Montgomery County, MD zoning map, flood zone and property lines by address
Free, no account. Or open the Maryland map and tap a lot.
Towns in Montgomery County: Germantown, Silver Spring, Gaithersburg.
Flood zone by address
ParcelSheet reads FEMA's National Flood Hazard Layer at the lot: the zone, whether it is a high risk area where lenders ask for flood insurance, and the base flood elevation where FEMA lists one. FEMA's countywide study for Montgomery County has 84 FIRM panels, the newest effective September 2006; no coastal V zones are mapped in it.
The official panel and any Letter of Map Amendment are at FEMA's Map Service Center. An elevation certificate for a Montgomery house comes from a licensed surveyor and is often on file with the county or city building office.
Property lines
The parcel outline, parcel number and mapped size come from the Maryland Department of Planning, statewide parcel boundaries (MD iMAP), so a Montgomery lot shows the same lines the state Department of Assessments and Taxation draws. Montgomery County covers about 315,604 acres of land and 8,805 acres of water.
Mapped lines are approximate. The Maryland Department of Assessments and Taxation keeps the parcel record (Montgomery County website); a licensed surveyor sets the true corners.
Zoning
Montgomery County zones its unincorporated land, and Gaithersburg zones the land inside its limits. ParcelSheet shows the use the state Department of Assessments and Taxation lists for the lot and links the county planning and zoning office for the district, the uses it allows and the lot size it needs.
ADU and guest houses
Under Maryland's Land Use Article (Annotated Code of Maryland, Land Use Title 4, Zoning), local governments can allow an accessory dwelling unit on a lot with a house. Whether a Montgomery lot can add one depends on its district; the county planning and zoning office has the rule. ParcelSheet shows the mapped lot size and the ground's slope, the first two things the question turns on.
Septic and soil
ParcelSheet reads the USDA soil survey at the lot: the soil's name, its septic absorption rating and whether it is prime farmland. Montgomery County is soil survey area MD031, Montgomery County, Maryland, last updated September 2026, on Web Soil Survey.
A new or changed septic system in Montgomery County needs a permit from the Montgomery County health department (under Maryland Department of the Environment onsite systems rules).
Setbacks
Setbacks in Montgomery County come from the zoning district: the front, side and rear distances a house must keep. ParcelSheet does not draw setback lines; the county zoning office gives them for the lot's district, and Gaithersburg for land inside its limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Montgomery lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Montgomery County?
Type the address in the box above and ParcelSheet reads FEMA's flood zone at the lot's center. FEMA's countywide flood map for Montgomery County has 84 panels, the newest effective September 2006. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Montgomery County?
Open the Maryland map, type the address, and the parcel outline from the Maryland Department of Assessments and Taxation shows on the map with its parcel number and mapped size. Mapped lines are approximate; only a licensed surveyor sets the true corners.
What is my property zoned in Montgomery County?
Zoning in Montgomery County is set by the county for unincorporated land and by each city (such as Gaithersburg) inside its own limits. ParcelSheet shows the use code the state Department of Assessments and Taxation lists and links the office that sets the zoning; the planning office has the final word.
Can I build an ADU in Montgomery County?
Under Maryland's Land Use Article (Annotated Code of Maryland, Land Use Title 4, Zoning), counties and cities can allow an accessory dwelling unit, and each sets its own rules. In Montgomery County ask the zoning office for the lot's district first; ParcelSheet shows the lot size as mapped so you can see the room you have.
Do I need a septic permit in Montgomery County?
Yes. A new or changed septic system in Montgomery County needs a permit from the Montgomery County health department (under Maryland Department of the Environment onsite systems rules). ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area MD031 (Montgomery County, Maryland).
What can I build on 5 acres in Montgomery County?
Zoning in Montgomery County is set by the county for unincorporated land and each city inside its own limits (such as Gaithersburg). The zoning district decides the uses, how many homes and the smallest lot it allows on 5 acres. ParcelSheet shows the lot size as mapped and the use code on the parcel record; the planning office has the district and its rules. See the Montgomery County website.
What are the residential setbacks in Montgomery County (2026)?
Setbacks in Montgomery County come from the zoning code of the county, or of the city when the lot is inside city limits: the front, side and rear distances depend on the lot's district. ParcelSheet does not draw setback lines or give a number it did not read; the zoning office gives them for the district. See the Montgomery County website.
Next to Montgomery County: Frederick County, Howard County, Prince George's County.
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