Duct Leakage Testing Attleboro MA - Quick Facts
Local energy code in Attleboro
- New construction and major renovations in Attleboro 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 Attleboro is on the Stretch Code.
Duct leakage requirement in Attleboro
- Attleboro permits under the Massachusetts Stretch Code cap duct leakage at 4 CFM25 per 100 sq ft of conditioned floor area.
- Testing is required unless the entire duct system and air handler sit inside conditioned space; a rough-in test and a final test may both apply.
- Results in 24-48 hours with clear pass/fail documentation, filed with the Attleboro building department.
- From $350 for the first ducted system, often bundled with blower door testing and a full HERS rating.
What you can get back: 2026 Mass Save
- Duct and blower door results feed the HERS rating that unlocks Mass Save all-electric incentives: $7,500 to $25,000 per new single-family home and $1,000 to $3,750 per multifamily unit.
- Incentives require a Mass Save-approved, RESNET-certified HERS rater.
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Duct Leakage Testing Attleboro MA
Professional duct blaster testing across Attleboro and Bristol County, verifying your ductwork meets the Massachusetts code limit.
Duct Leakage Requirements in Attleboro
Attleboro follows the Massachusetts Stretch Code, which caps total duct leakage at 4 CFM25 per 100 square feet. Our raters measure your ductwork in CFM25 and document a clear pass against the 4 CFM25 per 100 sq ft limit.
| Project / code tier | Duct leakage limit | What is tested |
|---|---|---|
| Base energy code | 4.0 CFM25 / 100 sq ft | Total leakage (ducts outside conditioned space) |
| Stretch Code | 4 CFM25 / 100 sq ft (total) | Total leakage (leakage to outside is not a code option) |
| Rough-in test, air handler not installed | 3.0 CFM25 / 100 sq ft | Total leakage (Stretch and Specialized) |
| Ducts fully inside envelope | 8.0 CFM25 / 100 sq ft (test still required) | Air handler + ducts in conditioned space |
IECC Duct Leakage Thresholds Reference
Beyond the Massachusetts tier that applies in Attleboro, these are the federal IECC duct-leakage limits across code editions. All values are CFM at 25 Pascals (CFM25) per 100 sq ft of conditioned floor area (CFA) unless noted.
2009 IECC
| Test stage | Measurement | Leakage limit |
|---|---|---|
| Postconstruction Leakage Test | Duct Leakage to Outdoors | ≤ 8 CFM25 / 100 sq ft CFA |
| Rough-in with AHU | Total Duct Leakage | ≤ 6 CFM25 / 100 sq ft CFA |
| Rough-in without AHU | Total Duct Leakage | ≤ 4 CFM25 / 100 sq ft CFA |
2012, 2015, 2018 & 2021 IECC — Prescriptive Paths
| Test stage | Measurement | Leakage limit |
|---|---|---|
| Postconstruction Leakage Test | Total Duct Leakage | ≤ 4 CFM25 / 100 sq ft CFA |
| Rough-in with AHU | Total Duct Leakage | ≤ 4 CFM25 / 100 sq ft CFA |
| Rough-in without AHU | Total Duct Leakage | ≤ 3 CFM25 / 100 sq ft CFA |
2015 & 2018 IECC — Performance Path (Cost Compliance)
Leakage testing is required unless all ducts and air handlers are located entirely within the thermal envelope. There is no pass/fail threshold for duct leakage on the performance path.
2024 IECC — Prescriptive Path
| Conditioned floor area | Condition at test | Total leakage limit |
|---|---|---|
| >1,000 sq ft CFA | Space-conditioning equipment not installed | < 3 return grilles: ≤ 3 CFM · 3+ return grilles: ≤ 4 CFM |
| >1,000 sq ft CFA | All components installed | < 3 return grilles: ≤ 4 CFM · 3+ return grilles: ≤ 6 CFM |
| >1,000 sq ft CFA | Equipment not installed, ducts entirely in conditioned space | < 3 return grilles: ≤ 6 CFM · 3+ return grilles: ≤ 8 CFM |
| >1,000 sq ft CFA | All components entirely in conditioned space | < 3 return grilles: ≤ 8 CFM · 3+ return grilles: ≤ 12 CFM |
| ≤1,000 sq ft CFA | Equipment not installed | ≤ 30 CFM |
| ≤1,000 sq ft CFA | All components installed | ≤ 40 CFM |
| ≤1,000 sq ft CFA | Equipment not installed, ductwork entirely in conditioned space | ≤ 60 CFM |
| ≤1,000 sq ft CFA | All components entirely in conditioned space | ≤ 80 CFM |
How Duct Leakage Testing Works in Attleboro
A duct blaster seals off your HVAC system and pressurizes it to 25 Pascals. The airflow needed to hold that pressure is your leakage rate in CFM25 — the lower the number, the tighter the ducts.
Common Sources of Duct Leakage We Check in Attleboro
Most duct leakage comes from a short list of predictable weak points. Knowing where to look is what turns a CFM25 number into a fixable list of locations.
Boot & register connections
The joint where a duct boot meets the drywall is the single most common leak point — often left unsealed behind the register grille.
Plenum & air-handler seams
Sheet-metal plenums and the cabinet of the air handler leak at seams and access panels unless mastic-sealed.
Disconnected flex runs
Flexible ducts can pull loose at collars or get crushed above insulation, dumping conditioned air into the attic.
Panned-joist returns
Return cavities framed from floor joists or wall studs are notoriously leaky and can draw in unconditioned air.
Building-cavity returns
Using framing cavities as return ducts pulls air from attics, garages, or crawlspaces instead of living space.
Trunk-line joints
Long supply trunks flex and separate at joints over time, especially where they were only taped rather than sealed with mastic.
Why Tight Ducts Keep Heat In Your Attleboro Home
In Attleboro, leaky ducts quietly waste a large share of what your furnace or heat pump produces, sending warm or cool air into spaces no one lives in.
Once the ducts test tight, the heat you pay for stays in the living space, the system cycles less, and utility bills settle down.
What Your Attleboro Duct Test Report Includes
You get a document your building department and HERS software will accept the first time — not just a number.
- ✓A punch list of leak locations if a re-seal and retest is needed
- ✓Measured total duct leakage in CFM at 25 Pascals (CFM25)
- ✓Leakage normalized per 100 sq ft of conditioned floor area
- ✓Clear pass/fail against the 4.0 CFM25 limit that applies in Attleboro
- ✓The test method used (rough-in or post-construction) per ANSI/RESNET/ICC 380
- ✓Documentation formatted for your HERS rating and building-permit file
Best Fit for Projects Like
- Retest visits after sealing failing seams and boots to confirm compliance
- Additions in Attleboro where new HVAC ducts must comply with Section R403
- Builders who need a fast, permit-ready duct test scheduled around drywall
- Custom homes with complex duct runs that need verification before final inspection
- Attleboro projects that need both envelope air-tightness and duct testing documented in one visit
Duct Leakage Testing Attleboro MA Facts
- The ENERGY STAR savings model assumes a typical unsealed home leaks about 23% of its total system airflow before duct sealing.
- Duct leakage is one of the biggest single variables a HERS Rater can influence on a home's final energy score.
- For a total duct leakage test, a window or door is left open to outside so the test fan measures the ducts alone and not the house.
- Ducts that leak about 20 percent of their conditioned air can force an HVAC system to work roughly 50 percent harder.
Trusted for Duct Leakage Testing Attleboro MA
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
Duct Leakage Testing for Attleboro Homes
Attleboro adopted the Massachusetts Stretch Code effective January 1, 2020, and it is not on the Specialized (Opt-In) Code list. If you are building or gut-renovating in Attleboro, here are the questions we hear most about the duct test, answered for your project.
Which systems get tested?
Every ducted system: a furnace, a central air handler, or a ducted heat pump. Each one gets its own total duct leakage test.
What number do I need?
4.0 CFM25 or less per 100 sq ft of conditioned floor area. If all ducts and the air handler are inside conditioned space, the limit is 8.0 CFM25 per 100 sq ft. The test is still required in that case, and that is a common surprise for builders.
When do you test?
Twice is best. At rough-in we test before insulation and drywall, so any leak is a quick mastic fix. At final we test the finished system, and that result goes into the HERS rating and the energy-code file.
Where do ducts fail?
The usual suspects are register boots not sealed to the drywall, flex duct pulled off a collar in the attic, unsealed basement trunk seams and panned returns, and air handler access panels. Ducts in an attic or unconditioned basement cost the most when they leak, because the lost air leaves the house.
Why does it matter with a heat pump?
Heat pumps rely on steady airflow at a lower supply temperature. Leaky ducts mean weak registers, cool rooms on cold mornings, more run time, and a higher HERS score.
Attleboro's Building Inspections office is at 77 Park Street (508-223-2222 ext. 3251). Permits are filed through PermitEyes, and inspections are scheduled through your PermitEyes account or by phone with at least 24 hours' notice. The city asks that inspection requests not be emailed. Electricity is delivered by National Grid and gas by Eversource. Our nearest office is in Framingham at 68 South St.
Real duct leakage tests by HEEC for Attleboro projects
These are photos from Home Energy Efficiency Consultants duct leakage testing jobs in Massachusetts — the same equipment and setup our certified raters bring to Attleboro homes.
Duct Leakage Testing Attleboro MA FAQ
Duct Leakage Test Requirements for Attleboro Projects
Attleboro adopted the Massachusetts Stretch Code (225 CMR 22.00) effective January 1, 2020 and is not on the Specialized (Opt-In) Code list. The testing requirements below come from 225 CMR 22.00 and the 2021 IECC it amends.
| Test | Limit (CFM25 per 100 sq ft of conditioned floor area) | Notes |
|---|---|---|
| Rough-in, air handler installed | 4.0 total leakage | ANSI/RESNET/ICC 380 or ASTM E1554 |
| Rough-in, air handler not installed | 3.0 total leakage | Air handler added later |
| Post-construction | 4.0 total leakage | Final test with the system complete |
| Ducts and air handler entirely inside the thermal envelope | 8.0 total leakage | Test is still required |
| Ventilation-only ducts | Exempt | Only if not tied into heating or cooling ducts |
Massachusetts measures total duct leakage; "leakage to outside" is not a code option. Under the Massachusetts amendment to R403.3.5, the test must be done by a HERS Rater, HERS Rating Field Inspector or BPI Certified Professional, with a signed report to the Attleboro building department. Mechanical ventilation airflow must also be tested and verified by a HERS Rater under R403.6.3.
Sources: 225 CMR 22.00 (2025 edition) and the 2021 IECC sections listed. Attleboro is in Bristol County, served from our Framingham (68 South St) office.
Duct Leakage Questions from Attleboro Builders
What is the duct leakage limit for a new home in Attleboro?
4.0 CFM25 of total leakage per 100 square feet of conditioned floor area, at rough-in or after construction. If the air handler is not installed at rough-in the limit is 3.0, and if every duct and the air handler are inside the thermal envelope the limit is 8.0.
Can leakage to outside be used instead of total leakage?
No. The Massachusetts code (225 CMR 22.00 R403.3.5) measures total duct leakage. Leakage-to-outside tests are used by some programs, but not for code compliance here.
Who can perform the duct test in Massachusetts?
A HERS Rater, a HERS Rating Field Inspector or a BPI Certified Professional, under the Massachusetts amendment to R403.3.5. The tester signs a written report for the code official.
Is a duct test required if all ducts are inside conditioned space?
Yes. Massachusetts follows the 2021 IECC, which still requires the test but allows up to 8.0 CFM25 per 100 square feet when the ducts and air handler are entirely inside the thermal envelope.
Rough-in or final: which test is better?
A rough-in test catches leaks while every joint is still reachable, so fixes are cheap. A post-construction test confirms the finished system. Many builders do both to avoid surprises at final.
How much does duct leakage testing cost in Attleboro?
Our duct testing is $350 for the first ducted system and $250 for each additional system at the same address. It can be done in the same visit as the blower door test and HERS inspection.
Related: Blower door testing in Attleboro · HERS rating in Attleboro · Stretch Code help in Attleboro
Get Started With Duct Leakage Testing Attleboro MA
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HERS Ratings Across Attleboro and Nearby Communities
Home Energy Efficiency Consultants rates new homes, additions, and major renovations throughout Attleboro — including South Attleboro, Downtown Attleboro, Hebronville, and Dodgeville. Every Attleboro project is filed with the City of Attleboro 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 Attleboro, including North Attleborough, Norton, Rehoboth, Seekonk, and Mansfield. 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 Attleboro rating on the schedule.
