Blower Door Testing Duxbury MA - Quick Facts
Local energy code in Duxbury
- Duxbury enforces the Massachusetts Stretch Energy Code for new construction and major renovations. IECC Climate Zone 5A.
- Massachusetts has three energy-code levels - base (2021 IECC), Stretch, and Specialized (Opt-In) - and Duxbury is on the Stretch Code.
Blower door requirement in Duxbury
- New homes in Duxbury must test at 3.0 ACH50 or tighter under the Massachusetts Stretch Code.
- Air-leakage testing is mandatory, measured with a calibrated blower-door fan to the RESNET / ASTM protocol - there is no inspection-only substitute for the result.
- Companion duct leakage limit: 4.0 CFM25 per 100 sq ft of conditioned floor area total leakage (8.0 when all ducts are inside conditioned space - the test is still required).
- Same-day preliminary results; final report in 24-48 hours, filed with the Duxbury building department.
2026 Mass Save incentives in Duxbury
- A tight result unlocks Mass Save all-electric incentives ($7,500 to $25,000 per new single-family home); an all-electric renovation testing at 3.0 ACH50 or better reaches the Level 2 tier, up to $30,000.
- Incentives require a Mass Save-approved, RESNET-certified HERS rater.
RESNET-certified · 15,000+ ratings completed · 5.0 stars across 136 Google reviews · (617) 501-6788
Blower Door Testing Duxbury MA
Certified blower door testing in Duxbury - we measure your home's air-tightness in ACH50, pinpoint leaks, and document a passing result for your building permit.
Air-tightness at a glance
Blower Door Testing Duxbury MA
A blower door test is the code-required way to prove how airtight a home in Duxbury really is. A calibrated fan depressurizes the house to 50 Pascals so we can measure exactly how much air leaks through the envelope, reported as air changes per hour (ACH50). New construction must reach 3.0 ACH50 or lower, and no home on any compliance path may exceed 5.0 ACH50 (IECC 2021 R402.4.1.2).
| Project type | Max ACH50 | Notes |
|---|---|---|
| New construction | 3.0 or lower | Mandatory blower-door test under R402.4.1.2 |
| Maximum on any compliance path | 5.0 | Code cap under IECC 2021 R402.4.1.2 |
| Addition < 1,000 sq ft | Exempt* | May be exempt from testing (R502.3.1) |
| Passive House (PHI; Phius uses 0.06 CFM50/sq ft) | 0.6 | Whole-building test, Phius/PHI protocol |
*Confirm with your local building department. Requirements per the 2025 MA Stretch Energy Code Technical Guidance.
How Blower Door Testing Works in Duxbury
The fan mounts in an exterior doorway and holds the home at a fixed 50-Pascal pressure difference - about what a 20 mph wind would exert. The airflow required to maintain that pressure, in CFM, converts to ACH50 using the home's conditioned volume.
The code converts the result to Q50 (CFM at 50 Pa) with Q50 = (Volume × ACH50) ÷ 60. A 2,700 sq ft home at 2 ACH50 works out to roughly 810 CFM50.
Keeping Heat In During Duxbury Cold Spells
In winter the biggest enemy of a warm home is often invisible air movement. The stack effect drives heated air out through the top of the envelope and draws frigid air in near the floor, robbing heat all season - Cornell extension research describes it plainly as the effect that steals warmth from your home every winter.
Sealing and verifying the envelope with a blower door test blunts that stack effect. You keep more of the heat you have already produced, cold-floor drafts fade, and the furnace or heat pump can actually hold temperature through the coldest stretches instead of running flat out and falling behind.
Lower heating load
Less infiltration means a smaller winter heat-loss load and equipment that can keep up.
Retain paid-for heat
Warm air stays in the living space instead of escaping out the top of the house.
Steadier comfort
Fewer cold-floor drafts and a temperature that holds between heating cycles.
Where Duxbury Homes Leak Air
During depressurization the leaks are exaggerated, making them easy to find. In Plymouth County's older housing stock the usual suspects are rim joists, top plates, attic hatches, recessed lights, and penetrations for plumbing and wiring. Coastal and exposed sites feel wind-driven infiltration most, so a tight, verified envelope pays back quickly here.
Best Fit for Projects Like
- New single-family homes needing a code compliance test
- Mass Save incentive and rebate projects
- Homes chasing Passive House or net-zero targets
- Multi-family and townhouse units
- Additions over 1,000 sq ft that trigger testing
Blower Door Testing Duxbury MA Facts
The reference scale
For perspective, a very leaky older home can exceed 11 ACH50, current code sits at 3.0 for new builds, and certified Passive House projects reach 0.2 to 0.6 ACH50.
New construction target
New residential construction in Massachusetts must test at 3.0 ACH50 or lower. Tighter is better, and many high-performance builders aim well under that number.
Steadier indoor temperature
A tight home holds its heat longer between heating cycles, so rooms stay at a steadier temperature and recover faster after a cold, windy night.
Why 50 Pascals
The 50-Pascal test pressure simulates roughly a 20 mph wind pushing on every surface of the building at once, giving a repeatable, weather-independent leakage number.
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Our Massachusetts Service Locations
Serving clients from our Massachusetts locations in Everett, Somerville, and Framingham.
Everett Location
371 Main St
Everett, MA 02149
Somerville Location
519 Broadway
Somerville, MA 02145
Framingham Location
68 South St
Framingham, MA 01702
Real blower door tests by HEEC for Duxbury projects
These are photos from Home Energy Efficiency Consultants blower door testing jobs in Massachusetts — the same equipment and setup our certified raters bring to Duxbury homes.
FAQ About Blower Door Testing Duxbury MA
What is a blower door test?
It is a diagnostic that measures how airtight a building is. A calibrated fan mounted in a doorway pressurizes or depressurizes the home to 50 Pascals and measures the airflow needed to hold that pressure, which is reported as ACH50.
Is a blower door test required by code?
Yes. Air-leakage testing is mandatory under R402.4.1.2 for new residential construction, verified with a blower door at 50 Pascals.
Does a tighter house need mechanical ventilation?
Yes. A tight home relies on balanced mechanical ventilation for fresh air, and the code sizes that ventilation (R403.6 / ASHRAE 62.2) using your verified blower-door rate.
When in construction should the test be done?
A pre-drywall diagnostic test is ideal for catching leaks while they are easy to reach, followed by a final compliance test near completion.
How does air sealing help during a cold spell?
In winter the stack effect drives warm air out the top of the house and pulls cold air in low down, and it gets stronger the colder it is. A tight, tested envelope blunts that effect, so you retain more of the heat you have paid for and your heating system can keep up during a deep freeze.
How long does a blower door test take?
For a typical single-family home the test itself usually takes well under an hour once the fan is set up and the home is prepared.
Blower Door Test Requirements for Duxbury Projects
Duxbury is not on the Specialized Code list, so new homes follow the Massachusetts Stretch Code (225 CMR 22.00), adopted by 242 communities, or the base code if Duxbury has not adopted it. The testing requirements below come from 225 CMR 22.00 and the 2021 IECC it amends.
| Requirement | Limit | Source |
|---|---|---|
| New home, prescriptive path | 3.0 ACH50 or lower | IECC 2021 R402.4.1.3 (Climate Zone 5, all of Massachusetts) |
| Maximum on any compliance path | 5.0 ACH50 or 0.28 CFM50 per sq ft of enclosure | IECC 2021 R402.4.1.2 |
| Attached homes and apartments tested unit by unit | 0.30 CFM50 per sq ft of unit enclosure (alternative) | IECC 2021 R402.4.1.2 exception |
| Mass Save ENERGY STAR tier | 1.5 ACH50 or lower | Mass Save new construction program |
| Passive House (PHI) | 0.6 ACH50 or lower | Passive House Institute |
| Passive House (Phius) | 0.06 CFM50 per sq ft of enclosure (0.08 for non-combustible 5+ stories) | Phius 2024 Certification Guidebook |
How the house is set up for the test
- Exterior windows and doors closed, with no sealing beyond normal weatherstripping
- Dampers closed but not taped, and interior doors open
- Exterior ventilation openings sealed, heating and cooling turned off, supply and return registers open
- Tested at 50 Pascals per ANSI/RESNET/ICC 380, ASTM E779 or ASTM E1827, with a signed report for the Duxbury building department
Sources: 225 CMR 22.00 (2025 edition) and the 2021 IECC sections listed. Duxbury is in Plymouth County, served from our Framingham (68 South St) office.
Blower Door Questions from Duxbury Builders
What blower door number does a new home in Duxbury need?
On the prescriptive path the 2021 IECC requires 3.0 ACH50 or lower in Massachusetts, and no home on any path may exceed 5.0 ACH50. Homes on the HERS path are tested the same way, and the result goes into the HERS model, so a tighter house earns a lower HERS score.
What is ACH50?
Air changes per hour at 50 Pascals: how many times the home's air volume leaks out each hour while a blower door holds the house at 50 Pa. ACH50 = CFM50 × 60 ÷ conditioned volume.
How are townhouses and apartments tested?
Each dwelling unit can be tested on its own and meet 0.30 CFM50 per square foot of the unit's enclosure, which counts walls, floor and ceiling shared with neighbors. Large buildings may also get a whole-building test.
What gets taped or closed during the test?
Windows and exterior doors are closed, dampers are closed but not sealed, and exterior ventilation openings such as bath fan and ERV/HRV terminations are sealed. Interior doors stay open and the heating and cooling system is off.
When should the blower door test happen?
The code test happens at the end of construction. We recommend a pre-drywall test once the air barrier is complete, when leaks are cheap to find and fix, so the final test is a formality.
How much does blower door testing cost in Duxbury?
Pricing depends on the size of the building and the number of units. Send your plans or address and we will quote the test, or bundle it with your HERS rating and duct test in one visit.
Related: Duct leakage testing in Duxbury · HERS rating in Duxbury · Stretch Code help in Duxbury
Get Started With Blower Door Testing Duxbury MA
Book a certified blower door test and get a permit-ready air-tightness report. Call 617-501-6788.
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HERS Ratings in Duxbury, Massachusetts
Home Energy Efficiency Consultants provides Duxbury with certified HERS ratings, blower door and duct leakage testing, and Massachusetts energy-code compliance for new construction, additions, and major renovations — with same-day preliminary reports.
We rate homes across the Commonwealth from our four offices. Reach the one nearest your Duxbury project — Somerville, Framingham, Marlborough, or Everett — or call (617) 501-6788 to schedule a Duxbury rating.
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