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2009 Washington State Energy Code

Our code experts provide support to those who use the residential sections of the Washington State Energy Code (WSEC). The 2009 code went into effect January 1, 2011 (visit the State Building Code Council website for updates).

Have questions about the residential code?
Email or call the WSEC Residential Code Hotline at (360) 956-2042. Other resources to help you are:

Code Text
Compliance Publications & Help
Prescriptive Worksheets
Scheduled Trainings
List of Duct Testers
Presentations & Videos
Hot Topics

We also offer resources for the 2012 Washington State Energy Code. For non-residential code resources, contact the Northwest Energy Efficiency Council.


Sign up to receive email updates about energy code changes and educational opportunities from the Energy Code listserv.

Code Text

We provide support regarding the residential code only.

2009 WSEC - Chapters 1 through 10 (Single-Family Residential)

2009 WSEC - Chapters 11 through 15 (Multi-Family and Non Residential)


2012 Washington State Energy Code – Residential

2012 Washington State Energy Code – Commercial

2012 Washington State Energy Code – Appendices

*The 2012 Washington State Energy Code will take effect on July 1, 2013

Compliance Publications & Help

These resources pertain to the residential sections of the 2009 WSEC.

Builder's Field Guide

To view the 2006 version, see 2006 Edition of the Builder's Field Guide.

Other Publications

Prescriptive Worksheets

  • Prescriptive Method (2009 WSEC Chapter 6). The prescriptive approach is the simplest method of WSEC code compliance. Meet all the minimum insulation levels required by one of the options, choose an additional credit and the project complies with the building envelope. The following Excel files provide a method for documenting compliance with the prescriptive standards. The files are for single-family and duplex construction as defined by the International Residential Code (IRC). Choose either Prescriptive Climate Zone1 or Prescriptive Climate Zone2 depending on location of the building.
  • Prescriptive Worksheet Training The Prescriptive Zone 1 Worksheet Training is a narrated, step-by-step document that provides assistance when filling out the Prescriptive Zone 1 Worksheet. Please note, you must have Adobe Reader 9.0 or later to view this file.
  • Component Performance Approach (2009 WSEC). The CPWorksheet is designed to document the qualification of building designs by the component performance approach described in Chapter 5 of the WSEC.
  • 2009 Additions Worksheet The additions worksheet can be used for additions less than 750 square feet that do not fully comply with WSEC requirements. Energy improvements made to the existing home can used to compensate for energy deficiencies in the addition. A Component Performance worksheet must be filled out to determine the UA deficiency of the addition prior to completing the additions worksheet. Download 2009 Additions Worksheet

Scheduled Trainings

The WSU Extension Energy Program offers training on the residential sections of the 2009 WSEC and on duct testing protocols. Training details and schedule.

List of Duct Testers

We have compiled a list of individuals who have attended the one-day Duct Testing Training offered by the WSU Extension Energy Program and meet the minimum requirements to test ducts for the 2009 Washington State Energy Code.

Technicians who can verify that they have successfully completed duct testing training provided by the Northwest ENERGY STAR Program or from Performance Tested Comfort Systems (PTCS) may also be qualified to test ducts under the 2009 Washington State Energy Code (WSEC). For a database of PTCS technicians, refer to: For a database of Northwest ENERGY STAR verifiers, refer to:

Presentations and Videos

Duct Sealing Video

"Duct Sealing for Comfort, Energy and Indoor Air Quality" (16:45 min.)

Air Leakage In Homes: The Invisible Thief

Our air sealing video is divided into seven chapters so that you may choose to view all of the chapters or only those that are specific to your needs.

Washington State Energy Code Presentations

Although these trainings are frequently modified to meet jurisdictional needs and improve quality, here is what you will see or what you saw at a WSU Extension Energy Program residential energy code training.

"Hot Topic" Archives


Click on the question to show or hide the answer

Support and Training

Q: I have a Washington State Energy Code (WSEC) question – who do I contact?
WSU Extension Energy Program is funded to provide technical assistance on the single family residential sections of the WSEC, Chapters 1-10.

Phone: 360-956-2042
Contact: Gary Nordeen, Luke Howard, Emily Salzberg and Tanya Beavers

The Northwest Energy Efficiency Council (NEEC) provides technical assistance on the non-single family residential and commercial sections of the WSEC.

Phone: 206-624-0283
Q: I would like to attend an Energy Code class, how do I find out more information?
A: WSU is currently offering two courses on the residential sections of the 2009 WSEC; 2009 WSEC Overview of Changes and Duct Testing and Sealing for 2009 WSEC Compliance. From our website, you can view upcoming trainings by clicking on the “Events and Trainings” link. Online registration is available for classes that are posted. If you do not see a class time or location that works for you, you may sign up for the email Listserv which will notify you of trainings as they are scheduled.

Compliance Forms

Q: Where do I find WSU’s compliance forms for the WSEC?
A: WSU's 2009 WSEC compliance worksheets are available on our website under “Compliance Publications and Help”:

The Prescriptive Worksheet contains the General Compliance page, Glazing Schedule and Heating System Sizing Calculator. You will need to choose the correct worksheet based on which climate zone the project is in (zone 1 or zone 2).

If you are complying with the energy code by Component Performance (chapter 5), you can download the CP Worksheet from our website as well. This worksheet can be used for both zone 1 and 2.

The Additions Worksheet is also available in the same section of this webpage. The additions worksheet can be used for additions less than 750 square feet that do not fully comply with WSEC requirements. Energy improvements made to the existing home can used to compensate for energy deficiencies in the addition. A Component Performance worksheet must be filled out to determine the UA deficiency of the addition prior to completing the additions worksheet.
Q: Why don’t I have tabs for the different worksheets or I only see the copyright page?
A: When you open the file, if the tabs at the bottom of the file are not visible, click on the “maximize” icon in the upper right portion of the Excel file (this is the square between the “X” and the “-“ )
Q: What if I don’t have a current version of Microsoft Office and am unable to view or download the forms?
A: WSU’s compliance worksheets were developed using Microsoft Excel 2007. If you have an earlier version of Excel and are having issues using the spreadsheets, we recommend that you try downloading the Microsoft Compatibility Pack at:

Microsoft states that this Compatibility Pack will allow users with earlier versions of Microsoft Office to use documents that are developed in the new versions of the software.
Q: I need help filling out compliance forms, how do I get more information?
WSU has a narrated PowerPoint presentation available which explains how to fill out the Prescriptive worksheets. You will find this presentation on our website. If you need additional assistance, you may contact us at or 360-956-2042.

Duct and Blower Door Testing

Q: Do you have to be certified to perform blower door testing?
A: No. At this time, the 2009 WSEC does not require a certification to perform an air leakage test on a house. We highly recommend that air leakage testing personnel attend the one day duct and air leakage class to make sure that they are aware of the maximum allowed leakage rates, test pressures and proper set-up of the testing equipment.
Q: Testing of the envelope is now required for an addition if that addition is more than 750 sq. ft. Does one test the whole house when over that 750 limit? What if the addition is attached to a 50 year old leaky house? Would the owner then have the option of isolating the new portion from the old?
A: Only the addition needs to be tested – not the entire house. This is done by isolating the addition from the existing house and then testing the addition only.

Energy Code Requirements

Q: Where can I find a copy of a previous energy code? My house was built in 19XX, what were the energy code requirements then?
A: Depending on how the home originally complied with the energy code, the prescriptive requirements of the WSEC may or may not apply. Homes may have used component performance or systems analysis as a means to comply with the code. Systems analysis was used far more frequently in the 1990’s than it is used now.

Also, the appropriate code version is determined by the date on which a building department received a complete permit application, not the date of construction. If a house was built in XXXX year, the permit could have been issued under a previous code version.

Download copies of previous energy codes
Q: I noticed that the description of an Intermediate Framed Wall in Chapter 10 of the Washington State Energy Code states, “Headers consist of double 2x material with R 10 insulation between the header and exterior sheathing.” Does this mean that I can’t use a solid 4x header and is the foam insulation required to be installed on the exterior side of the header?
A: From a thermal standpoint it does not matter if the foam is installed on the exterior, interior or between two 2x headers (referred to as a sandwich header). 4x header material is allowed and foam can be installed on the interior or exterior surface of the header.
Q: If a 6x header is required to be installed in a 2x6 wall for structural loading purposes, how do you insulate the header?
A: If a 6x header is required for loading purposes in a 2x6 wall, there is no space to install R-10 foam sheathing and it is not required. The structural requirements of the IRC supersede the Washington State Energy Code requirements.
Q: How do I know what Climate Zone my project is located in?
A: Climate Zones in Washington are listed by county in Chapter 3 of the Washington State Energy Code. Here is a map of climate zones.
Q: What is systems analysis and how do I use it to comply with the energy code? Do I need a Chapter 9 credit?
A: Systems analysis is outlined in Ch. 4 of the WSEC and requires calculating an annual energy budget using computer software. A code compliant “target” house is first modeled to calculate the annual energy use of the house if it was built to minimum code requirements. The house, as designed, is then modeled. This is referred to as the “proposed” house. The proposed house must be 8% more efficient than the target house. Using this compliance approach, no additional credits are needed from Chapter 9, as would be required when using either the Prescriptive or Component Performance methods. The 8% efficiency increase requirement accounts for the Chapter 9 credit.

Unlike component performance which only allows trade-offs of the building envelope components, systems analysis evaluates the impact of such items as solar orientation, high efficiency mechanical systems, thermal mass qualities, renewable energy systems, etc.

Chapter 8 of the WSEC lists suggested software for systems analysis. You may want to confirm with the local building department if you are using software that is not on the list of suggested software. If you plan on documenting compliance with systems analysis, you will need to follow the procedure and design criteria outlined in Chapter 4 of the WSEC.
Q: I need R-24 insulation in exterior walls for Climate Zone 2. My exterior walls are 2x6 construction. What are economical and efficient options to achieve R-24 with 2x6 wall construction?
A: There are some high density insulation products on the market that can have a nominal R-value of 24 when installed in a 2x6 cavity. To achieve an R-value of 24 the product must be installed in accordance with the installed density specifications. Also, it is important to verify is that the product’s R-value has been tested in accordance with ASTM standards (C 518) as required by the Federal Trade Commission.

Spray foam is another option. R-values of closed cell spray foams typically range from R 5.6 – 7.3 per inch. Closed cell foam can be expensive to install so some builders are choosing to go with a hybrid system. A hybrid system is a combination of closed cell foam that does not fill the entire framing cavity. The rest of the cavity is filled with an insulation batt or another type of insulation product. This is commonly called a “flash and batt” system. Important to be aware of is that closed cell foam is also typically a vapor retarder when installed at 2” depth. The WSEC specifies that the vapor retarder must be installed on the warm side of insulation (in winter) or be installed with no more than 1/3 of the nominal R-value between it and the conditioned space. Please see section 502.1.6.1, Vapor retarders, for more details.

R-5 rigid foam installed on the exterior of a building with R-19 cavity insulation is another approach. There are increasing numbers of builders choosing to insulate in this way because it can help mitigate issues with moisture and dew point inside a wall cavity. Adding rigid insulation to the exterior of a building can help to bring dew point outside of the exterior sheathing so when moisture gets into a wall assembly in vapor form it will be less likely that the exterior sheathing will be a condensing surface.

Component performance (outlined in Ch. 5 of the WSEC) may be another option to look into. Component performance allows you to make tradeoffs in efficiency within the building envelope. So in other words, you can potentially build a wall that does not meet the prescriptive R-value requirements but you need to make up for this elsewhere (e.g. blowing more insulation in the attic, increasing the efficiency of windows, etc.) WSU has a CP worksheet that is designed to document component performance compliance with the 2009 WSEC. The CP worksheet compares a code target house (based on table 5-1) to your proposed house. Keep in mind though that you would still need a credit from Ch. 9.