Blower Door Testing Eastham MA - Quick Facts
Local energy code in Eastham
- Eastham has been an Opt-In (Specialized Code) community since January 1, 2025, layering electrification requirements on the Stretch Code; it sits in IECC Climate Zone 5A.
- Beyond the Stretch baseline, new mixed-fuel homes must be pre-wired for future electrification and add on-site solar where there is significant unshaded roof space.
- All-electric new homes must use heat pumps for space heating and hot water; fossil-fuel homes over 4,000 sq ft must reach net-zero (HERS 0), and new multifamily over 12,000 sq ft must meet Passive House.
Blower door requirement in Eastham
- New homes in Eastham must test at 3.0 ACH50 or tighter under the Massachusetts Stretch Code (Specialized Code town).
- 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 Eastham building department.
What you can get back: 2026 Mass Save
- 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 Eastham MA
Certified blower door testing in Eastham - 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 Eastham MA
A blower door test is the code-required way to prove how airtight a home in Eastham 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 Eastham
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 Eastham Cold Spells
During a New England cold snap the stack effect goes to work: warm indoor air rises and slips out near the top of the house, and that pulls cold outdoor air in through gaps down low. The colder it gets, the harder this effect pushes - so a leaky home loses the most heat exactly when it can least afford to.
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 Eastham Homes Leak Air
During depressurization the leaks are exaggerated, making them easy to find. In Barnstable 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
- Certificate-of-occupancy sign-off
- Additions over 1,000 sq ft that trigger testing
- Pre-drywall diagnostic testing for builders
- Custom and high-performance builds
- Homes chasing Passive House or net-zero targets
Blower Door Testing Eastham 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.
Retaining the heat you paid for
A tight, tested envelope keeps the warm air you have already paid to heat inside the living space rather than letting it leak out the top of the house.
Quiet, fast, non-destructive
A typical single-family blower door test is non-destructive and usually wraps up in well under an hour once setup is complete.
Helping heat keep up
Sealing the envelope shrinks the infiltration portion of the heating load, so the furnace or heat pump can actually hold temperature through a cold spell instead of running flat-out and falling behind.
Trusted for Blower Door Testing Eastham MA
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This company does all my inspections. I use this company a lot and highly recommend them.
One of the most reliable HERS rating companies I have dealt with in Massachusetts.
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 Eastham 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 Eastham homes.
FAQ About Blower Door Testing Eastham 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.
Do additions need a blower door test?
Many do, but additions under 1,000 square feet can be exempt from air-leakage testing under R502.3.1. We can confirm what your specific project requires.
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.
What ACH50 does new construction need to pass?
New residential construction in Massachusetts must measure 3.0 ACH50 or lower. Many high-performance homes come in well below that figure.
Blower Door Test Requirements for Eastham Projects
Eastham is one of the 60 Massachusetts communities on the Specialized (Opt-In) Code. New homes there are built on the same 225 CMR 22.00 testing requirements below, plus net-zero-ready provisions.
| 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 Eastham building department
Sources: 225 CMR 22.00 (2025 edition) and the 2021 IECC sections listed. Eastham is in Barnstable County, served from our Framingham (68 South St) office.
Blower Door Questions from Eastham Builders
What blower door number does a new home in Eastham 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 Eastham?
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 Eastham · HERS rating in Eastham · Stretch Code help in Eastham
Get Started With Blower Door Testing Eastham 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 Across Eastham and Nearby Communities
Home Energy Efficiency Consultants rates new homes, additions, and major renovations throughout Eastham — including Eastham Center, and North Eastham. Every Eastham project is filed with the Town of Eastham Building Department, and we handle the energy model, blower door and duct leakage testing, and the compliance paperwork from start to finish.
We also serve the communities right around Eastham, including Orleans, Wellfleet, Brewster, Truro, and Chatham. Our Framingham office at 68 South St is the closest of our four Massachusetts locations — see our Framingham office or call (617) 501-6788 to get a Eastham rating on the schedule.
Eastham Specialized Energy Code — HERS Index Targets
Eastham enforces the Massachusetts Specialized (Opt-In) Energy Code. The required HERS score depends on fuel type and project scope — a lower index is stricter.
| Project type | Mixed-fuel | Mixed-fuel + solar | All-electric | All-electric + solar |
|---|---|---|---|---|
| New construction | HERS 42 | 42 | 45 | 45 |
| New construction — embodied-carbon credit | 45 | 45 | 48 | 48 |
| Accessory dwelling unit (ADU) | 52 | 55 | 55 | 58 |
| Major alteration / renovation / change of use | 65 | 70 | 70 | 75 |
A HERS rating is triggered by new construction, additions over 1,000 sq ft (or more than 100% of the existing conditioned area), and Level 3 alterations over 1,000 sq ft affecting more than 50% of the home. New homes must also pass a blower-door test at 3.0 ACH50 and include electrification-ready wiring for heat pumps, EV charging, and solar. We model your Eastham project up front so you know the exact target and the fastest path to hit it — call (617) 501-6788.
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