Building permits, zoning and septic rules in the Town of Thompson, New York

At a glance

Building permit

Required for work that must conform to the Uniform Code; issued by the town's code enforcement officer²

Zoning

Yes, the town has its own zoning chapter with districts¹

Certificate of occupancy

Required for work under a building permit and for changes of use⁵

Septic

Health-department approval; office inside Thompson not confirmed³

Floodplain

Separate permit for development in mapped flood hazard areas⁶

Tiny homes

Allowed under the state code if built to Appendix BB, subject to local permits and zoning⁷

Who to call

Contact details are copied from each office’s official page and were checked against it on October 14, 2026.

Does the Town of Thompson have zoning, and what does it mean for your land?

Yes. The Town of Thompson divides the town into zoning districts under its own zoning chapter, and each district has its own schedule of regulations¹. Sullivan County does not zone land; New York gives zoning power to cities, towns and villages, not counties⁴.

That means lot size, setbacks, building height and allowed uses in Thompson depend on which district your parcel is in. We could not confirm those dimensions for each district, so get the district and its schedule from the⁸ before you make an offer.

For manufactured homes, the town's rules we confirmed cover mobile home parks, including access and planning board approval standards⁹. Rules for a single manufactured home on its own lot were not confirmed; ask the town.

Do you need a building permit in the Town of Thompson, and who issues it?

Yes. The Town of Thompson requires a building permit for any work that must conform to the state Uniform Code or the energy code². The town code lists limited exemptions, such as certain one-story detached structures associated with one- or two-family homes, so check before skipping a permit on a shed or outbuilding².

The permit comes from the town's code enforcement officer, and no one may start permitted work before getting it¹⁰. The Building, Planning & Zoning Department also issues certificates of occupancy and plan reviews⁸. A certificate of occupancy is required for any work covered by a building permit and for a change of use⁵.

The town's building-code administration applies to land in Thompson outside the Village of Monticello¹¹. Fees are set by town board resolution; we could not confirm current amounts, so ask the department¹².

How do septic permits work inside the Town of Thompson?

Septic approval in Thompson does not come from the building department. New York routes onsite wastewater approval to the health department having jurisdiction: a state Department of Health district office, a county health department, or in some cases a city health department¹³. For Sullivan County, official state guidance says to contact the local health department or the state Department of Health³.

We could not confirm which office issues septic permits for a parcel inside Thompson. Start with the¹⁴ front desk, which connects callers to the right program.

A parcel inside the New York City watershed portion of Sullivan County also needs NYC DEP review and approval for covered activities¹⁵. Ask which rules apply to your parcel before you close.

Can you live in an RV or tiny home in the Town of Thompson?

We could not confirm whether the Town of Thompson allows living in an RV or travel trailer on private land, or how long a stay is allowed. Ask the⁸ in writing before you buy.

Tiny homes are handled through the state code. A tiny house built to Appendix BB of the New York Residential Code is exempt from the Property Maintenance Code's occupancy limits, but that does not remove building permits, local zoning, or septic requirements⁷. In Thompson, that means a permit from the town and a district that allows a dwelling on your lot²¹.

Building a home in the Town of Thompson: the steps, in order

1. Confirm the zoning district and its dimensional rules with the Building, Planning & Zoning Department¹⁸.
2. Check whether the parcel touches a mapped flood hazard area, which needs a separate floodplain development permit⁶.
3. Get septic approval from the health department having jurisdiction, starting with Sullivan County Public Health¹³¹⁴.
4. If the driveway meets a state highway, get a NYSDOT permit¹⁶.
5. Apply for the building permit from the code enforcement officer before any work starts¹⁰.
6. Keep work exposed for inspection; the state requires inspections of specified construction elements¹⁷.
7. Get the certificate of occupancy before anyone moves in⁵.

What stays with Sullivan County, and what should you check before you buy?

Sullivan County does not issue building permits or set zoning inside Thompson; its planning division offers technical assistance to towns and referral review¹⁸. The county's own answers apply to land outside Thompson; see the Sullivan County page for those.

The county health department is the likely first stop for septic and wells, and the county public works division handles road access on county roads only¹⁴¹⁹. State highways need NYSDOT driveway permits¹⁶.

For context, county figures: the effective property tax rate in Sullivan County is about 2.2%²⁰, and USDA rates only about 0.6% of soils as not limited for a conventional septic drain field, so expect a site evaluation or an engineered system²¹. About 89% of the county is wooded²².

Watch-outs

• Septic approval is separate from the building permit, and we could not confirm which health office issues it inside Thompson, so call Sullivan County Public Health first³¹⁴.
• Rules inside the Village of Monticello come from the village, not the town's building-code administration, which excludes the village¹¹.
• Do not start work without a permit: the town code bars starting permitted work before the code enforcement officer issues it¹⁰.
• Land in a mapped flood hazard area needs a floodplain development permit in addition to the building permit⁶.

Sources

1. Article III: Zoning Districts and Map - Town of Thompson, NY (eCode360) (Town of Thompson), quoted and re-checked
2. Building Code Administration and Enforcement - Town of Thompson, NY (eCode360) (Town of Thompson), quoted and re-checked
3. Septic System Operation and Maintenance, quoted and re-checked
4. documents.dps.ny.gov (New York statewide rule), quoted and re-checked
5. Building Code Administration and Enforcement - Town of Thompson, NY (eCode360) (Town of Thompson), quoted and re-checked
6. Chapter 138: Flood Damage Prevention - Town of Thompson, NY (Town of Thompson), quoted and re-checked
7. 2025 Property Maintenance Code of New York State, quoted and re-checked
8. Town of Thompson Building, Planning & Zoning Department (thompsonny.gov)
9. Article VI: Supplementary Regulations Applicable to Certain Uses - Town of Thompson, NY (Town of Thompson), quoted and re-checked
10. Building Code Administration and Enforcement - Town of Thompson, NY (eCode360) (Town of Thompson), quoted and re-checked
11. Building Code Administration and Enforcement - Town of Thompson, NY (eCode360) (Town of Thompson), quoted and re-checked
12. Building Code Administration and Enforcement - Town of Thompson, NY (eCode360) (Town of Thompson), quoted and re-checked
13. dec.ny.gov, quoted and re-checked
14. Sullivan County Public Health Department (sullivanny.gov)
15. Regulations - DEP, quoted and re-checked
16. Residential Driveway Permits (New York statewide rule), quoted and re-checked
17. Part 1203 Uniform Code and the Energy Code: Minimum Standards for Administration and Enforcement (New York statewide rule), quoted and re-checked
18. Land Use and Zoning, quoted and re-checked
19. dec.ny.gov, quoted and re-checked
20. Effective property tax rate: Bolthole Index county data
21. Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
22. Wooded share of land: Bolthole Index county data

Written October 14, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.