Massachusetts now allows ADUs by-right statewide — but you still need code-compliant, PE-stamped engineering to get a building permit. Lebra Engineering & Design handles zoning review, structural design, and permit-ready drawings for attached, detached, garage, and basement ADUs across Marlborough, Acton, Sudbury, Littleton, Quincy, Methuen & Greater Boston.
Find out what's possible on your lot — zoning, structural feasibility, and next steps.
Since February 2025, Massachusetts law requires cities and towns to allow one accessory dwelling unit up to 900 square feet, by-right, on any lot zoned for single-family housing — without a special permit, variance, or public hearing in most cases. That's a major shift, but "by-right" does not mean "engineering-free."
You still need to satisfy dimensional requirements (setbacks, height, lot coverage), owner-occupancy or parking rules some towns retain, and — critically — a full building permit application with structural calculations, foundation design, and often civil/site plans stamped by a licensed engineer.
Lebra Engineering & Design tracks these regulations town-by-town across our Massachusetts service area, so your ADU project moves through zoning and permitting with as few surprises as possible.
Example site concept — front, side, and rear setbacks shown are illustrative; actual dimensional requirements are set by each town's zoning bylaw.
From feasibility to permit-ready plans, we handle the technical work so your ADU gets approved the first time.
We review your lot, goals, and budget for ADU feasibility.
We confirm dimensional compliance under the by-right ADU law.
For conversions, we laser-scan existing conditions for accuracy.
PE-stamped drawings covering structure, egress, and systems.
We package and support your submittal to the local building department.
Town-by-town zoning knowledge reduces plan review delays.
3D scanning and thorough feasibility review reduce costly surprises.
Designs built to maximize livable space within by-right limits.
Structural, civil, and MEP coordination handled under one roof.
Full structural design and by-right zoning compliance review for a new detached ADU, permitted without a variance.
3D-scan-based structural evaluation and design to convert an attached two-car garage into a code-compliant ADU.
Egress, ceiling height, and fire-separation design enabling a compliant basement accessory unit.
Find out what's possible on your lot under the new by-right ADU law — and get a clear path to permit-ready plans.