Bolthole Index

St. Louis County, Missouri

Zoning, building permits and septic rules in Hazelwood, Missouri

Hazelwood, Missouri (St. Louis County) runs its own zoning under Chapter 405 of the city code1, and the city's Building Department takes building permit applications online2. Electrical and plumbing permits are handled by St. Louis County under contract with the city2. We could not confirm who issues septic permits inside city limits, so ask St. Louis County Department of Public Health before you plan one3.

At a glance

Zoning
Hazelwood's own zoning ordinance (Chapter 405) applies inside city limits1
Building permits
City Building Department, applications online2
Electrical and plumbing permits
St. Louis County, under contract with the city2
R-1 minimum lot
1 acre, at least 70 feet wide4
NU Non-Urban minimum lot
3 acres per dwelling, at least 125 feet wide5
Septic permits
Not confirmed for city limits; ask St. Louis County Department of Public Health3
RV and tiny-home living
Not confirmed; ask the Building Department2

Who to call

Building permits

City of Hazelwood Building Department and Code Enforcement

Building permits and inspections inside Hazelwood city limits, residential occupancy permits and code enforcement

314-513-5034

inspections@hazelwoodmo.org

415 Elm Grove Lane Hazelwood, MO 63042

Online permits →

Septic permits

St. Louis County Department of Public Health

Septic (onsite wastewater) permitting in St. Louis County; confirm whether it applies inside Hazelwood

(314) 615-0600

administration.doh@stlouisco.com

6121 N Hanley Rd, Berkeley, MO 63134

Contact details are copied from each office’s official page and were checked against it on October 24, 2026.

Off-grid gear

Going off-grid in Hazelwood means bringing your own water and power. The kit we’d start with:

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Does Hazelwood, Missouri have zoning, and what does it mean for lot size and setbacks?

Yes. Hazelwood has its own zoning ordinance, Chapter 405 of the city code, and it applies inside Hazelwood city limits rather than the unincorporated county zoning1. The published districts include NU Non-Urban, R-1 through R-5 single-family districts, commercial, industrial and a historic overlay6.

Dimensions depend on the district. In R-1, every lot needs at least 1 acre and 70 feet of width4. R-1 homes need a front yard of at least 45 feet and side yards of at least 10 feet on each side7, and buildings may not exceed 2 stories or 35 feet, whichever is less8.

In the NU Non-Urban district, each dwelling needs at least 3 acres and 125 feet of width5. NU buildings may cover no more than 30% of an interior lot9. We could not confirm the rules for RVs, tiny homes or accessory dwellings, which sit in the zoning use regulations (1); ask the Building Department2.

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

Hazelwood's own Building Department handles building permit and inspection requests, and the city has moved all residential and commercial applications to an online portal2. The county's unincorporated-area permit rules do not apply inside the city; St. Louis County's code states that municipal zoning approval is needed where a municipality contracts with it10.

The city contracts with St. Louis County for electrical and plumbing permits and inspections2. We could not confirm the city's permit fees or exemptions from an official page. The Building Department publishes a residential permit fee table, so ask there before you budget2.

How do septic permits work inside Hazelwood?

We could not confirm who issues septic permits inside Hazelwood city limits. Missouri requires a construction permit before installing or repairing most onsite wastewater systems, though some single-family lots may be exempt11. In St. Louis County, the state lists the county plumbing department and Department of Public Health as the ordinance authorities, and incorporated areas may be handled differently12.

Before planning a septic system or well in Hazelwood, call St. Louis County Department of Public Health and ask whether a permit is needed and whether public sewer is required at your address3. Do not start work until a permit is issued or an exemption is confirmed13.

What are the steps to build a home in Hazelwood, in order?

  1. Identify your zoning district and read its Chapter 405 lot, setback and height rules6.
  2. Ask the Building Department what the city requires for your project, including any fee table2.
  3. Apply for the building permit through the city's online portal2.
  4. Request electrical and plumbing permits, which St. Louis County handles under contract2.
  5. Ask St. Louis County Department of Public Health about septic or sewer before you buy3.
  6. Check Chapter 410 if you plan to divide land; Hazelwood regulates subdivisions14.

What stays with St. Louis County, and what to check before you buy in Hazelwood?

St. Louis County handles electrical and plumbing permits for the city2. Septic is probably a county matter, but confirm it with the health department3. Missouri requires a permit for any development in a floodplain, so check the flood map for your lot first15. A driveway onto a state highway needs a MoDOT permit16.

For land outside Hazelwood in unincorporated areas, the rules differ; see the St. Louis County page. Farmland in the county averages $10,928 per acre17, and the county's effective property tax rate is 1.2%18.

Watch-outs

  • Hazelwood's zoning use regulations decide whether RVs, tiny homes and accessory dwellings are allowed, and we could not confirm them; ask the Building Department before buying2.
  • Structures built under St. Louis County rules before incorporation may continue, but additions may not extend past existing setbacks without a variance1.
  • Septic authority inside city limits is unconfirmed; call St. Louis County Department of Public Health before relying on any septic plan3.

Sources

  1. Hazelwood Code Chapter 405 Zoning Regulations, Article I (eCode360) (Hazelwood), quoted and re-checked
  2. City of Hazelwood Building Department and Code Enforcement (hazelwoodmo.org)
  3. St. Louis County Department of Public Health (stlouiscountymo.gov)
  4. Hazelwood Code Chapter 405 Zoning Regulations, district regulations (eCode360) (Hazelwood), quoted and re-checked
  5. Hazelwood Code Chapter 405 Zoning Regulations, district regulations (eCode360) (Hazelwood), quoted and re-checked
  6. Hazelwood Code Chapter 405 Zoning Regulations, district regulations (eCode360) (Hazelwood), quoted and re-checked
  7. Hazelwood Code Chapter 405 Zoning Regulations, district regulations (eCode360) (Hazelwood), quoted and re-checked
  8. Hazelwood Code Chapter 405 Zoning Regulations, district regulations (eCode360) (Hazelwood), quoted and re-checked
  9. Hazelwood Code Chapter 405 Zoning Regulations, district regulations (eCode360) (Hazelwood), quoted and re-checked
  10. Chapter 1115 - Building Code, quoted and re-checked
  11. OWTS Construction Permit Process (Missouri statewide rule), quoted and re-checked
  12. OWTS Construction Permit Process — St. Louis County authorities, quoted and re-checked
  13. OWTS Construction Permit Process, quoted and re-checked
  14. City of Hazelwood, MO code of ordinances table of contents (eCode360) (Hazelwood), quoted and re-checked
  15. Floodplain Forms (Missouri statewide rule), quoted and re-checked
  16. Permits | Missouri Department of Transportation (Missouri statewide rule), quoted and re-checked
  17. Farmland value per acre (USDA census): Bolthole Index county data
  18. Effective property tax rate: Bolthole Index county data

Written October 24, 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.

Answers from the rulebook for Hazelwood

Hazelwood’s own rules

  • Local zoningPresent (with conditions)

    Land inside Hazelwood city limits (St. Louis County, Missouri). Hazelwood's own Chapter 405 zoning ordinance applies; it does not govern unincorporated St. Louis County.

    • Use permissions are set in Chapter 405 Appendix A (use regulations), which was not opened for this record.
    • Structures built under St. Louis County rules before incorporation may continue, but structural alterations or additions may not extend beyond existing setbacks without a variance (Chapter 405 district sections).
    “this chapter and any amendments thereto shall be known, cited and referred to as the zoning ordinance of the city of hazelwood, missouri.”
  • Zoning districtsPublished (with conditions)

    Zoning districts inside Hazelwood city limits.

    • Districts seen in the text: NU Non-Urban (Sec. 405.145), R-1 (405.150), R-2 (405.155), R-3 (405.160), R-4, R-5 (405.170), C-2 (405.185), C-3 (405.190), I-1 (405.195), HD historic overlay (405.210). R-1 through R-5 are single-family districts.
    • Appendix C is said to summarize area, setback and height by district; it was not opened.
    “section 405.150 "r-1" single-family dwelling district. [ord. no. 3674-05 §§1—3, 8-17-2005]”
  • Minimum lot sizeSpecified

    R-1 single-family dwelling district (Section 405.150) inside Hazelwood city limits.

    • Lot width minimum is 70 feet, per the same subsection.
    • Lot-of-record exceptions for R-1 were not verified.

    minimum lot area: >= 1 acre · minimum lot width: >= 70 feet

    “every lot or tract of land shall have an area of not less than one (1) acre (forty-three thousand five hundred sixty (43,560) square feet).”
    One more reviewed finding on this topic
    • Specified — NU Non-Urban district (Section 405.145), the agricultural/rural-residential district, inside Hazelwood city limits.
      “for each dwelling and buildings accessory thereto, there shall be a lot area of not less than three (3) acres (one hundred thirty thousand six hundred eighty (130,680) square feet).”
  • SetbacksDistrict specific (with conditions)

    R-1 single-family dwelling district (Section 405.150) inside Hazelwood city limits.

    • Front yard can be reduced where 40% or more of the same-side frontage has a built front yard line within 10 feet (not reproduced here).
    • Side yard reduction for lots of record 50 feet wide or less is not reproduced here.

    front yard depth: >= 45 feet (unless 40% or more of same-side frontage is built to an observed front yard line within 10 feet) · side yard width: >= 10 feet (lots of record 50 feet wide or less may reduce to 10% of lot width, minimum 4 feet) · rear yard depth: >= 30 feet (or 20% of lot depth, whichever is larger, not exceeding 40 feet)

    “there shall be a side yard on each side of the building having a width of not less than ten (10) feet.”
    One more reviewed finding on this topic
    • District specific (with conditions) — NU Non-Urban district (Section 405.145), the agricultural/rural-residential district, inside Hazelwood city limits.
      “there shall be a side yard on each side of the main building of not less than twenty (20) feet for dwellings of one (1) story and of not less than thirty-five (35) feet for dwellings of more than one (1) story.”
  • Lot coverageSpecified

    NU Non-Urban district (Section 405.145), inside Hazelwood city limits.

    • Accessory buildings may not cover more than 20% of the rear yard.
    • Percentages are of lot area for main and accessory buildings and accessory structures.

    structure coverage, interior lot: <= 30 percent of lot area · structure coverage, corner lot: <= 35 percent of lot area

    “main and accessory buildings and/or accessory structures shall not cover more than thirty percent (30%) of the lot area on interior lots and thirty-five percent (35%) of the lot area on corner lots; accessory buildings shall not cover more than twenty percent (20%) of the rear yard.”
  • Building heightSpecified

    R-1 single-family dwelling district (Section 405.150) inside Hazelwood city limits.

    • Exceptions in article IX, section 405.335 apply.

    building height: <= 35 feet (whichever is lesser of 2 stories or 35 feet; article IX, section 405.335 exceptions) · building height: <= 2 stories (whichever is lesser of 2 stories or 35 feet)

    “no building shall exceed two (2) stories or thirty-five (35) feet in height, whichever is lesser of the two (2), except as provided in article ix, section 405.335 of this chapter.”
  • Subdividing landRegulated (with conditions)

    Land divisions inside Hazelwood city limits under Chapter 410.

    • Chapter 410 text (approval steps, lot standards) was not opened.
    “chapter 410 subdivisions, streets and land development (section 410.010”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Hazelwood or St. Louis County directly.

  • Building permit — Building permits for construction inside Hazelwood city limits.
  • Owner-builder exemption — Owner-builder permits inside Hazelwood city limits.
  • Building code adopted — Building codes inside Hazelwood city limits.
  • Inspections — Building inspections inside Hazelwood city limits.
  • Certificate of occupancy — Certificates of occupancy inside Hazelwood city limits.
18 more unanswered
  • Minimum dwelling size
  • Living in an RV
  • Camping on your land
  • Tiny homes
  • Manufactured homes
  • Accessory dwellings
  • Who permits septic
  • Septic permit
  • Septic inspection
  • Off-grid sanitation
  • Well permit
  • Mandatory utility hookup
  • Agricultural exemption
  • Driveway access
  • Building in a floodplain
  • Short-term rentals
  • Permit fees
  • Permit process

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Unanswered questions are usually a sign that Hazelwood publishes no rule on the point, not that none exists. St. Louis County’s page lists the county offices to call.

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