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New Construction Duct Testing Blower Door

The 2018 WA State Energy Code (WSEC) section 101.3.2.6 requires that ducts be tested in homes which replace any of the following equipment:

  • Whole furnace system 
  • Air handler
  • Outdoor condensing unit (AC or HP) 
  • Cooling or heating coils 
  • Furnace heat exchanger 

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 be tested for this standard by a third party blower door specialist.

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 the 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 ductwork 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, homeowners 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.

2018 Energy Code:

R403.3.3 Duct testing. Ducts shall be leak tested in accordance with WSU RS-33, using the maximum duct leakage rates specified.

Exceptions: 1. The total leakage test or leakage to the outdoors is not required for ducts and air handlers located entirely within the building thermal envelope. For forced air ducts, a maximum of 10 linear feet of return ducts and 5 linear feet of supply ducts may be located outside the conditioned space. All metallic ducts located outside the conditioned space must have both transverse and longitudinal joints sealed with mastic. If flex ducts are used, they cannot contain splices. Flex duct connections must be made with nylon straps and installed using a plastic strapping tensioning tool. Ducts located in crawl spaces do not qualify for this exception.

2. A duct air leakage test shall not be required for ducts serving heat or energy recovery ventilators that are not integrated with ducts serving heating or cooling systems. A written report of the results shall be signed by the party conducting the test and provided to the code official.

2018 Washington State Energy Code RE-31 < R403.3.4 Duct leakage.

The total leakage of the ducts, were measured in accordance with Section R403.3.3, shall be as follows:

1. Rough-in test: Total leakage shall be less than or equal to 4 cfm (113.3 L/min) per 100 square feet (9.29 m2 ) of conditioned floor area when tested at a pressure differential of 0.1 inches w.g. (25 Pa) across the system, including the manufacturer's air handler enclosure. All registers shall be taped or otherwise sealed during the test. If the air handler is not installed at the time of the test, total leakage shall be less than or equal to 3 cfm (85 L/min) per 100 square feet (9.29 m2 ) of conditioned floor area.

2. Post-construction test: Leakage to outdoors shall be less than or equal to4 cfm (113.3 L/min) per 100 square feet (9.29 m2 ) of conditioned floor area or total leakage shall be less than or equal to 4 cfm (113.3 L/min) per 100 square feet (9.29 m2 ) of conditioned floor area when tested at a pressure differential of 0.1 inches w.g. (25 Pa) across the entire system, including the manufacturer's air handler enclosure. All register boots shall be taped or otherwise sealed during the test.

Duct Sealing:

R403.3 Ducts. Ducts and air handlers shall be installed in accordance with Sections R403.3.1 through R403.3.7. R403.3.1 Insulation. Ducts outside the building thermal envelope shall be insulated to a minimum of R-8. Ducts within a concrete slab or in the ground shall be insulated to R-10 with insulation designed to be used below grade. Exception: Ducts or portions thereof located completely inside the building thermal envelope. Ducts located in crawl spaces do not qualify for this exception. R403.3.2 Sealing. Ducts, air handlers, and filter boxes shall be sealed. Joints and seams shall comply with either the International Mechanical Code or International Residential Code, as applicable. Exceptions: 1. Air-impermeable spray foam products shall be permitted to be applied without additional joint seals. 2. For ducts having a static pressure classification of less than 2 inched of water column (500 Pa), additional closure systems shall not be required for continuously welded joints and seams, and locking-type joints and seams of other than the snap-lock and button-lock types. R403.3.2.1 Sealed air handler. Air handlers shall have a manufacturer's designation for an air leakage of no more than 2 percent of the design air flow rate when tested in accordance with ASHRAE 193

2018 Blower Door Testing

R402.4.1.2 Testing. 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). For this test only, the volume of the home shall be the conditioned floor area in ft2 (m2 ) multiplied by 8.5 feet (2.6 m). 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 the creation of all penetrations of the building thermal envelope. Once the visual inspection has confirmed sealing (see Table R402.4.1.1), operable windows and doors manufactured by small businesses shall be permitted to be sealed off at the frame prior to the test. Exception: For dwelling units that are accessed directly from the outdoors, other than detached one-family dwellings and townhouses, an air leakage rate not exceeding 0.4 cfm per square foot of the dwelling unit enclosure area shall be an allowable alternative. Testing shall be conducted with a blower door at a pressure of 0.2 inches w.g. (50 Pascals) in accordance with RESNET/ICC 380, ASTM E779 or ASTM E1827. For the purpose of this test only, enclosure area to be calculated as the perimeter of the dwelling unit, measured to the outside face of the exterior walls, and the centerline of party walls, times 8.5 feet, plus the ceiling and floor area. Doors and windows of adjacent dwelling units (including top and bottom units) shall be open to the outside during the test. This exception is not permitted for dwelling units that are accessed from corridors or other enclosed common areas.

During testing:

1. Exterior windows and doors, fireplace and stove doors shall be closed, but not sealed, beyond the intended weatherstripping or other infiltration control measures.

2. Dampers including exhaust, intake, makeup air, backdraft and flue dampers shall be closed, but not sealed beyond intended infiltration control measures.

3. Interior doors, if installed at the time of the test, shall be open, access hatches to conditioned crawl spaces and conditioned attics shall be open.

4. Exterior or interior terminations for continuous ventilation systems and heat recovery ventilators shall be sealed.

5. Heating and cooling systems, if installed at the time of the test, shall be turned off.

6. Supply and return registers, if installed at the time of the test, shall be fully open.

Exceptions:

1. Additions less than 500 square feet of conditioned floor area.

2. Additions tested with the existing home having a combined maximum air leakage rate of 7 air changes per hour. To qualify for this exception, the date of construction of the existing house must be prior to the 2009 Washington State Energy Code.

Call us today to learn how we can better help you comply with the 2018 Washington State Energy Code - PTCS  call 425.608.9553 for independent Blower Door and Duct Testing