Permits for below-grade work in Boston

Small Project Review generally applies to projects that add 20,000 square feet or more of gross floor area, or 15 or more dwelling units. Large Project Review applies from 50,000 square feet in most of the city and from 10,000 square feet in the Harborpark districts. (Source: Zoning Code §§80B-2, 80E-2) (Source: Small Project Review) (Source: Large Project Review)

ISD won’t issue a building permit for a project in either review until the Planning Department certifies it: a Certification of Compliance after Large Project Review, or a Certification of Approval after Small Project Review, unless that review is waived or the Department misses its review deadline. (Source: Zoning Code §§80B-6, 80E-6)

Does a basement count toward the thresholds?

Not always. Boston’s zoning definition of gross floor area leaves out garage space in a basement, and basement or cellar areas used only for purposes accessory to running the building. Below-grade floor area used for anything else, such as living space or a shop, counts. (Source: Zoning Code Art. 2, Floor Area, Gross)

In Large Project Review the Planning Department can require a groundwater study of “the impact of construction on groundwater levels and resulting effects on surrounding structures, wooden piles, and foundations,” and a geotechnical impact study covering ground movement during construction, the effect on adjacent buildings and utility lines, and the foundation construction method. (Source: Zoning Code §80B-3.2) On a large project, expect questions about the dig before the building permit is filed.

Article 32 applies when a project in the district builds or extends space for occupancy, mechanical equipment, laundry or storage, garage space included, and the excavation reaches elevation 8 feet Boston City Base or lower. Adding more than 50 square feet of ground-floor coverage, or new or replacement paving, triggers it too. (Source: Zoning Code §32-3)

The permit depends on a GCOD certification from a Massachusetts registered engineer: the project has to capture and infiltrate at least 1 inch of rain over its roofs and other impervious surfaces, and cause no negative impact on groundwater levels on the lot or the lots next to it. Staff from ISD, the Boston Water and Sewer Commission (BWSC) and the Boston Groundwater Trust review the certification before the permit issues. The article was last amended on October 28, 2025. (Source: Zoning Code §32-3)

Our guide to building below grade in the GCOD covers the map, the certification and what it means for a basement lowering.

Getting to a foundation permit

ISD takes a foundation permit only after a long-form building permit application is on file. At the counter you’ll need plans stamped by ISD’s Plans and Zoning division, a description of the foundation, a signed agreement to follow the code and the permit, proof you’re working with a licensed rodent-control company, approval from BWSC, and the fee. (Source: ISD foundation permit)

ISD’s own guide says a long-form review takes four to five weeks, depending on the project’s size, when the application is complete and needs no zoning or building relief. (Source: ISD permit guide) ISD construction and demolition permits also need a Site Safety Plan Affidavit, and a site larger than 50,000 square feet needs a Site Safety Coordinator present from excavation until the building is enclosed. (Source: Safe Construction Ordinance)

What the design package has to cover

• A geotechnical report. 780 CMR lists it with the construction documents submitted with a permit application, and ISD’s checklist for new buildings over 35,000 cubic feet calls for one with foundation recommendations by a Massachusetts registered professional engineer. (Source: 780 CMR 107.1) (Source: ISD permit checklist)
• An assessment of any foundation the dig will undermine. Where excavation will reduce support from any foundation, a registered design professional has to assess the structure and prepare site-specific plans, details and a sequence of work for submission. (Source: IBC 2021 §1803.5.7)
• A support-of-excavation design. Where the support protects adjacent structures, a registered design professional has to design it, including requirements for monitoring the system and those structures for horizontal and vertical movement. (Source: IBC 2021 §3307.2) Massachusetts adds that any retaining system that could affect public safety or the stability of an adjacent structure must be designed by a registered design professional. (Source: 780 CMR 1807.2.1)
• The underpinning sequence, if the job has underpinning. The code wants it in the approved construction documents. (Source: IBC 2021 §1804.2.1)

Is shoring a separate permit?

ISD doesn’t publish a separate shoring application. (Source: ISD forms) Its permit records show support of excavation permitted three ways: inside a foundation permit, as an amendment to a long-form permit, and as an early short-form permit under the work type “Excavation, Borings, Test Pits.” (Source: ISD permit records)

The state code gives the building official the tools for this. A phased approval lets foundation work proceed before the whole building is permitted, at the permit holder’s own risk, and deferred submittals can’t be installed until they’re approved. (Source: 780 CMR 107.3.4–107.3.5) Ask your plan reviewer early which route fits the job.

Construction control

Construction control under 780 CMR 107.6 applies to buildings that need a registered design professional, except those under 35,000 cubic feet of enclosed space (basement levels count toward the volume), one- and two-family homes, retaining walls under 10 feet high, and a few others. The design professionals review shop drawings and submittals, carry out their special-inspection duties, visit at intervals and file a final report with the building official. The general contractor named on the permit is responsible for the construction and certifies it at completion. (Source: 780 CMR 107.6) ISD’s checklist asks for a Construction Control Documents Affidavit from the design professionals. (Source: ISD permit checklist)

The Public Improvement Commission (PIC) approves the use of a public way for earth retention systems. (Source: PIC) Its procedure covers any earth retention system installed within the public right-of-way, and permits for the work follow its approval. (Source: PIC earth retention procedure) The Commission is managed by Public Works and chaired by the Public Works Commissioner; its members include the Commissioners of Property Management, Inspectional Services and Transportation, the Disabilities Commission and the Executive Director of BWSC. (Source: PIC)

The PIC’s earth retention procedure

1. 1
   Plans on 24-by-36-inch sheets with the PIC title block, stamped and signed by a Massachusetts-registered civil or structural engineer.
2. 2
   Written approval from the Boston Transportation Department (BTD), ISD and BWSC.
3. 3
   Plans sent by certified mail to the private utility companies. They don’t have to answer, but their comments have to be addressed.
4. 4
   A License, Maintenance and Indemnification (LMI) agreement, drafted with the PIC’s legal counsel.
5. 5
   A full submission: three sets of plans and an engineering report with the signed petition, the agency letters, the utilities’ delivery receipts, a manager’s certificate or certificate of authority, and a certificate of insurance at the limits the PIC specifies.
6. 6
   A “New Business” hearing, revisions if the Commission asks for them, then a vote at a Public Hearing.
7. 7
   A Mylar of the approved plans. Then permits can issue and construction can start.

Steps from the PIC’s Earth Retention System procedure, linked from its page. (Source: PIC earth retention procedure)

The Commission meets every two weeks, on Thursdays at 10 a.m. in City Hall. To get on a New Business agenda, file by the Thursday before the hearing you want. Monitoring wells in the public way need PIC approval too, and repairing or filling an areaway under the sidewalk means consulting the PIC and other City departments. (Source: PIC)

Do the tendons have to be de-tensioned or pulled?

The building code rule is about when, not how. Elements of a retention system may only be removed or decommissioned where backfill or the new structure provides adequate replacement support, and the work has to protect the adjacent property. (Source: IBC 2021 §3307.2.3)

The PIC’s published checklist doesn’t set a general rule for tendons left under a street, and we didn’t find one in the hearing minutes it has posted for January 2024 through October 2025. (Source: PIC earth retention procedure) (Source: PIC minutes) What those minutes do record is how deep the piles and sheeting left in the street get cut off: at least 6 feet below finished grade on one petition, and 6 feet below sidewalks and 10 feet below roadways on another. (Source: PIC minutes)

The PIC license covers the public way. Anchors that would run under a neighboring private lot need that owner’s agreement, which is a private negotiation, not a City permit.

Public Works issues street occupancy and excavation permits through its online portal. You’ll need your traffic plan and your plan for a Boston police detail, proof that your company is bonded with the City (the bond amounts are on the Public Works page), and a clear scope: how much of the street you’ll use, dumpsters, fencing, trucks. If the job needs a Construction Management Plan, that’s reviewed and negotiated with BTD. (Source: Public Works permits)

Every Public Works permit runs through COBUCS, the City’s utility-coordination system. A street rebuilt in the last five years is a “Guaranteed Street,” with its own approval form and tighter restoration rules. (Source: Public Works rules) (Source: Public Works permits)

Warn the neighbors before you take the space. In residential areas, post signs at least three days ahead and hand out the Public Works flier within half a block, every day for at least two days before the work; for metered spaces, signs go up two days ahead and fliers one day ahead. (Source: Public Works permits)

Massachusetts law defines a trench as “an excavation which is narrow in relation to its length, made below the surface ground in excess of 3 feet below grade and the depth of which is, in general, greater than the width, but the width of the trench, as measured at the bottom, is no greater than 15 feet.” (Source: M.G.L. c. 82A §4) No one may make a trench, or contract for one, in a public way, on public property or on private land without a permit, except in an emergency. (Source: M.G.L. c. 82A §2) (Source: 520 CMR 14.03)

In Boston, ISD issues trench permits on private property. In the public way, Public Works’ permit branch issues its own, on top of the street opening permit. (Source: ISD trench permit form) (Source: Public Works rules §3.09) On land owned or controlled by a state agency, such as MassDOT, the permit comes from that agency. (Source: 520 CMR 14.03(2))

A basement dig wider than 15 feet at the bottom isn’t a trench by that definition. The footing, grade-beam and utility trenches around it often are.

What you file

A completed application, a certificate of insurance and any fee. The application carries your Dig Safe number, the excavator’s details, an after-hours emergency contact, the trench location and the insurer’s name and contact. (Source: 520 CMR 14.03(3)–(4)) Boston’s ISD form also asks for the competent person and the operator’s hoisting-license number and grade, and the owner, applicant and excavator all sign it. (Source: ISD trench permit form)

Insurance and bonds

State law requires the applicant to produce a certificate of general liability insurance at minimum limits written into the statute, or evidence of self-insurance in the same amounts. (Source: M.G.L. c. 82A §2) For trenches in the street, Public Works’ rules set their own, higher liability limits, and an excavation permit there also needs a surety bond. (Source: Public Works rules §3.02) (Source: Public Works permits)

On site

Post the permit in plain view at the trench. (Source: 520 CMR 14.03(5)) When no one is at an open trench, cover it with steel plates at least 3/4 inch thick, surround it with barriers at least 6 feet high, keep someone watching it, or backfill it. (Source: 520 CMR 14.04) Anyone running hoisting equipment on the dig needs a state hoisting license and has to be shown the permit before digging starts. (Source: 520 CMR 14.03(7))

BWSC lists dewatering drainage and water from the excavation of a foundation or trench among the discharges that need its permit. (Source: BWSC dewatering permit) Into a separate storm drain you also need EPA coverage under an NPDES general permit, or an NPDES exclusion. Into a sanitary or combined sewer, or a storm drain that feeds the combined system, you need an MWRA Sewer Use Discharge Permit. BWSC will deny or revoke its permit if those aren’t in place. (Source: BWSC dewatering permit) (Source: BWSC application)

The application is signed by the property owner’s authorized representative and comes with a site plan showing where the water comes from and where it goes in. (Source: BWSC application)

Which EPA permit

EPA Region 1’s Dewatering and Remediation General Permit (DRGP) replaced the separate dewatering and remediation general permits in 2022. It covers site dewatering at construction sites under 1 acre, whatever is in the water, and at sites of any size where the water carries pollutants. (Source: EPA DRGP) (Source: DRGP permit text) Sites of an acre or more need EPA’s Construction General Permit for their stormwater, and its rules control dewatering too; if their pumped groundwater carries pollutants above a water-quality standard, that discharge goes under the DRGP. (Source: EPA CGP) (Source: DRGP permit text)

EPA takes the DRGP Notice of Intent electronically and suggests filing 30 days before discharge begins. (Source: EPA DRGP) The 2022 DRGP runs five years from its effective date; the 2022 Construction General Permit expires February 16, 2027, and EPA has proposed its replacement. (Source: DRGP permit text) (Source: EPA CGP)

The drawdown itself

Massachusetts adds a rule the IBC doesn’t have: below-grade structures, their appurtenances and foundation drains must be designed and built so they don’t change temporary or permanent groundwater levels where that could harm nearby structures or facilities, through deterioration of timber piles, settlement, flooding or other impacts. (Source: 780 CMR 1805.5) In the GCOD, the engineer’s certification has to show no negative impact on groundwater levels on the lot or next door. (Source: Zoning Code Art. 32)

Massachusetts’ tenth edition of 780 CMR is built on the 2021 IBC. Its Chapter 33 amendments deal with fire safety, construction documents and demolition, and leave Section 3307 as the IBC prints it. (Source: 780 CMR ch. 33) The tenth edition has been the only building code in effect since June 30, 2025. (Source: 780 CMR, 10th ed.)

Two more sections of the same code bear on the building next door. Existing footings or foundations that can be affected by any excavation must be underpinned adequately or otherwise protected against settlement and lateral movement, (Source: IBC 2021 §3304.1.2) and excavation for any purpose can’t reduce vertical or lateral support for any foundation or adjacent foundation without first underpinning or protecting it. (Source: IBC 2021 §1804)

Sending the notice

The code sets the content: that the excavation is going to be made, and that the adjoining buildings should be protected. It has to be in writing and delivered to the owners at least 10 days before the scheduled start. Date it, deliver it in a way you can prove, and keep a copy with the permit file.

If you’re on the other side of the fence, read what to ask for when your neighbor is excavating.

That comes from the Dig Safe law, and the Department of Public Utilities’ regulations spell it out for any excavation. (Source: M.G.L. c. 82 §40A) (Source: 220 CMR 99.03–99.04)

The duty sits with the excavator, the one doing the work, and “excavation” in the law includes drilling, augering, test boring and pile driving. The crew drilling soldier piles or tiebacks is an excavator too. (Source: M.G.L. c. 82 §40) (Source: 220 CMR 99.02, 99.04) Dig Safe recommends that the contractor, not the owner, make the call. (Source: Dig Safe FAQ)

Premark first: white paint on pavement, or white flags or stakes elsewhere. Pink is allowed where white could interfere with traffic or be hard to see, as long as you tell Dig Safe. (Source: 220 CMR 99.03) Member utilities then mark their lines within 72 hours, again not counting weekends and holidays, and at least 15 feet beyond your premark. (Source: M.G.L. c. 82 §40B) (Source: 220 CMR 99.06)

A Massachusetts ticket is valid for 30 calendar days while the marks stay clear and discernible. Keeping the marks up is your job; if you ask for a remark, the utility has 24 hours (not counting weekends and holidays) and you stop digging in that area for 24 hours. (Source: M.G.L. c. 82 §40C) (Source: 220 CMR 99.06–99.07) Within 18 inches of a marked line, expose it by hand or with vacuum excavation. (Source: Dig Safe: how it works)

Dig Safe notifies only its member utilities. Non-member owners, such as municipalities, are yours to contact directly, and private lines on the site are yours to locate. (Source: Dig Safe: how it works) Your trench permit application has to carry the Dig Safe number. (Source: 520 CMR 14.03(4))

The application is due by noon on the Thursday before the proposed date, with an on-site contact, the days and hours, a description of the work, a justification and a plan to limit noise, light and other disruption. ISD’s form lists the justifications it accepts (emergency repairs, essential utility work, support for critical public services, low-impact interior work, and a narrow commissioner’s discretion category) and says project delays or contractor availability are not valid reasons. (Source: ISD Off Hours Permit)

In the street, night and weekend work also needs approval from the Public Works Construction Management Division and BTD before you apply for the permit. (Source: Public Works rules §3.11) Changes to a street permit’s dates or times go through BTD’s permit branch. (Source: Public Works permits)

Need an ISD inspection outside business hours? That’s a separate request, paid in advance; for a same-day inspection, file and pay by noon on the business day before. (Source: ISD bulletin CB2026-02)

• Owner or developer

  Holds the zoning approvals and the right to use the street

  • Article 80 filings with the Planning Department
  • The GCOD appeal to the Zoning Board of Appeal
  • The PIC petition and the License, Maintenance and Indemnification agreement
  • The BWSC dewatering application, signed by the owner's authorized representative
  • Signs Boston's trench permit form as owner

• General contractor

  Named on the building permit and responsible for the work

  • The long-form building permit and the foundation permit
  • Street occupancy permits for staging and deliveries
  • Off Hours Permits
  • The 10-day notice to adjoining owners, usually with the owner
  • Dig Safe tickets and trench permits for its own digging

• Shoring and underpinning subcontractor

  That's us: we install to the approved design

  • Dig Safe tickets for our own drilling
  • Trench permits for any trench our crew opens
  • Installer submittals for the engineer and ISD: equipment, sequence, anchor test records
  • Answers at PIC and ISD reviews when the team wants the installer in the room

• Engineer of record and geotechnical engineer

  Designs, stamps and certifies

  • The geotechnical report
  • The assessment of any adjacent foundation the dig undermines
  • The support-of-excavation and underpinning design, with its monitoring requirements
  • Stamped earth retention plans for the PIC and the GCOD certification
  • Construction-control affidavits and the final report to ISD

Where the split comes from: the general contractor named on the permit is responsible for the construction. (Source: 780 CMR 107.6.3) The interested party signs the PIC petition. (Source: PIC earth retention procedure) The owner’s representative signs the BWSC application. (Source: BWSC application) Owner, applicant and excavator all sign Boston’s trench form. (Source: ISD trench permit form) The excavator gives Dig Safe notice. (Source: 220 CMR 99.00) The rest is common practice, not law.

Where we fit

Earth Support Corp. is a specialty subcontractor. We install shoring and support of excavation, tiebacks and anchors and underpinningto the engineer of record’s design, for builders, GCs, developers and engineers. We don’t hold the building permit and we don’t design the system. If a cut or a neighbor’s wall is already moving, see emergency shoring. Back to the permit table.