Zoning, building permits and septic rules in the Village of Cary, Illinois

At a glance

Building permit

Required inside Cary village limits for most projects, including accessory structures, fences, driveways and decks²³

Zoning

Cary adopts its own zoning ordinance with districts E1, R1, R2, R2A, R3, B1, B2, B3, B3R, M, A-1 and PO¹⁵

Building code

2021 International Residential Code with local amendments⁶

Driveway permit

Required inside the village; fee of $150 per the village fee schedule⁷

Septic

McHenry County Department of Health permits septic systems in McHenry County; not confirmed for lots inside Cary⁴

RV living

Camping is banned in the village park; rules for RVs on private lots not confirmed⁸

Owner-builder

Illinois exempts owner-occupants from the plumber-license requirement for their own home's plumbing only; no general permit exemption⁹

Who to call

Contact details are copied from each office’s official page and were checked against it on October 17, 2026.

Does Cary, Illinois have zoning, and what does it mean for RVs, tiny homes and lot size?

Yes. The Village of Cary adopts its own Unified Development Ordinance (Title 14), with zoning districts and a Table of Permitted Uses¹. The districts are E1, R1, R2, R2A, R3, B1, B2, B3, B3R, M, A-1 and PO⁵. Inside Cary, a use not marked X or C in the table is not permitted, and the Director of Community Development decides uses the table does not list¹.

The village's A-1 district is its agricultural district, meant for agricultural, forestry, passive recreation, parks, and mining and mineral extraction uses⁵. The Village of Cary Planning & Zoning Division works with the Board of Zoning, Planning and Appeals¹⁰.

We could not confirm Cary's minimum lot sizes, setbacks, height limits, tiny-home rules or accessory dwelling rules by district. Ask the Community Development Department before you buy a lot, and name the district when you ask³.

Do you need a building permit in Cary, Illinois, and who issues it?

Yes. Cary requires building permits for construction inside village limits, including accessory structures, fences, sidewalks, driveways and decks². The village's own permits page says building permits are required for most home improvement and remodeling projects³. Retaining walls taller than 2 feet also need permits².

The Village of Cary Community Development Department issues them³. McHenry County's building permit rules cover unincorporated land only¹¹, so use the McHenry County page only for land outside the village.

Cary enforces the 2021 International Residential Code with local amendments for one- and two-family homes⁶. A driveway needs its own permit inside the village, with a $150 fee⁷. Building permit fees follow the village's fee schedule, and a certificate of occupancy fee is $50¹².

How do septic permits work inside Cary, Illinois?

Septic permits in McHenry County come from the McHenry County Department of Health, Environmental Health Division, which says a permit is required to install, modify, alter, extend, repair, replace or abandon a septic system in McHenry County¹³. The county's septic permit guide says the same for the whole county⁴.

We could not confirm whether a given lot inside Cary is on village sewer or would need a septic system, or how the county health department handles lots inside village limits. Ask the Community Development Department about sewer service for your address, and the McHenry County Department of Health about any septic permit³¹³.

For land with no sewer, a site evaluation determines whether a permit can be issued for a new residence or structure¹³. Soils matter here: only about 2.5% of McHenry County soils are rated not limited for a conventional drain field, so expect a site evaluation and possibly an engineered system¹⁴.

Can you live in an RV or tiny home on your lot in Cary, Illinois?

We could not confirm Cary's rules for living in an RV or tiny home on a private lot. The only camping rule we found is a ban on camping within the village-owned park at Cary Lake, which does not address private land⁸. Illinois's campground statute covers licensed campgrounds, not living in an RV on your own lot¹⁵.

Because a use not listed as permitted in Cary's zoning table is not permitted¹, ask the Community Development Department in writing before you park an RV or place a tiny home on a lot³.

McHenry County's RV rules, which prohibit residential occupancy of an RV on property without an occupied dwelling, apply to unincorporated land, not to Cary¹⁶.

What are the steps to build a home in Cary, Illinois?

1. Confirm the lot's zoning district and that a home is a permitted use in the Table of Permitted Uses¹⁵.
2. Ask the Community Development Department about sewer and water service, since we could not confirm either for individual lots³.
3. If no sewer is available, start a septic site evaluation and permit with the McHenry County Department of Health¹³.
4. Apply for the building permit with the village. The village runs an online permit portal for some permit types and takes other applications by email at permits@caryillinois.com³.
5. Build to the 2021 International Residential Code with Cary's local amendments⁶.
6. Get a separate driveway permit⁷. If the driveway meets a McHenry County highway, the county's Division of Transportation requires its own access permit¹⁷; a state highway needs an Illinois Department of Transportation permit¹⁸.
7. Ask the village how inspections and the certificate of occupancy work. We could not confirm the steps, though the fee schedule lists a $50 certificate of occupancy fee¹².

What stays with McHenry County, and what to check before you buy in Cary?

Septic permits, and the county health department's role in wells and water, sit with McHenry County, not the village⁴. Illinois requires a permit before a new water well is built, from the Illinois Department of Public Health or an approved local health department¹⁹. Whether a lot inside Cary may use a private well is unconfirmed.

If the lot sits near a creek or wetland, state floodway and wetland authorizations may apply²⁰. We could not confirm Cary's own floodplain rules.

Property tax is a real cost here. McHenry County's effective property tax rate is 2.5%²¹, and the median bill is $7,153 a year²². For rules on land outside the village limits, see the McHenry County page.

Watch-outs

• The county's rules for unincorporated land do not apply inside Cary village limits; the village sets its own zoning and issues its own building permits¹².
• We could not confirm minimum lot sizes, setbacks, height limits, tiny-home rules or accessory dwelling rules for Cary's districts; ask the Community Development Department before you buy³.
• We could not confirm whether the village or the county handles septic review for lots inside Cary; ask the McHenry County Department of Health and the village before relying on a septic system¹³.
• Cary's code says uses not listed in the zoning table are not permitted, so a use you assume is fine, such as living in an RV, needs written confirmation first¹.

Sources

1. Cary Code Sec. 14.2.6 Use regulations (Village of Cary), quoted and re-checked
2. Cary Code Sec. 15.24.010 International Residential Code adopted (Village of Cary), quoted and re-checked
3. Village of Cary Community Development Department (building permits) (caryillinois.com)
4. So You Are Applying for a Septic Permit, quoted and re-checked
5. Cary Code Sec. 14.2.4 Zoning districts (Village of Cary), quoted and re-checked
6. Cary Code Sec. 15.24.010 International Residential Code adopted (Village of Cary), quoted and re-checked
7. Cary Code Sec. 15.24.010 International Residential Code adopted (Village of Cary), quoted and re-checked
8. Cary Code Sec. 18.01.080 Other park regulations (Village of Cary), quoted and re-checked
9. HB5913 Enrolled — Illinois Plumbing License Law amendment (Illinois statewide rule), quoted and re-checked
10. Village of Cary Planning & Zoning Division (caryillinois.com)
11. codelibrary.amlegal.com, quoted and re-checked
12. Cary Code Appendix A Fees, Rates, Penalties and Fines (Village of Cary), quoted and re-checked
13. McHenry County Department of Health, Environmental Health Division (mchenrycountyil.gov)
14. 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
15. Youth Camps and Campgrounds (Illinois statewide rule), quoted and re-checked
16. McHenry County Code § 16.56.050, Accessory Structure and Use Standards, quoted and re-checked
17. Highway Access Permit Application, quoted and re-checked
18. Highway Permits (Illinois statewide rule), quoted and re-checked
19. 77 Ill. Admin. Code 920.130, Water Well Permit Requirements (Illinois statewide rule), quoted and re-checked
20. Permit Application and Instructions (Illinois statewide rule), quoted and re-checked
21. Effective property tax rate: Bolthole Index county data
22. Median property tax bill: Bolthole Index county data

Written October 17, 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.