The Complete Massachusetts Weatherization Guide (2026 Pillar Reference).

Mass Save Weatherization Program Overview

Mass Save weatherization rebates fund: air sealing (typically 100% covered), insulation (1,000-$4,000 typical rebate), ENERGY STAR windows ($600/window cap), and ENERGY STAR doors. Eligibility requires Mass Save Home Energy Assessment within prior 6 months.

Tier-based subsidy:

Standard Tier (above 80% AMI)

~75% subsidy on insulation, 100% on air sealing, partial on windows. Typical out-of-pocket: $1,000-$3,000 on $4K-$8K project.

Moderate Income (60-80% AMI)

~90% subsidy on insulation, 100% on air sealing. Typical out-of-pocket: $300-$800.

Income Eligible Enhanced (under 60% AMI)

100% on insulation + air sealing. Out-of-pocket: $0 on most projects.

Greater Boston metro 60% AMI for family of 4 was ~$80,800 in 2025 — IE Enhanced tier covers much broader population than name suggests. Verify tier at masssave.com via 2 pay stubs or prior tax return.

The Mandatory Sequence

Mass Save mandates specific weatherization sequence. Skipping or reordering disqualifies rebate filing:

1. Home Energy Assessment (HEA) — Free 90-min on-site visit. Required within 6 months before work begins. Schedule 3-6 weeks out.
2. Income tier verification — If suspect Moderate Income or IE Enhanced eligibility. 5-10 business days.
3. Authorized contractor selection — Verify at masssave.com/find-a-contractor.
4. Knob-and-tube wiring assessment — Required removal before insulating affected cavities. Common in pre-1950 MA homes.
5. Blower door test (baseline) — Measures air infiltration before work.
6. Air sealing — Attic penetrations, basement rim joists, can lights, ducts. 100% Mass Save subsidy typical.
7. Blower door test (post-sealing) — Required to qualify insulation rebate.
8. Insulation install — Attic, walls, basement, rim joists per HEA recommendations.
9. Final inspection + blower door — Mass Save inspector verification.
10. Rebate filing — Contractor files within 30 days. Check 6-8 weeks.

Insulation Type Selection by Application

Different cavities need different insulation. Type selection by application:

Attic (open)

Blown cellulose (R-3.7/inch) is the MA standard. Mass Save target R-49. Cost $1.50/sq ft installed. Or fiberglass batts for accessible flat areas.

Wall cavities (existing)

Dense-pack cellulose (R-3.7/inch in 2x4 cavity = R-13). Blown through interior or exterior drill holes. $1.50/sq ft. See 10 Best Insulation Types MA Old-Home Walls.

Wall cavities (new construction)

Closed-cell spray foam (R-6.5/inch = R-23 in 2x4). Vapor barrier + air seal in one. $4.50/sq ft.

Basement walls

Closed-cell spray foam against foundation OR XPS rigid foam. Both handle moisture.

Rim joists

Closed-cell spray foam (best) or XPS rigid foam with sealing.

Crawl space

Encapsulation (vapor barrier + insulation on walls) preferred over batts on floor.

9 Common Mistakes That Forfeit the Rebate

Mass Save weatherization rebates fail on ~1 in 8 projects. The 9 mistakes:

1. No HEA on file (or expired beyond 6 months)
2. Non-authorized contractor
3. Insulation installed without prior air sealing
4. Insulated cavities contained knob-and-tube wiring
5. Existing insulation not addressed (added on top vs replaced)
6. Wrong income tier on filing
7. Documentation/receipts not retained
8. Filed after program year cutoff
9. Project doesn't meet program minimum scope

Each preventable at the planning stage. Full prevention checklist in 9 Mass Save Mistakes That Forfeit Rebate.

Authorized Contractor Verification

Mass Save has 3 distinct authorization tiers — knowing which a contractor holds determines which rebates can be filed:

General Mass Save Approved

Base level. Files: gas boilers, central AC, water heater, HVAC tune-ups.

Mass Save Heat Pump Coach (HPC)

Required for heat pump rebates ($10K-$16K). Layered on General Approved.

Income Eligible Enhanced Authorized

Required for IE Enhanced tier rebates (up to 100% coverage). Additional documentation discipline.

Verify all three tiers at masssave.com/find-a-contractor. Full guide: What 'Mass Save Approved Contractor' Actually Means.

Next Steps for MA Weatherization Projects

Plan a weatherization project:

1. Schedule Mass Save HEA at masssave.com (free, 3-6 week wait).
2. Verify income tier if suspect Moderate/IE Enhanced eligibility.
3. Identify K&T wiring in pre-1950 homes (remove before insulating).
4. Select authorized contractor (verify tier at masssave.com).
5. Schedule project (air seal → insulate → final inspection → rebate filing).
6. Bundle with siding or roofing if those projects coming up — combined work captures more rebate.