Home additions in Belmont, MA

Belmont rules that apply

What Belmont requires for home additions.

1. 1

   Demolition delay for listed buildings

   For buildings on Belmont's List of Historically Significant Buildings, a demolition or partial demolition permit is paused until the Historic District Commission holds a hearing. If the building is found preferably preserved, a 12-month stay follows while alternatives are explored.

   Source: Belmont Historic District Commission: Demolition Delay Process flowchart, 2026 (PDF)

2. 2

   Stormwater and erosion control permit

   A permit from the Office of Community Development is required to disturb 2,500 square feet or more, raise a lot's impervious area above 25% of the lot, or place more than 100 cubic yards of fill. The permit packet applies the bylaw to new houses and substantial renovations of one- to three-family homes.

   Source: Belmont: Stormwater Management and Erosion Control Rules and Regulations, amended 2023 (PDF)

3. 3

   Surveyor plot plan with lot coverage

   Every permit for a new building, accessory building or addition needs a plot plan stamped by a Massachusetts registered land surveyor. It must follow the town's plot plan regulations and show existing and proposed open space and lot coverage percentages.

   Source: Belmont Office of Planning & Building: Building Permit Application Packet, One and Two Family (PDF)

4. 4

   ADUs under Section 6.14

   Belmont's ADU bylaw, Section 6.14, was approved at the March 2025 Town Meeting to meet the state's 2024 housing law. The town's info session notes that a new detached ADU follows the Specialized ('net zero') energy code, while an attached ADU added to a two-family is treated as a three-family under the building code.

   Source: Belmont ADU Information Event: Belmont ADU Bylaw Simplified (PDF)