Does REScheck Work for Washington State Energy Code Permits?
Why REScheck isn't enough in Washington
REScheck validates the national IECC envelope/UA. Washington amends that code and layers on mandatory R406 energy credits (R401.2 path 1). Passing the IECC UA check does not mean you've met R406, which is the gap that draws correction notices for out-of-state designers.
| REScheck (DOE) | wsec.ai | |
|---|---|---|
| Code basis | National IECC | Washington State Energy Code (WSEC-R 2021) |
| Calculates R406 energy credits | No | Yes |
| Total UA / glazing schedule | IECC UA only | WSEC-R Total UA + glazing |
| Accepted at WA building departments | No (alone) | Produces WSEC-R compliance documentation |
| Platform | Windows/desktop | Cloud — Mac, mobile, PC |
What Washington actually accepts
Per WAC 51-11R-40100 (R401.2), projects comply via one of: (1) the prescriptive path —R402 envelope plus R406 energy credits; (2) the Total UA alternative (R402.1.5); (3) the R405 performance path; or (4) the R407 path. REScheck doesn't satisfy the R406 credits the prescriptive path requires. wsec.ai handles the prescriptive and Total UA paths.
FAQ
Can I use REScheck for a Washington building permit?
Not on its own. REScheck checks the national IECC and does not calculate Washington's required R406 energy credits, so a WA reviewer will typically issue a correction.
REScheck is approved federally — why doesn't it work here?
Washington heavily amends the IECC and adds the R406 credit system. A federally valid IECC check doesn't demonstrate R406 compliance.
I'm an out-of-state designer — what should I use?
Use a Washington-specific path: the prescriptive path with R406 credits (the C3 or wsec.ai), the Total UA alternative, or a WA-supported performance/ERI path.
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