There are three levels of building energy codes in Massachusetts:
- The Base Code is IECC 2021 with MA amendments: 780 CMR Chapter 11R (residential) and 780 CMR Chapter 13 (commercial). The 780 CMR 10th Edition is the current building code for Massachusetts.
- The opt-in Stretch Code is IECC 2021 with key MA amendments: 225 CMR Chapter 22 (residential) and 225 CMR Chapter 23 (commercial).
- The opt-in Specialized Code is IECC 2021 key MA amendments: 225 CMR Chapter 22 + Appendix RC (residential) and 225 CMR Chapter 23 + Appendix CC (commercial).
This map shows which level of code is followed by each municipality.
The tenth edition building code became effective on October 11, 2024 with a concurrency period, during which either the ninth or tenth edition building codes could be utilized. This concurrency period, which was extended, ends June 30, 2025, at which time the tenth edition will be the only building code in effect.
Links to Code Documents
The latest version of the Stretch and Specialized Codes as of February 14, 2025
Stretch & Specialized Code - Residential
Stretch & Specialized Code - Commercial
780 CMR 10th Edition (MA Building Code)
2026 Public Comment
DOER is pleased to release a series of proposed revisions to the Stretch and Specialized codes, covering both commercial and residential sections. Based on the feedback received over the last year, these modest revisions are now available for public comment.
The revisions to the Stretch and Specialized codes are presented here, in both clean and redline versions, along with a summary of the proposed changes:
Stretch & Specialized Commercial Proposed (red lines)
Stretch & Specialized Residential Proposed (red lines)
Stretch & Specialized Commercial Proposed (clean version)
Stretch & Specialized Residential Proposed (clean version)
Stretch + Specialized updates explainer 02/03/2026
DOER is seeking public comment on these documents. There will be a Public Hearing on June 16, 2026, 2 - 4 PM, zoom: ZOOM Register Link . Translation services available upon request.
Written comments will be accepted until 5 PM EST on June 24, 2026. Please submit written comments on the proposed revisions electronically to stretchcode@mass.gov with the words "Stretch Code Public Comment" in the subject line. Alternatively, comments can be submitted via mail to Becca Edson, Department of Energy Resources, 100 Cambridge Street, 9th floor, Boston, MA 02114.
District Energy Systems Guidelines
On June 24, 2025, DOER released its draft “Guideline on District Energy Systems” for public comment. DOER accepted public comments on the draft guideline until July 15, 2025. The guideline provides details on how to qualify district energy systems that are decarbonizing for relief from certain electrification requirements in the Massachusetts Energy Code.
Draft Guidelines for District Energy Systems, June 2025
Public Comments Received on Draft Guidelines for District Energy Systems
2025 Stretch Code Updates Webinar
Technical Documents
Stretch Code Technical Guidance Updated 9/30/2025
Attachment A: Envelope Performance and Thermal Bridge Derating
Attachment B: ASHRAE Appendix G Relative Performance Simulation Guidelines
Attachment C: Targeted Performance Simulation Guidelines
Attachment D: District Energy System Guidelines
Attachment E: Embodied Carbon Insulation Calculator
Attachment F: Low-Carbon Concrete Mixes available in MA
Additional Resources
Contact
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| Date published: | November 27, 2024 |
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