Multi Point Blower Door Testing

Multi-point tests collect the airflow data (in cfm) at five different pressure levels between 10 pascals and 60 pascals, while single-point blower door tests collect the airflow data (in cfm) at only one pressure level, typically 50 pascals.

What happens if you are unable to reach at least 50 Pascals of pressure during multi-point testing?  The 380 standard will allow a multi-point test to be used as long as at least 25 Pascals of pressure can be reached.  Less than 25 Pascals and the test is required to be a single-point test.  

Air Duct Testing

REVISED EFFECTIVE DATE FOR 2021 CODES - MARCH 15, 2024

The State Building Code Council voted on May 24, 2023, to delay the effective date of the 2021 codes for 120 days, which changed the effective date from July 1, 2023 to October 29, 2023. On September 15, 2023, the State Building Code Council agreed on another delay. The new effective date for all building codes is March 15, 2024.

The Council is also entering rulemaking to modify sections in the commercial and residential energy codes to address legal uncertainty stemming from the decision in California Restaurant Association v. City of Berkeley recently issued by the Ninth Circuit Court of Appeals.

R403.3 Ducts.

Ducts and air handlers shall be installed in accordance with Sections R403.3.1 through R403.3.7.

R403.3.1 Ducts located outside conditioned space Supply and return ducts located outside conditioned space shall be insulated to an R-value of not less than R-8 for ducts 3 inches (76 mm) in diameter and larger and not less than R-6 for ducts smaller than 3 inches (76 mm) in diameter. Ducts buried beneath a building shall be insulated as required per this section or have an equivalent thermal distribution efficiency. Ducts within a concrete slab or in the ground shall be insulated to R-10 with insulation designed to be used below grade. Underground ducts utilizing the thermal distribution efficiency method shall be listed and labeled to indicate the R-value equivalency. R403.3.2 Ducts located in conditioned space.

For ducts to be considered as being located inside a conditioned space, such ducts shall comply with one of the following:

1. All duct systems shall be located completely within the continuous air barrier and within the building's thermal envelope.

2. All heating, cooling, and ventilation system components shall be installed inside the conditioned space including, but not limited to, forced air ducts, hydronic piping, hydronic floor heating loops, convectors and radiators. Combustion equipment shall be a direct vent or sealed combustion.

3. For forced air ducts, a maximum of 10 linear feet of return ducts and 5 linear feet of supply ducts is permitted to be located outside the conditioned space, provided they are insulated to a minimum of R-8. 3.1. Metallic ducts located outside the conditioned space must have both transverse and longitudinal joints sealed with mastic. 3.2. 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.

4. Ductwork in floor cavities located over unconditioned space shall comply with all of the following: 4.1.A continuous air barrier installed between unconditioned space and the duct. RE-32 2021 Washington State Energy Code < 4.2. Insulation was installed in accordance with Section R402.2.7. 4.3.A minimum R-19 insulation installed in the cavity width separating the duct from unconditioned space.

5. Ductwork located within exterior walls of the building thermal envelope shall comply with the following: 5.1.A continuous air barrier installed between unconditioned space and the duct. 5.2. Minimum R-10 insulation installed in the cavity width separating the duct from the outside sheathing. 5.3.The remainder of the cavity insulation shall be fully insulated to the drywall side. R403.3.3 Ducts buried within ceiling insulation.

Where supply and return air ducts are partially or completely buried in ceiling insulation, such ducts shall comply with all of the following:

1. The supply and return ducts shall have an insulation R-value not less than R-8. 2. At all points along each duct, the sum of the ceiling insulation R-value against and above the top of the duct, and against and below the bottom of the duct, shall be not less than R-19, excluding the R-value of the duct insulation. Exception: Sections of the supply duct that are less than 3 feet (914 mm) from the supply outlet shall not be required to comply with these requirements. R403.3.3.1 Effective R-value of deeply buried ducts. Where using the Total Building Performance compliance option in Section R405, sections of ducts that are: installed in accordance with Section R403.3.3; located directly on, or within 5.5 inches (140 mm) of the ceiling; surrounded with blown-in attic insulation having an R-value of R-30 or greater and located such that the top of the duct is not less than 3.5 inches (89 mm) below the top of the insulation, shall be considered as having an effective duct insulation R-value of R-25. R403.3.4 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 fewer than 2 inches 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. R403.3.4.1 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. R403.3.5 Duct testing. Ducts shall be leak tested in accordance with WSU RS-33, using the maximum duct leakage rates specified.

Exception: A duct air leakage test shall not be required for ducts serving ventilation systems 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. R403.3.6 Duct leakage.

The total leakage of the ducts, where 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 4.0 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 3.0 cfm (85 L/min) per 100 square feet (9.29 m2 ) of conditioned floor area. 2021 Washington State Energy Code RE-33 *

2. Postconstruction test: Leakage to the outdoors shall be less than or equal to 4 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.

3. Test for ducts within a thermal envelope: Where all ducts and air handlers are located entirely within the building thermal envelope, total leakage shall be less than or equal to 8.0 cubic feet per minute (226.6 L/min) per 100 square feet (9.29 m2) of conditioned floor area. 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.

Passing Duct Sealing Testing the 1st Time

Sealing all joints with adequate mastic is key to an airtight duct system. Mastic should be installed as thick as a nickel along every joint.

Below are some examples of jobs that pass the first time, joints were taped and thick mastic was applied.

Very clean joints, a crew that cares: Job by Cardinal Heating and Cooling -

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Joints of duct systems shall be made substantially airtight by means of tapes, mastics, liquid sealants, gaskets, or other approved closure systems. Closure systems used with rigid fibrous glass ducts shall comply with UL181A and shall be marked 181A-P for pressure-sensitive tape, 181A-M for mastic, or 181 A-H for heat-sensitive tape. Closure systems used with flexible air ducts and flexible air connectors shall comply with UL 181B and shall be marked 181B-FX for pressure-sensitive tape or 181B-M for mastic. Duct connections to flanges of air distribution system equipment or sheet metal fittings shall be mechanically fastened. Mechanical fasteners for use with flexible nonmetallic air ducts shall comply with UL 181B and shall be marked 181B-C. Crimp joints for round metal ducts shall have a contact lap of at least 1¹/₂ inches (38 mm) and shall be mechanically fastened by means of at least three sheet-metal screws or rivets equally spaced around the joint. Closure systems used to seal metal ductwork shall be installed in accordance with the manufacturer's installation instructions.

Exceptions:

1. Spray polyurethane foam shall be permitted to be applied without additional joint seals.
2. Where a duct connection is made that is partially inaccessible, three screws or rivets shall be equally spaced on the exposed portion of the joint so as to prevent a hinge effect.
3. Continuously welded and locking type longitudinal joints and seams in ducts operating at static pressures less than 2 inches of water column (500 Pa) pressure classification shall not require additional closure systems.

2021 IECC

Total leakage Duct Testing ONLY !!! Prevent HVAC Comfort issues in your new home by only accepting a TL test.

Blower Door Testing & Air Sealing

 ⚠️ Scroll to the end to see Air Seal techniques ⚠️

REVISED EFFECTIVE DATE FOR 2021 CODES - MARCH 15, 2024

The State Building Code Council voted on May 24, 2023, to delay the effective date of the 2021 codes for 120 days, which changed the effective date from July 1, 2023 to October 29, 2023. On September 15, 2023, the State Building Code Council agreed on another delay. The new effective date for all building codes is March 15, 2024.

The Council is also entering rulemaking to modify sections in the commercial and residential energy codes to address legal uncertainty stemming from the decision in California Restaurant Association v. City of Berkeley recently issued by the Ninth Circuit Court of Appeals.

Based on the 2021 IECC. Please note that "Residential" includes One- and Two-family dwellings, Townhouses, and  R-3 buildings three stories or less, and Group R-2 buildings three stories or less with dwelling units that are accessed directly from the exterior. "Commercial" includes all buildings not covered under "Residential." 

Pacific Northwest Inspections Group offers blower door tests and duct leakage tests that are both energy-saving and in compliance with Washington State’s required Air Leakage Testing (R402.4.1.2)

WASHINGTON STATE - SAME-DAY TESTING CALL 425.608.9553 for a Blower Door Test Today!

R402.4 Air leakage.

The thermal building envelope shall be constructed to limit air leakage following Sections R402.4.1 through R402.4.6 requirements. R402.4.1 Building thermal envelope air leakage. The building thermal envelope shall comply with Sections R402.4.1.1 through R402.4.1.3. The sealing methods between dissimilar materials shall allow for differential expansion and contraction. R402.4.1.1 Installation. The components of the building thermal envelope, as listed in Table R402.4.1.1 shall be installed following the manufacturer's instructions and the criteria listed in Table R402.4.1.1, as applicable to the construction method. Where required by the code official, an approved third party shall inspect all components and verify compliance.

R402.4.1.2 Testing. The building or dwelling unit shall be tested for air leakage. Testing shall follow RESNET/ICC 380, ASTM E779, or ASTM E1827. Test pressure and leakage rate shall comply with Section R402.1.3. A written report of the test results, including verified location and time stamp of the test date, shall be signed by the testing agency and provided to the building owner and code official. Testing shall be performed at any time after the creation of all penetrations of the building's thermal envelope. Once visual inspection has confirmed air sealing has been conducted in accordance with Table R402.4.1.1, operable windows and doors manufactured by small businesses are permitted to be sealed off at the frame prior to the test. Testing of single-family dwellings and townhouses shall be conducted in accordance with RESNET/ICC 380. Test pressure and leakage rate shall comply with Section R402.1.3.1. For Group R-2 occupancies, testing shall be conducted in accordance with ASTM E779, ASTM E1827, or ASTM E3158. Test pressure and leakage rate shall comply with Section R402.1.3.2. The individual performing the air leakage test shall be trained and certified by a certification body that is, at the time of permit application, an ISO 17024 accredited certification body including, but not limited to, the Air Barrier Association of America.

R402.4.1.3 Leakage rate.

Detached one- and two-family dwellings and multiple single-family dwellings (townhouses) shall comply with Section R402.4.1.3.1. Group R-2 multifamily buildings shall comply with Section R402.4.1.3.2. R402.4.1.3.1 Dwelling unit leakage rate. The maximum air leakage rate for any dwelling unit under any compliance path shall not exceed 4.0 air changes per hour. Testing shall be conducted with a blower door test at a test pressure of 0.2 inches w.g. (50 Pa).

Exception: 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 dwelling must be prior to the 2009 Washington State Energy Code. R402.4.1.3.2 Group R-2 multifamily building leakage rate. For Group R-2 multifamily buildings, the maximum leakage rate for any dwelling unit shall not exceed 0.25 cfm per square foot of the dwelling unit enclosure area. Testing shall be conducted with a blower door at a test pressure of 0.2 inches w.g. (50 Pa). Doors and windows of adjacent dwelling units (including top and bottom units) shall be open to the outside during the test.

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, and 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. 2021 Washington State Energy Code RE-27

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. Exception: Additions less than 500 square feet of conditioned floor area.

Fail a test? Seal the building tight with AeroBarrier.

AeroBarrier is an interior-applied air sealing system that seals building envelope leaks up to 1/2″. The waterborne sealant is aerosolized and injected into a pressurized home. The sealant is self-guided to the edges of visible and invisible leaks to create a seal by accumulating across the leaking surface. The sealant is applied within 60-90 minutes and dries quickly before the system cleanup is complete. This ensures construction can resume shortly after the process is complete with little to no impact on standard construction schedules. The AeroBarrier system measures envelope leakage in real-time, enabling the system to dial in specific air leakage requirements with precision and guarantee the results.

AeroBarrier is not used by the pros. Building it right the first time shouldn't be needed. Many high-end builders are questioning the durability this system will provide years from install. Will failure be an issue? We will find out!

Foam in place has sealed houses to as low as 0.19 ACH50. But the value is in the system’s ability to allow builders to seal a home to as tight as it is designed for. AeroBarrier can meet any IECC, Passive House, LEED, Well Standard, ENERGY STAR, or Net Zero requirement, but is it the way to go?

Need AeroSeal sealing? You shouldn't when you build it right. Contact us at 425.608.9553. for testing

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Washington State Energy Code 2012

Your whole house fan capacity was selected based on the size of the house, and the number of bedrooms. The table below shows the required continuous ventilation rates (in CFM) for homes of various sizes. 

In many cases, a bathroom fan may do double-duty as the local exhaust and the whole house fan. These fans may have a control that sets the continuous operation ventilation rate (in CFM) and a sensor that ramps the fan up to a higher CFM when the room is occupied. This sensor can be set to run the fan for a specific period of time after the occupant leaves the room before it ramps down to the lower CFM rate. 

302.3.1 Whole House Ventilation Systems: Each dwelling unit shall be equipped with a whole house ventilation system which shall be capable of providing the volume of outdoor air specified in Table 3-2 under normal operating conditions. 

302.3.2 Whole House Ventilation System Controls: All ventilation system controls shall be readily accessible. Controls for whole house ventilation systems shall be capable of operating the ventilation system without energizing other energy-consuming appliances. 

Intermittently operated whole-house ventilation systems shall be constructed to have the capability for continuous operation and shall have a manual control and an automatic control, such as a clock timer. At the time of final inspection, the automatic control timer shall be set to operate the whole house fan for at least 8 hours a day with a fan rated for CFM noted in the table. A label shall be affixed to the control that reads “Whole House Ventilation (see operating instructions).” 

302.3.4 Whole House Ventilation Ducts: All ducts shall terminate outside the building. Exhaust ducts in systems that are designed to operate intermittently shall be equipped with back-draft dampers. All exhaust ducts in unconditioned spaces shall be insulated to a minimum of R-4. All supply ducts in the conditioned space shall be insulated to a minimum of R-4. We recommend meeting this requirement in older homes previous to this code change as well.

A properly ventilated home means good moisture control !!  Moisture = Mold and Decay!

We Test for WA State 2012 Energy Code, Call us @ 425.608.9553 for your Energy Audit and Ventilation Needs -

Note: This service is not standard in a home inspection and is an additional service. Like to add this service to your inspection? Just mention Whole House Fan certification to the inspector, our inspectors are all trained for Residential and Commercial Energy Auditors! Call today 425.608.9553.

Air Sealing with AeroBarrier 

Washington State is home to many rodents that will work night and day to gain access to your warm crawlspace and attic. They chew through plastic, wood, and even light gauge screening. Protecting your building from their access is not only recommended but even has a building code on how it needs to be done.

Yes, there is even a building code stating how access points into the Attic and Crawlspace need to be secured. Exterior openings into the attic space of any building intended for human occupancy shall be protected to prevent the entry of birds, squirrels, rodents, snakes, and other similar creatures.

Openings for ventilation having a least dimension of 1/16 inch (1.6 mm) minimum and 1/4 inch (6.4 mm) maximum shall be permitted. Openings for ventilation having a least dimension larger than 1/4 inch (6.4 mm) shall be provided with corrosion-resistant wire cloth screening, hardware cloth, perforated vinyl or similar material with openings having a least dimension of 1/16 inch (1.6 mm) minimum, and 1/4 inch (6.4 mm) maximum. Where combustion air is obtained from an attic area, it shall be in accordance with Chapter 7 of the International Mechanical Code 701.1 - 708.1.

Need help with air sealing call us 425.608.9553

Save up to 25% on your home energy bills and make your home more comfortable to live in! With ever-rising energy costs in Seattle, WA and around the Puget Sound area your savings will begin to quickly multiply.

Home energy bills are the second largest cost of owning a home. A home energy analyzed by Pacific Northwest Inspections Group is quick, easy, and cost effective. It is a tried and tested way to pinpoint and reduce energy loss and is approved by Government Tax rebate programs in the US. We will inspect your home, collect data, and input the data into a energy software that will produce an easy to read report, including pictures and graphs, showing what energy wasting items and improvement can be performed to save you money. 

What a Audit can do for you:

• Save an average of up to 25% on your energy bill;
• Find out which improvements to make - the report will estimate the savings and costs of each potential upgrade;
• Increase the comfort of your home - no drafts, better temperature control;
• Increase the value of your home - each dollar spent on recommended improvements will increase the future sales value by more than a dollar.

We are certified energy specialist and use state-of-the-art equipment to aid in the diagnosis of wasted energy. During the home energy inspection and data collection I will incorporate a blower door and or duct blaster test to depressurize the house and use an infrared thermal camera to show you exactly where the energy is being lost. “A home energy inspection without the use of a blower door and an infrared camera is not a complete energy inspection.”

How The Process Works

Step 1: The Home Energy Inspection

• To reduce utility bills, the first step is to find out where you are wasting energy.
• To do this, you need a residential energy inspection—which should be done by a certified energy inspector who has no financial interest in the improvements recommended.
• The energy inspector will examine, measure, and evaluate the factors that affect energy use in your home, e.g., size of the home, efficiency of appliances, insulation, draftiness of rooms, and efficiency of heating and cooling systems (HVAC). This includes using state of the art Infrared Thermal Imaging Technology and blower door equipment.

Step 2: The Energy Inspection Report Detailed Analysis

• The information gathered during the energy audit is analyzed using specialized software to produce a comprehensive Home Energy Report. The Report shows which energy-efficiency improvements would reduce energy costs and make the home more comfortable. The analysis takes into account regional variables such as local weather, implementation costs, and fuel prices.
• The Report contains estimates of the savings, costs and payback for each energy-efficiency recommendation. It identifies the group of improvements that, if financed, will save more on energy bills than it costs. These are the improvements that everyone can make since they require no out-of-pocket cost when financed.
• The detailed Recommendations section enables contractors to provide preliminary cost estimates without a visit to your home. It also explains how to get the best energy savings from these improvements by listing related no-cost low-cost measures that you can take.

Step 3: The Home Energy Inspection

Pacific Northwest Inspections Group also has a list of preferred contractors that we have personally worked with and can aid you in selecting a qualified person.

Step 4: Financing Home Energy Savings

Energy improvements are unique because they reduce energy bills thereby increasing disposable income.

Financing energy efficiency improvements as part of your home mortgage is the best way to go. You have the advantage of (1) low monthly payments due to a 30-year term and a relatively low interest rate; and (2) interest that is deductible from your income tax.

The improvements listed in the Improvements that Save More than they Cost section of the Report will automatically qualify for financing since they increase the value of the house without reducing disposable income. Information about Energy Loans, Incentives, and Initiatives will be included in the Report.

Pacific Northwest Inspections Group performs Home Energy Inspections in Seattle and throughout the Puget Sound area. Our reports are approved for Lenders and Government rebates/ loan approvals. We offer HERS rating and Energy Start Home Certification as well.

For information regarding low-to-no interest energy loans. Or for information on the Federal Government, and Washington State, energy tax credits, please contact us today.

Find the Energy Leaks Virtural Tour !!!!

2021 Washington State Energy Code

• WAC 51-11C (Commercial)  2nd Printing
  (1st Printing missing Section C403.1.4)
    
• WAC 51-11R (Residential)  1st Printing
  Copy of Appendix A from the Commercial Provisions (Default Heat Loss Coefficients)

Effective July 1, 2023.

Based on the 2021 IECC. Please note that "Residential" includes One- and Two-family dwellings, Townhouses, and  R-3 buildings three stories or less, and Group R-2 buildings three stories or less with dwelling units that are accessed directly from the exterior. "Commercial" includes all buildings not covered under "Residential." 

R402.4.1.3 Leakage rate. Detached one- and two-family dwellings and multiple single-family dwellings (townhouses) shall comply with Section R402.4.1.3.1. Group R-2 multifamily buildings shall comply with Section R402.4.1.3.2. R402.4.1.3.1 Dwelling unit leakage rate. The maximum air leakage rate for any dwelling unit under any compliance path shall not exceed 4.0 air changes per hour - 4ACH Testing shall be conducted with a blower door test at a test pressure of 0.2 inches w.g. (50 Pa). Exception: 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 dwelling must be prior to the 2009 Washington State Energy Code.

R402.4.1.3.2 Group R-2 multifamily building leakage rate. For Group R-2 multifamily buildings, the maximum leakage rate for any dwelling unit shall not exceed 0.25 cfm per square foot of the dwelling unit enclosure area. Testing shall be conducted with a blower door at a test pressure of 0.2 inches w.g. (50 Pa). Doors and windows of adjacent dwelling units (including top and bottom units) shall be open to the outside during the test.

As an approved, independent third-party company, we'll help you meet state code compliance. Code-compliant testing with a Washington State Energy Code Compliance Certificate.

The WA State Energy Code (WSEC) section 101.3.2.6 requires that ducts be tested in homes that 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 new 2021 Washington State Energy Code for commercial and residential projects is available online from the Washington State Building Code Council.  

Our integrative design teams are hard at work with partners on several projects that fall under these new provisions.

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 and must be submitted to the code official.

Pacific Northwest Inspections Group employees are certified to perform duct testing to the RC-33 standard and have 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 a 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 homes. They will appreciate our service and feel confident in the work that was performed.

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, and 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, 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.

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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's 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, 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 the conditioned floor area.

2. Post-construction test: Leakage to the 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's 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's 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 fewer than 2 inches of water column (500 Pa), additional closure systems shall not be required for continuously welded joints and seams, and locking-type joints and seams 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's 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, the enclosure area is 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, and 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, CFM Verification, and Air Duct Testing

Home Ventilation

Range Hood / Microwave Duct sizing and the proper size of ductwork for your new Vent Hood are very important to ensure that your Microwave or Vent Hood is efficient and quiet.

The diameter of your Range Hood Ductwork by far is the most important factor.

The diameter of your Ductwork is the single most important consideration. Here are some guidelines based on your Vent Hood CFM. Now please note that we will use the most commonly available sizes of Ductwork for our recommendations and that in many remodel applications for older homes there is an existing 4” Duct which in some cases is the only option other than a recirculating hood. We always recommend venting outside over recirculating even if you must adapt to an existing smaller duct size than is recommended. If you have any questions please call us or contact your local HVAC professional.

• 0-400 CFM Minimum Duct Size of 4” Recommended Duct Size of 6” if possible
• 401-600 CFM Minimum Duct Size of 6” - Recommended Duct Size of 8” if possible
• 601-900 CFM Minimum Duct Size of 7” - Recommended Duct Size of 8”-10” if possible
• 901-1200 CFM Minimum Duct Size of 8” -Recommended Duct Size of 10”-12” if possible
• 1200 CFM and above will depend on the motor type and duct run length but at least a 10” diameter duct is required and 12” is recommended by manufactures

The recommendations for Range Hood Ductwork Size are suggestions. After you consider the size of your Ductwork the next most important factor is the “Run”. How long is the ductwork and how hard will the Range Hood Blower have to “push” the exhaust air to get it out of ductwork? Always follow the manufacturer installation requirements for any installation.

Microwave units also state in the manufacturer specs that a minimum of 6" round should be used or 3 1/4" x 10" rectangular 

The length of Ductwork and the number of changes in direction are the second most important factors.

Next to Ductwork Size, the Length is the most important consideration. In some cases even if you are dramatically undersized you can still exhaust the cooking air efficiently if you have a very short run of ductwork. Here are the necessary things to consider in the ductwork size and design assessment.

First, Shorter is always better, and the straighter the better. Finally, Upward for hot air is always the best way to go, and remember, hot air rises, so if you have to choose between a 30’ run with 2 elbows out the side wall or a 40-50’ run straight up with no elbows these will be about the same in static pressure at the exhaust point. Every time you change direction you add a small amount of resistance to the air pressure increasing the needed pressure required to move the air along the length of the total discharge ducting system. Most industry standards for deduction in the length of each elbow or 90-degree change in direction is 10’. So a 20’ run with 3 elbows would be equal to a 50’ straight run.

Your Home is Speaking To You. You need to Listen!

When your windows are sweating you need to listen! Your mechanical ventilation system has failed! or has it? There are many reasons windows can sweat, call our experts for an in-home inspection and learn from our Pros what your home has been trying to tell you. We speak house!

Customer “Kent” living in an older apartment/condo in Seattle. Has an existing 4” Duct that goes up the wall, turns a corner, crosses the ceiling about 15’ then exits the side of the building. The customer wants to know if he can hook up a 600 CFM Range Hood. Should he just switch to Recirculating? The customer cannot afford and does not want to disturb the existing ductwork.

Our suggestion is to connect the range hood to the existing 4” ductwork versus using the Range Hood in the Recirculating settings mode. Here is why, this Range Hood was a 4-speed Vent Hood. On the lowest 2 speeds, 240 CFM and 360 CFM a 4” Duct is large enough. However, on the 3rd and 4th speeds the pressure inside the ductwork would increase and the blower would have to work a little harder to push the air. Yes, if this customer chooses to run this Range Hood on the highest speed every day then the additional air pressure will reduce the usable life of the motor. But in most real-life situations, the range hood can be installed and hooked up to the existing ductwork yet the customer should understand the limitations and the trade-offs of this type of install. Another concern is when the owner sells the home the venting may get called out as a deficiency during the home inspection due to venting pipe size.

Customer “Homles” lives in Bellevue, WA, and is building a new home. He is venting over a 48” Wolf Range and plans to cook all the time. In fact, when he and his wife entertain, they enjoy cooking together and will have the cooktop on for hours. They want to make sure the Range Hood Ductwork is sized correctly during the renovation and he wants the Range Hood Blower motor in the attic of the home. The BTUs for his Cooktop are a Maximum of 77,500 and they plan to use the indoor grill that is part of the cooktop.

A minimum Ductwork Size of 10” in diameter and 12” if the ductwork extends more than 100’. Also, do not forget to include the 10’ deduction for each elbow on the venting run. They will use a 1200 CFM rooftop blower with controls at the range hood. The 10’ size will accommodate every speed except at the highest speed it may require the blower to work a little harder.