New Construction Duct Testing Blower Door

Author: Pacific Northwest Inspections Group, LLC   Date: 25-Nov-2013.   Category: Energy Effiency   Add to Favorites 

The 2015 WA State Energy Code (WSEC) section requires that ducts be tested in homes which replace any of the following equipment:

The ducts must be tested in accordance with the requirements of RC-33 for total leakage. An affidavit must be completed by a qualified technician approved by the state, which must be submitted to the code official.

Pacific Northwest Inspections Group employees are certified to perform duct testing to the RC-33 standard, and has extensive qualifications and experience with duct testing in residential homes and commercial buildings.

In addition, we have the experience and specialized testing equipment needed to help contractors in troubleshooting ducting systems that are particularly difficult to seal with elusive holes and leaks.

Duct testing can be time consuming and difficult task to get good results, but you can rely on Pacific Northwest Inspections Group to help you save money and give you and your clients the best possible information about their home. They will appreciate our service and fell confident in the work that was performed.


What is a Blower Door Test?

Blower door testing is a scientific way to test the air leakage of any given structure. By depressurizing the building and measuring the rate at which air infiltrates the building envelope through any number of imperfections in the structure.

Is it required?

Per R402.4.1.2, this test is required to be done on every new construction home, additions over 500sf and all multi family buildings. As of July 1st 2016 the standard has been set to less than 5 ACH @50 pascals (air exchanges per hour). Your project must meet this standard.

What is Washington R402.4.1.2?

The building or dwelling unit shall be tested and verified as having an air leakage rate of not exceeding 5 air changes per hour. Testing shall be conducted with a blower door at a pressure of 0.2 inches 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.

Once visual inspection has confirmed sealing (see Table R402.4.1.1), operable windows and doors manufactured by small business shall be permitted to be sealed off at the frame prior to the test.

The first step to making your house tighter and more efficient is to schedule a Performance Test for your home. PNWIG's technicians are specially trained and PTCS Certified, so you can be sure that when your Duct and Blower Door tests are performed, and your duct work is sealed, all work will meet or exceed new building code standards. 

Air flowing in and out of a building can cause lots of problems; in fact, air leakage can account for 30 percent to 50 percent of the heat loss in some homes. But air flowing through a building can help solve lots of problems too — as long as it’s the result of a blower-door test. With a blower door, builders, contractors, home owners can quantify airflow and the resulting heat (or cooling) loss, pinpoint specific leaks, and determine when a home needs additional mechanical ventilation.

Once we have used flow and pressure to determine what the leaks are like, we can use that hole description, along with weather and site data (the test pressure), to estimate the airflow that can be expected under normal conditions. But estimates of “natural airflow” are inherently inaccurate, because it’s difficult to know how the wind blows on a particular site, or what the occupant behavior is like, or how the mechanical equipment interacts with the building. So it’s important to know whether airflow descriptions are measurements of leakage under specified conditions or estimates of airflow under normal conditions.

To measure airflow, a closed-up house is depressurized with the blower-door fan to a constant pressure differential as compared with outside conditions, typically 50 pascals (Pa). A pressure gauge attached to the blower-door assembly measures the rate of airflow required to maintain that pressure differential in cfm (cubic feet per minute).

Sometimes several readings are taken at different pressures, then averaged and adjusted for temperature using a simple computer program. This provides the most accurate picture of airflow, including leakage ratios, correlation coefficients, and effective leakage area.

Most of the time, though, this detailed output isn’t needed, and all we want to know is how much the building leaks at the specified reference pressure of 50 Pa. So-called single-point testing is popular with crews who do retrofit work, because once the door is set up, it takes only about a minute to measure the effectiveness of their air-sealing strategies.

Call us today to learn how we can better help you comply with the 2015 Washington State Energy Code - PTCS  425.608.9553.