Blower Door Testing Medford MA
Certified blower door testing in Medford - 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 Medford MA
A blower door test is the code-required way to prove how airtight a home in Medford 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, while remodels are allowed up to 5.0 ACH50.
| Project type | Max ACH50 | Notes |
|---|---|---|
| New construction | 3.0 or lower | Mandatory blower-door test under R402.4.1.2 |
| Remodel / alteration | 5.0 | Realistic target for existing assemblies |
| Addition < 1,000 sq ft | Exempt* | May be exempt from testing (R502.3.1) |
| Passive House / Specialized | 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 Medford
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 Medford Cold Spells
Air-leakage heat loss grows with the gap between indoor and outdoor temperature, which is why a drafty home feels worst in a deep freeze. Warm air you have paid to heat escapes high, cold air rushes in low, and the heating system ends up chasing a load that keeps climbing as the temperature drops.
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 Medford Homes Leak Air
During depressurization the leaks are exaggerated, making them easy to find. In Middlesex 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
- Mass Save incentive and rebate projects
- Additions over 1,000 sq ft that trigger testing
- Pre-drywall diagnostic testing for builders
- New single-family homes needing a code compliance test
- Multi-family and townhouse units
Blower Door Testing Medford MA Facts
Small-addition exemption
Additions under 1,000 sq ft can be exempt from air-leakage testing under R502.3.1, though the connected existing home may still benefit from a test.
Ties into ventilation
Because a tight home needs mechanical fresh air, the verified blower-door rate feeds the R403.6 ventilation sizing under ASHRAE 62.2 - air sealing and ventilation are designed together.
Coastal wind exposure
Homes near the coast face steady wind-driven infiltration, so a tight, well-tested envelope pays back faster in exposed and shoreline locations.
When the test happens
The blower door test is typically run near completion, once the air barrier, windows, and penetrations are sealed but while any needed corrections are still easy to make.
Trusted for Blower Door Testing Medford MA
Knowledgeable and professional. Highly recommend them if you want a thorough efficiency assessment.
Five stars isn't enough. The team at Home Energy Efficiency Consultants LLC goes above and beyond every time. They're the gold standard for HERS ratings in Massachusetts.
Great job — thank you so much for your service. They helped me with the HERS ratings and guided me through the building process to help me reach passing scores! Thank you!
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
FAQ About Blower Door Testing Medford MA
Do you work with builders and homeowners?
We work with builders, remodelers, designers, and homeowners - from single tests for permit sign-off to pre-drywall diagnostics that catch problems early.
Will sealing my home cause moisture problems?
No - controlled tightness plus proper ventilation actually reduces moisture problems, because you stop humid air from moving through and condensing inside assemblies.
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.
What happens if my home fails the test?
The rater locates the leaks with smoke, an infrared camera, or by feel, those areas are sealed, and the home is retested until it meets the target.
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.
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.
Get Started With Blower Door Testing Medford MA
Book a certified blower door test and get a permit-ready air-tightness report. Call 617-501-6788.
