Zoning, building permits and septic rules in Mascoutah, Illinois

At a glance

Building permit

Issued by the City of Mascoutah Building and Zoning division¹

Zoning

City zoning under Chapter 34 of the city code (AG, RS-10, RS-8, RS-5, RMH, CF and others)²

Septic

Permit from the St. Clair County Health Department³

RV living

Not allowed: no recreational vehicle may be used as a dwelling⁴

Accessory dwelling

No accessory structure may be used as a dwelling⁵

Manufactured homes

Allowed with limits: HUD or Illinois seal required⁶

Minimum lot, AG district

3 acres⁷

Minimum lot, RS-10 district

10,000 square feet⁸

Who to call

Contact details are copied from each office’s official page and were checked against it on October 16, 2026.

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

Yes. The City of Mascoutah, in St. Clair County, zones land inside its limits through Chapter 34, the Unified Land Development Code, with districts such as AG, RS-10, RS-8, RS-5, RMH and CF². The city's Planning and Development division administers zoning, subdivision and site plan rules⁹.

Lot size depends on the district. In the AG agricultural district the minimum lot size is 3 acres⁷; in RS-10 single-family residential it is 10,000 square feet⁸. Both districts require a 25-foot front yard, a 10-foot side yard and a 25-foot rear yard¹⁰¹¹.

A recreational vehicle cannot be a home in Mascoutah: no recreational vehicle may be used as a dwelling⁴. No accessory structure, such as a detached garage or shed, may be used as a dwelling in any district⁵. We did not find a tiny-home rule; ask Planning and Development before buying with a tiny home in mind.

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

The City of Mascoutah's Building and Zoning division issues building permits for new construction and for certain remodeling projects inside city limits; the St. Clair County permit office is not the right counter for a Mascoutah address¹. Mascoutah has adopted the 2012 International Residential Code, with local amendments, for detached one- and two-family homes¹².

One-story detached sheds, playhouses and similar structures do not need a building permit when the floor area is within 200 square feet, and they must still meet city zoning¹. Residential plan review takes about one week¹. Before anyone occupies a new building, the building official must issue a certificate of occupancy¹. Outside construction hours start no earlier than 5:30 a.m.¹.

We could not confirm the permit fee schedule or an owner-builder exemption from the city's pages; ask the Building and Zoning division at the number below.

How do septic permits work inside Mascoutah?

The St. Clair County Health Department, not the City of Mascoutah, issues the permit for a private sewage system: before constructing or repairing one in St. Clair County, a permit must be obtained from the Health Department³. The application fee is $300.00 at submission³.

Private systems matter only where public sewer is not available. Where a public sewer becomes available, Mascoutah's code requires the building sewer to be connected within 60 days and the private system to be cleaned of sludge and filled¹³. Whether a particular address has sewer access is a question for the city's public works and utilities office at the city's main number.

We could not confirm well rules inside city limits; the Health Department is the office to ask.

Can you live in an RV, manufactured home or tiny home in Mascoutah?

RVs: no. No recreational vehicle may be used as a dwelling inside Mascoutah⁴. The city allows at most two RVs stored per lot, parked on residential driveways from April 1 through October 31 and in side and rear yards year-round, and none on city roads for more than 72 consecutive hours⁴.

Manufactured homes: allowed with conditions. A unit must bear the federal HUD seal or the Illinois seal, the RMH mobile home district has its own dimensional standards, and homes in the floodplain must meet elevation and anchoring rules⁶.

Tiny homes and temporary camping: we did not find a Mascoutah rule on either. Call Planning and Development before you buy.

Building a home in Mascoutah: the steps, in order

1. Confirm the lot's zoning district and minimum lot size with Planning and Development⁹.
2. Check whether the lot is in the floodplain; new buildings there must be protected to one foot above base flood elevation¹⁴.
3. Find out whether public sewer is available, or apply to the St. Clair County Health Department for a septic permit³.
4. Apply for a building permit from the City of Mascoutah Building and Zoning division¹.
5. Schedule inspections with the city; call as early as you can, since scheduling may take a few days¹.
6. Get a certificate of occupancy before moving in¹.

What stays with St. Clair County, and what to check before you buy near Mascoutah

Septic permits come from the St. Clair County Health Department, and the Health Department also reviews subdivisions served by private sewage systems³. Land outside Mascoutah city limits follows county rules, not the city's; see the St. Clair County page for unincorporated land. Dividing a parcel within 1 ½ miles of the city limits still needs a Mascoutah subdivision plat approved by the city council⁹.

St. Clair County's effective property tax rate is 2.1%¹⁵, with a median bill of $3,533 per year¹⁶. Floodplain lots add elevation requirements¹⁴.

Watch-outs

• Mascoutah's building permit and zoning rules apply only inside the city; land outside city limits follows St. Clair County rules, and a subdivision within 1 ½ miles of the city limits still needs city plat approval⁹.
• A storage shed is exempt from a building permit only up to 200 square feet and must still meet city zoning, so a larger shed needs a permit¹.
• We could not confirm Mascoutah's building permit fee schedule, whether homeowners can pull their own permits, or private well rules; call the Building and Zoning division¹ and the St. Clair County Health Department³.
• Floodplain lots need elevation or fill to one foot above base flood, and an RV kept on site more than 180 days a year may be treated as a building¹⁴.

Sources

1. City of Mascoutah Building and Zoning (mascoutah.org)
2. Mascoutah Code Sec. 34-3-5 Accessory uses and structures (Mascoutah), quoted and re-checked
3. St. Clair County Health Department – Water & Private Sewage (scchealthdept.com)
4. Mascoutah Code Sec. 34-9-21 Recreational vehicles (Mascoutah), quoted and re-checked
5. Mascoutah Code Sec. 34-3-5 Accessory uses and structures (Mascoutah), quoted and re-checked
6. Mascoutah Code Sec. 23-1-4 National safety standards (Mascoutah), quoted and re-checked
7. Mascoutah Code Sec. 34-5-7 AG dimensional regulations (Mascoutah), quoted and re-checked
8. Mascoutah Code Sec. 34-5-16 RS-10 dimensional regulations (Mascoutah), quoted and re-checked
9. City of Mascoutah Planning and Development (mascoutah.org)
10. Mascoutah Code Sec. 34-5-7 AG dimensional regulations (Mascoutah), quoted and re-checked
11. Mascoutah Code Sec. 34-5-16 RS-10 dimensional regulations (Mascoutah), quoted and re-checked
12. Mascoutah Code Sec. 6-1-2 Adoption of Residential Code (IRC 2012) (Mascoutah), quoted and re-checked
13. Mascoutah Code Sec. 38-5-17 Time constraints for public sewer (Mascoutah), quoted and re-checked
14. Mascoutah Code Sec. 14-1-7 Protecting buildings (Mascoutah), quoted and re-checked
15. Effective property tax rate: Bolthole Index county data
16. Median property tax bill: Bolthole Index county data

Written October 16, 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.