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3799 Main St. #87024
Atlanta, GA 30337
USA

773.398.5288

Advanced residential construction and home improvement consulting and owner's advocacy in Atlanta, using the latest building performance diagnostic and modeling techniques and tools. Airtightness, insulation, HVAC, ventilation, moisture, and air quality and EMF consulting for homeowners and building professionals alike.

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Home performance articles and stories from the field with internationally respected building forensics guru Corbett Lunsford at the Building Performance Workshop. Hear new episodes of the Building Performance Podcast, see new videos from the Home Performance YouTube channel, and learn all about how diagnostic testing (more than an 'Energy Audit') can make home improvement and new home construction a proven process!

DEAR CORBETT: Multifamily Blower Door Testing Nuances

Corbett Lunsford

Good day Corbett,

I wanted to let you know, that I really enjoy your approach to the whole building science and your building performance workshop website. I am relatively new as a Resnet Rater and the county where I live is Collier County in Florida.

They recently adopted the new code standard set by the state. My question relates to multifamily condo units. I have a client that did renovations to a 2,500 sq. ft. penthouse condo and the front door to the unit is I a common area. The county wants them to perform a blower door test in order to obtain their certificate of occupancy.

I realize this would be a compartmentalize test, since I can only have access to the unit they renovated for their client. Knowing that I will encounter not only leakage to outside but also internal leakage between units. I was wondering what the best approach would be to ensure a successful test. Collier County requires between 3 ach and 7 ach for a test to pass code.

Any information would be appreciated. Thanking you in advance.

Best Regards,
Norm Giguere
www.blowerdoorenergyexperts.com


Dear Norm-

Thanks for your question, it's a good one! First off, you should be fine if they did a good job with the renovations- 7 ACH50 is not terribly hard to achieve.

When you set up your blower door at the front door of the condo, you'll blow air out into the common hallway, so you want to make sure all possible windows/doors in that hallway are open to the outdoors. Use the emergency exits if necessary (make sure maintenance knows what you're up to).

You'll be testing the condo's leakage to everything outside of it, including the downstairs unit, but that's intended. They really will have air leaking between the two condos, if there are leakage pathways, and you want to be testing for that and including it in your blower door test result.

Ask your code official if they want the result to pass the residential code or commercial code, because you have to test at 75 Pa in commercial. I always advise doing a multipoint test (get the flows on at least two pressures, like 25 Pa and 50 Pa) so you can extrapolate the 75 Pa if anyone ever wants it in the future. Saves you a trip.

AS AN ADDED BONUS, consider doing a Zonal Pressure Test on the unit downstairs, to see how much the blower door is affecting it. Always nice to have more data than you need.

Happy Testing,
Corbett