MA Stretch Code 2026: Complete Builder Guide

Published: May 2026 | MA Stretch CodeBuildersEnergy Code

If you’re building new residential construction in Massachusetts, you’ve probably heard about the MA Stretch Code. In this complete guide, we explain exactly what it requires, which municipalities have adopted it, and what you need to do to comply.

What Is the MA Stretch Code?

The Massachusetts Stretch Energy Code is an optional — but widely adopted — addition to the base Massachusetts energy code (IECC 2021). It sets more stringent energy efficiency requirements for new residential and commercial construction than the base code.

The Stretch Code is administered by the Massachusetts Department of Energy Resources (DOER) and is required in any municipality that has adopted it. As of 2026, over 300 Massachusetts cities and towns require Stretch Code compliance for new construction.

MA Stretch Code Requirements at a Glance

The Three Core Tests Required

1. HERS Rating (HERS Index Score ≤ 55)

A RESNET-certified HERS Rater must evaluate the home using energy modeling software and assign a HERS Index score. The score must be 55 or below. The average new home built to code scores around 100; a HERS 55 home uses roughly 45% less energy than average.

2. Blower Door Test (≤ 3.0 ACH50)

A blower door test measures how airtight the home’s building envelope is. Under the MA Stretch Code, new residential construction must achieve 3.0 ACH50 or less. The test is typically performed after drywall is installed but before final finishes.

3. Duct Leakage Test

Using a duct blaster device, the rater measures how much conditioned air escapes through duct leaks. Leaky ducts can waste 20–30% of heating and cooling energy. The Stretch Code requires duct systems to meet specific leakage limits.

Does My City Require the Stretch Code?

Over 300 Massachusetts municipalities have adopted the Stretch Code, including Boston, Cambridge, Newton, Framingham, Worcester, Springfield, Lowell, Quincy, and most other cities and larger towns. Check with your local building department to confirm requirements for your specific project.

When Must You Comply?

Stretch Code compliance is required for:

• New residential construction (single-family, multifamily, ADUs)
• Major renovations that trigger energy code review
• Projects seeking building permits in Stretch Code municipalities

How Does the Process Work?

Working with a RESNET-certified HERS Rater for full Stretch Code compliance typically follows this process:

• Plans Review: Before construction, your rater reviews plans and creates an energy model to verify the design will meet HERS 55.
• Construction Inspection: During construction, the rater verifies insulation, windows, and HVAC match the model.
• Blower Door Test: After drywall, the rater performs the blower door test.
• Duct Leakage Test: Before HVAC final, the duct system is tested.
• Certified Report: You receive a certified compliance package for your building department within 24 hours.