The breakdown
No assessment needed — attic & cathedral ceiling
Attic, from ≤R-12
up to $1,250
Attic, from R-12–25
up to $1,000
Attic, from R-25–35
up to $800
Cathedral ceiling / flat roof
up to $750
Assessment required — walls, foundation, crawlspace
Exterior wall
up to $3,600
Foundation / basement wall
up to $1,500
Basement slab
up to $500
Foundation header
up to $300
Crawlspace wall
up to $1,200
Crawlspace ceiling
up to $1,200
Exposed floor
$300
The attic pays more here than on the no-assessment path
If you're already booking an assessment for other upgrades, do attic insulation through this tier instead — up to $1,500 (vs. $1,250) and $780 for cathedral ceiling (vs. $750).
How to claim it
- For attic: confirm eligibility, pick a participating contractor, get it installed, contractor submits the application
- For walls/foundation: book an energy assessment first, then follow the assessment-path steps
Get an exact number: Fill out our free assessment tool to see your Cambridge-specific rebate amount.
Run your free assessment →
Next steps
View all Cambridge rebate programs → or check the official Home Renovation Savings Program site → for the current source of truth.