Blower Door Testing Randolph MA - Quick Facts
Local energy code in Randolph
- New construction and major renovations in Randolph follow the Massachusetts Stretch Energy Code. IECC Climate Zone 5A.
- Massachusetts has three energy-code levels - base (2021 IECC), Stretch, and Specialized (Opt-In) - and Randolph is on the Stretch Code.
Blower door requirement in Randolph
- New homes in Randolph 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 Randolph 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 Randolph MA
Certified blower door testing in Randolph - 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 Randolph MA
A blower door test is the code-required way to prove how airtight a home in Randolph 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 Randolph
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 Randolph 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.
A tight, tested envelope shrinks the infiltration share of your heating load. That lets the equipment keep up during cold spells, holds rooms at a steadier temperature between cycles, and often lets a designer right-size the heating system rather than oversizing it to cover leakage.
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 Randolph Homes Leak Air
During depressurization the leaks are exaggerated, making them easy to find. In Norfolk 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
- Homes chasing Passive House or net-zero targets
- Additions over 1,000 sq ft that trigger testing
- New single-family homes needing a code compliance test
- Drafty existing homes seeking targeted air sealing
- Certificate-of-occupancy sign-off
Blower Door Testing Randolph MA Facts
Air leakage and heating cost
Uncontrolled air leakage can raise a home's heating and cooling costs by 30% or more, which is why the code treats envelope tightness as a mandatory measure.
Fail and reseal
If a result comes in above target, the leaks are located and sealed and the home is retested - the goal is a documented pass, not a single reading.
Moisture protection
Controlling air movement also controls the moisture that rides with it, protecting insulation and framing from condensation and mold over the life of the home.
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.
Trusted for Blower Door Testing Randolph MA
I had an excellent experience. Friendly, knowledgeable, and very responsive. I will definitely be coming back.
One of the most reliable companies that I've worked with in Somerville, Massachusetts.
Had a pleasure working with Dom. Everything in the building turned out great and air tight for the coming winter.
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
Blower Door Testing in Randolph: What to Expect
Randolph is one of the newest Stretch Code towns in Massachusetts: the state's adoption list shows its Stretch Code taking effect on January 1, 2026. Randolph has not adopted the Specialized (Opt-In) Code. If you are building a new home there, plan on a code-required blower door test with a result of 3.0 ACH50 or lower. Passive House and Phius builds use far tighter targets.
Calling for inspections in Randolph
Randolph's Inspectional Services office is at 41 South Main Street, 2nd floor (781-961-0921). The town says inspection requests are not taken online; the building inspector takes calls on set days (781-961-0922). The blower door test belongs at the end of construction, before the final inspection and the certificate of occupancy, so have the report in hand before you call.
Mid-century houses
Randolph's housing is mostly from the postwar decades. Census data (ACS 2019-2023) shows about half of its homes were built between 1950 and 1979, and about 61% are detached single-family houses. When these houses are taken down to the studs and rebuilt, the usual leaks show up at:
- rim joists and sill plates in the basement,
- attic hatches and recessed lights,
- holes for plumbing, wiring and vents.
New construction can leak in the same places if the air barrier has gaps, which is why many builders ask us for a check before drywall.
Getting ready
Shut windows and outside doors, turn off heating, cooling and ventilation equipment, and fill drain traps. We seal exhaust openings only as the test protocol allows. If the house tests above 3.0 ACH50, we leave the fan running while leaks are sealed and then retest. Randolph is served from our Somerville office at 519 Broadway.
Real blower door tests by HEEC for Randolph 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 Randolph homes.
FAQ About Blower Door Testing Randolph MA
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.
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 is ACH50 converted to CFM?
The code uses Q50 = (conditioned volume x ACH50) / 60. For example, a 2,700 sq ft home with 9 ft ceilings at 2 ACH50 equals about 810 CFM50.
What documentation do I receive?
You receive the measured ACH50 result on a RESNET/HERS-style report suitable for the building department, plus notes on any sealing performed.
Can a blower door test find where my home is drafty?
Yes. Depressurizing the home exaggerates the leaks so a rater can pinpoint exactly where outdoor air is entering, which guides targeted air sealing.
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.
When did Randolph start requiring the Stretch Code?
According to the state’s municipal energy code list, Randolph’s Stretch Code took effect on January 1, 2026. New homes permitted under it need a blower door test showing 3.0 ACH50 or lower before the final inspection.
Can I request a building inspection online in Randolph?
No. Randolph’s Inspectional Services department says inspection requests are not taken online. Call the building inspector at 781-961-0922 during the posted call-in days, and have your blower door report ready before you book the final.
Blower Door Test Requirements for Randolph Projects
Randolph is not on the Specialized Code list. Its Massachusetts Stretch Code (225 CMR 22.00) took effect on January 1, 2026, so new homes follow the Stretch Code. 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 Randolph building department
Sources: 225 CMR 22.00 (2025 edition) and the 2021 IECC sections listed. Randolph is in Norfolk County, served from our Framingham (68 South St) office.
Blower Door Questions from Randolph Builders
What blower door number does a new home in Randolph 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 Randolph?
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 Randolph · HERS rating in Randolph · Stretch Code help in Randolph
Get Started With Blower Door Testing Randolph MA
Book a certified blower door test and get a permit-ready air-tightness report. Call 617-501-6788.
Mass Save®-Listed HERS Rater
U.S. DOE Efficient New HomeTrusted Partner — Verified
ENERGY STAR®Partner
Phius CertifiedPassive House Verifier
ICCMember★★★★★136 Google
Reviews
The Phius Certified Verifier logo is used under license from Phius.
HERS Ratings Across Randolph and Nearby Communities
Home Energy Efficiency Consultants rates new homes, additions, and major renovations throughout Randolph — including Randolph Center, North Randolph, and South Randolph. Every Randolph project is filed with the Town of Randolph 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 Randolph, including Milton, Braintree, Holbrook, Canton, and Stoughton. Our Somerville office at 519 Broadway is the closest of our four Massachusetts locations — see our Somerville office or call (617) 501-6788 to get a Randolph rating on the schedule.
More Massachusetts Towns We Serve
Certified HERS ratings, blower door testing and energy code compliance across all 351 Massachusetts cities and towns.
