What Is a Blower Door Test?
A blower door test is a diagnostic procedure that measures how airtight your home is. A certified HERS Rater mounts a calibrated fan in an exterior doorway, depressurizes the building to 50 Pascals, and measures how much air leaks through the building envelope. The result is expressed as ACH50 (air changes per hour at 50 Pascals).
Is a Blower Door Test Required in Massachusetts?
Yes. Under the MA Stretch Code 2021 (adopted from IECC 2021), all new residential construction in Massachusetts must pass a blower door test before receiving a certificate of occupancy. The test must be performed by a RESNET-certified HERS Rater. Most Massachusetts cities and towns have adopted the Stretch Code, making this a near-universal requirement for new construction statewide.
What Is a Passing Blower Door Test Result in Massachusetts?
Under the MA Stretch Code 2021, new homes must achieve 3.0 ACH50 or less. High-performance homes often achieve 1.0–2.0 ACH50. For reference, older homes typically test at 10–20 ACH50. The lower your ACH50 score, the more airtight your home is.
| Performance Level | ACH50 Result |
|---|---|
| MA Stretch Code Minimum | 3.0 ACH50 or less |
| Good Performance | 1.5–2.9 ACH50 |
| High Performance / Near Zero | Below 1.0 ACH50 |
| Typical Older Home | 10–20 ACH50 |
How Much Does a Blower Door Test Cost in Massachusetts?
Blower door testing in Massachusetts typically costs $350–$600 for a single-family home. The cost is usually included as part of a full HERS Rating package, which ranges from $1,850–$2,500 and includes plan review, energy modeling, mid-construction inspection, blower door test, and duct leakage test.
How to Prepare Your Home for a Blower Door Test
To prepare for your blower door test in Massachusetts: close all windows and exterior doors; ensure all intentional openings (fireplace dampers, ventilation inlets) are temporarily sealed per ASHRAE 402.4.1.2; make sure the HVAC system is installed and accessible; ensure the home is in a “ready to test” condition per your HERS Rater’s instructions. Common failure points include recessed lighting, electrical outlets on exterior walls, attic hatches, and rim joists.
What Happens If You Fail the Blower Door Test?
If your home fails the blower door test (i.e., exceeds 3.0 ACH50), you will need to identify and seal the air leakage sources and retest. Your HERS Rater can help you identify likely problem areas. Common fixes include additional caulking, weatherstripping, spray foam at penetrations, and improved window installation. We offer re-tests as part of our Massachusetts blower door testing services.
Book a Blower Door Test in Massachusetts
HERS Rating Company is a RESNET-certified HERS Rater serving all of Massachusetts. We provide blower door testing for new construction throughout the state, including Boston, Worcester, Springfield, Cambridge, and all surrounding communities. Contact us for a free quote.
Related Services in Massachusetts
HERS Rating Company is a RESNET-certified, Mass Save-approved HERS Rater serving all 351 Massachusetts cities and towns.
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