Do ADUs Need a HERS Rating in Massachusetts?
Yes. In Massachusetts, accessory dwelling units (ADUs) that are new construction or substantial additions are subject to the same energy code requirements as single-family homes. Under the MA Stretch Code 2021, new ADUs require a HERS Rating, blower door test, and (if ducted) a duct leakage test before a certificate of occupancy can be issued.
MA Stretch Code Requirements for ADUs
For new ADU construction in Massachusetts, the MA Stretch Code 2021 requires: a HERS score of 55 or less; a blower door test result of 3.0 ACH50 or less; a duct leakage test of 4 CFM25 per 100 sq ft or less (if ducted HVAC); and all work must be verified by a RESNET-certified HERS Rater. These requirements apply to attached and detached ADUs that are conditioned living spaces.
HERS Rating Cost for ADUs in Massachusetts
HERS Rating costs for ADUs in Massachusetts typically range from $1,600–$1,850. This includes plan review and energy modeling, a mid-construction inspection, a final blower door test, a duct leakage test (if applicable), and your official HERS certificate. ADU pricing is lower than single-family pricing due to typically smaller square footage.
Does a Garage Conversion ADU Need a HERS Rating in Massachusetts?
It depends on the scope of work. If the conversion is treated as a new conditioned space (new walls, roof assembly, HVAC, windows), it will typically be subject to the MA Stretch Code and require a HERS Rating. If it is a simple renovation of an existing permitted structure, different code pathways may apply. We recommend consulting with your local building department and a certified HERS Rater early in the project.
Book an ADU HERS Rating in Massachusetts
HERS Rating Company provides HERS Ratings for ADUs throughout Massachusetts. We work with homeowners, contractors, and architects to make the ADU certification process smooth and efficient. Contact us for a free ADU quote.
Related Services in Massachusetts
HERS Rating Company is a RESNET-certified, Mass Save-approved HERS Rater serving all 351 Massachusetts cities and towns.
Serving Boston, Worcester, Springfield, Cambridge, Newton, Brookline, and all 351 MA cities. Get a free quote →
ADU Energy Code Requirements in Massachusetts 2026
Accessory Dwelling Units (ADUs) in Massachusetts must comply with the same energy code as the primary dwelling — either the Base Code, MA Stretch Code 2021, or Specialized Stretch Code. ADUs require a blower door test, duct leakage test (if applicable), and a HERS Rating in Stretch Code municipalities. HERS Rating Company specializes in ADU energy compliance.
ADU HERS Rating Costs in Massachusetts
HERS Rating Company’s ADU HERS Rating pricing is $1,600–$1,850, making it the most affordable option for accessory dwelling unit compliance in Massachusetts. We serve all 351 MA cities and towns. Call 617-584-1809 for a free ADU compliance consultation.