be installed on the inside of the electrical panel– this includes features such as wall insulation, window U-Value and SHGC and more. We help our clients complete this document. If we’ve been to your project at rough, we likely have all this information already and will complete it for you entirely.

Step 5: Deliver Report + Receive Certificate of Occupancy
Once you’ve completed and passed your blower door test and any other required testing, you simply deliver your hard-copy report to your building inspector and inform him that the IECC label has already been completed and installed on your electrical panel. At this point, you are good to go!

Frequently Asked Questions:

Is the blower door test the only required energy code test?
No. Duct leakage testing is required for homes with duct work or mechanical equipment (air handlers, furnaces) outside the building envelope. We recommend this test be performed at rough-in before drywall is installed though it is possible to complete at final as well.

Does the City require insulation inspections? What about the “air barrier inspection” you’ve referenced?
Technically, either the building official or a RESNET HERS Rater needs to inspect your home for proper air sealing and insulation. Enforcement is lax here but becoming more common in areas like Scottsdale, where they’ve specifically started requiring a sign-off for air barrier and insulation inspections. Desert Skies Energy performs a complementary air barrier inspection for every project we duct test at rough.

What if I fail?
It happens. Typically, homes with vented attics are typically easier to repair than sealed attics. Most of the time, a simple work scope can be executed by general laborers with acrylic latex caulk. Homes with sealed attics that fail this test could have more significant problems like unsealed or missed knee walls. Desert Skies Energy has a company policy to diagnose any failures before leaving the jobsite. This means you’ll have simple to understand instructions on how to complete the repair. We even chat with your trades on your behalf to help expedite the process.

Got more questions?
Give us a call– our team is always happy to help!

Author: admin