Appendix 120.G "Flood Resistant Construction and Construction in Coastal Dunes" of the state building code defines the regulations that affect new construction and substantial improvements in flood hazard areas. While there are several specific requirements for development in the floodplain which vary by the hazard area and the type of construction taking place, there are two important regulations that are often misunderstood and can affect insurance premiums as well as your community's standing in the NFIP.

Compliant enclosure below BFE in an A zone The Massachusetts State Building Code defines a basement or cellar as "Any area of the building having its floor subgrade (below ground level) on all sides". This section of the code does not differentiate between crawl spaces and basements based on headroom. Appendix 120.G further states "Except as otherwise provided in 120.G.501, all buildings or structures, including new or replacement manufactured homes, erected or substantially improved within a flood-hazard zone shall be elevated so that the lowest floor is located at or above the base flood elevation. All basement/cellar floor surfaces shall be located at or above the base flood elevations." Since the floor of a "basement" (below grade) will not be above the flood elevation (above grade), basement construction is not compliant with Appendix 120.G. Failure to elevate the lowest floor, including basements or cellars, to at or above the base flood elevation (BFE) will result in a building that is not only non compliant with the state building code, but may also have very high flood insurance premiums due to its increased risk and susceptibility to flood damage. Enclosures below the base flood elevation are allowed in A zones, if the floor of the enclosure is above grade on at least one side (not a basement) and it meets the remaining requirements of 120.G501.4. This type of enclosure is not allowed in a V-Zone, as Appendix 120.G601.2 requires that the lowest horizontal structural member be elevated to at least two feet above the BFE on an open foundation (piles of columns as stated in 120.G601.4). Appendix 120.G701 and 120.G801 contain the requirements for design and construction in coastal dunes significant to the interests of flood control and/or storm damage prevention identified in 310 CMR 10.28: Coastal Dunes.

The other very important and often misunderstood section of the State Building Code is the regulation concerning substantial improvements in flood hazard areas. Appendix 120.G of the Massachusetts State Building Code includes the following definition for substantial improvement: " Substantial improvement means any reconstruction, rehabilitation, addition, repair or improvement of a structure, the cost of which equals or exceeds 50% of the market value of the structure before the "start of construction" of the improvement. This term includes structures which have incurred " Substantial damage", regardless of the actual repair work performed." It is also important to note that the substantial damage regulation applies to damage from any source , not just damage from flooding. Additional information can be found in FEMA Publication 213, "Answers to Questions About Substantially Damaged Buildings".

Example of elevated ductwork

Many homeowners are unaware that their policy may provide up to $30,000.00 in additional funds to assist in covering the cost of compliance with local, state and federal requirements. "ICC" or the "Increased Cost of Compliance" is available as a part of most flood insurance policies and can be used for four types of activities including, elevation, relocation, demolition and floodproofing. Additional financial assistance may be available through one of several FEMA mitigation grants. Please visit our Hazard Mitigation page for more information on FEMA mitigation grant programs.

*The information provided on this website is advisory only and does not cover all of the requirements contained in the State Building Code. Please reference the Massachusetts State Building Code for specific building regulations and contact the Board of Building Regulations and Standards for official interpretations.



Elevation Certificate

Massachusetts communities must comply not only with federal regulations, but also with state and local regulations which may be more restrictive. 310 CMR 10.00 of the Wetlands Protection Act regulates development in wetlands areas and includes a requirement for compensatory storage in wetland/floodplain areas. It is important to work closely with the local Conservation Agent regarding all development within wetland/floodplain areas. 310 CMR 15.213 or Title V of the State Sanitary Code regulates the placement of septic systems in floodways and velocity zones. Your local Board of Health official would be the point of contact for any proposals that involve the provisions of Title V.


The Massachusetts Office of Coastal Zone Management has developed a comprehensive guide to environmental permitting in Massachusetts. The guide provides a wealth of information about the various regulations and permits that affect development in Massachusetts.


Communities that participate in the NFIP must adopt and abide by a floodplain district bylaw or ordinance that regulates development within their flood hazard areas as shown on their FEMA Flood Insurance Rate Map. Adoption and enforcement of this bylaw will allow the community to meet the minimum regulatory requirements required for participation in the NFIP. Most of the minimum NFIP standards are included in the State Building Code, Wetlands Act and Title V. The local floodplain bylaw should include the minimum NFIP standards that are not addressed in the above mentioned regulations, as well as any locally adopted more restrictive provisions. The FHMP has created a model bylaw for floodplain districts in an effort to ensure that local bylaws are compliant with NFIP minimum requirements. Please contact the FHMP for a paper or electronic copy. The FHMP offers assistance to communities who wish to adopt a floodplain district bylaw or update an existing bylaw.

Floodproofing Certificate



The Community Rating System or CRS is a point based system that rewards communities through insurance premium discounts for adopting and enforcing floodplain management activities that go above and beyond the NFIP minimum standards. There are currently 13 Massachusetts communities who are participating in the program. Their residents are benefiting not only from discounts on their flood insurance premiums, but also from stronger floodplain management activities that result in reduced losses from flooding. For more information on CRS, please visit the Community Rating System Resource Center, or contact the FHMP.

CZM Comprehensive Coastal Permitting Guide:(

Massachusetts Board of Building Regulations and Standards:

FEMA Floodproofing Certificate (

Managing Floodplain Development in Approximate Zone A Areas (

Coastal Construction Manual (

Homebuilders Guide to Coastal Construction - Technical Fact Sheet Series: (

Protecting Building Utilities From Flood Damage (

Elevated Residential Structures

Floodproofing Non-Residential Structures

FEMA Technical Bulletins

All FEMA Floodplain Management Publications (

Emergency Management Institute 

DCR Office of Dam Safety (

Army Corps of Engineers New England District (



Massachusetts Coastal Zone Management (

Massachusetts Department of Environmental Protection

Association of State Floodplain Managers(