St. Mary Parish, LA: Owner-Builder Allowed

Unincorporated St. Mary Parish, Louisiana requires building permits for regulated construction; Planning & Zoning directs applications to MGO Connect, but the complete permit requirements and exceptions remain unconfirmed¹. The parish Unified Development Code governs zoning and subdivision on unincorporated land². Septic approval comes from the Louisiana Department of Health, Office of Public Health, with local assistance through the St. Mary Parish Health Unit^3,4.

At a glance

Building permit: Required for regulated construction; ask Planning & Zoning which work needs approval¹
Zoning: Yes on unincorporated parish land²
Septic permit: Required from the Louisiana state health officer; the parish health unit's sanitarians run the local process^4,5
RV living: Private-land occupancy rule not confirmed; ask Planning & Zoning²
Tiny home: District standards may control size, placement and use⁶
Owner-builder: Conditional contractor-licensing exemption; permits and safety codes still apply⁷
Private well: Licensed driller and state registration required; domestic wells follow post-installation notice rules⁸

Who to call

Planning & zoning

St. Mary Parish Planning & Zoning Department

Parish permit applications and Planning & Zoning questions

(337) 828-4100 ext. 5280

permits@stmaryparishla.gov

Fifth Floor Courthouse, Franklin, LA 70538

Online permits →

Septic permits

St. Mary Parish Health Unit

Local Environmental Health contact for St. Mary Parish

985.380.2441

1200 David Drive, Morgan City, LA 70380

Contact details are copied from each office’s official page and were checked against it on October 26, 2026.

Do you need a building permit in St. Mary Parish, Louisiana?

St. Mary Parish requires building permits for regulated construction, but we could not confirm the complete parish rule identifying covered projects and exemptions; ask Planning & Zoning about your proposed work¹. Louisiana’s State Uniform Construction Code applies in St. Mary Parish, with mandatory residential-code enforcement for new construction, reconstruction, additions to homes previously built to that code and extensive alterations^9,10. Extensive alterations cover work areas exceeding 50% of the dwelling-unit area⁹. Required building inspections must be conducted by a building-code enforcement officer or certified third-party provider, with the inspector on site except for roofing inspections¹¹. The parish and its cities must enforce only the State Uniform Construction Code and use code enforcement officers or certified third-party providers, so the parish cannot add its own building code¹⁰.

Who issues building permits in St. Mary Parish, Louisiana, and how do you reach them?

For unincorporated land, start with St. Mary Parish Planning & Zoning: (337) 828-4100 ext.

For unincorporated land, start with St. Mary Parish Planning & Zoning: (337) 828-4100 ext. 5280, permits@stmaryparishla.gov, Fifth Floor Courthouse, Franklin, LA 70538¹. Applications go through MGO Connect, but the full review, inspection, fee and approval procedure remains unconfirmed; request the project checklist before work begins¹. Morgan City and Franklin issue their own building permits inside city limits^12,13. Patterson has a municipal application process for covered exterior work in its historic district¹⁴. Septic approval stays with the Louisiana Department of Health, Office of Public Health, including inside municipalities³.

Does St. Mary Parish have zoning?

St. Mary Parish’s Unified Development Code governs zoning, subdivision and development decisions on all unincorporated land.

St. Mary Parish’s Unified Development Code governs zoning, subdivision and development decisions on all unincorporated land². The parish zoning map is available, but we could not confirm district-specific setbacks, height, lot coverage, minimum lot size or dwelling-size standards; ask Planning & Zoning for the parcel’s district and requirements^1,2. The same Unified Development Code regulates subdivision of unincorporated land, so splitting a tract for sale or for a second home goes through the parish; we could not confirm the thresholds, procedures or fees². Morgan City, Franklin, Patterson and Berwick set their own zoning inside municipal limits^15,16,17,18. Municipal zoning does not transfer septic approval from the Louisiana Department of Health, Office of Public Health³.

How do septic permits work in St. Mary Parish, Louisiana?

Louisiana, rather than the parish government, regulates individual sewerage systems: no one may install, alter or operate one without first obtaining a permit from the state health officer.

Louisiana, rather than the parish government, regulates individual sewerage systems: no one may install, alter or operate one without first obtaining a permit from the state health officer^3,5. State review includes the plans and considers whether connection to community sewer is feasible, along with soil, drainage, lot dimensions and health risks⁵. Final approval requires compliance verification through an on-site state inspection, an installer certification or both, and the installer certification is due within 15 days after completion⁵. The Louisiana Department of Health describes sanitarians in each parish health unit as the staff who inform, advise and operate the onsite sewage permitting system, and the local service for St. Mary Parish runs through the St. Mary Parish Health Unit in Morgan City; the parish government is not the septic permitting authority^4,19. Ask the St. Mary Parish Health Unit for the application and site-evaluation steps¹⁹. USDA soil data rates 0% of parish soils as free of severe limitations for a conventional drain field; that rating makes an early site evaluation essential but does not by itself prove that a parcel cannot support an approved system²⁰.

Can you live in an RV or tiny home on your land in St. Mary Parish?

We could not confirm whether unincorporated St. Mary Parish allows long-term RV occupancy, temporary private-land camping or tiny-home occupancy; ask Planning & Zoning about the proposed use.

We could not confirm whether unincorporated St. Mary Parish allows long-term RV occupancy, temporary private-land camping or tiny-home occupancy; ask Planning & Zoning about the proposed use¹. The parish has zoning on unincorporated land, and Louisiana's framework leaves dwelling size, setbacks and similar standards to local zoning districts^2,6. A tiny home therefore still needs a district and code review, while an RV question needs a direct parcel-specific answer from Planning & Zoning¹. Before buying, give Planning & Zoning the parcel number and describe whether the unit is temporary, connected to utilities or intended as a full-time dwelling¹.

What are the steps to build a home in St. Mary Parish, Louisiana?

Ask St. Mary Parish Planning & Zoning to confirm jurisdiction, the mapped zoning district and the applicable dimensional standards.

Ask St. Mary Parish Planning & Zoning to confirm jurisdiction, the mapped zoning district and the applicable dimensional standards^1,2.

Confirm sewer availability; if an individual system is needed, start state health review before fixing the house location⁵.

Submit the planning and zoning permit application through MGO Connect and ask for the current fee, plan and inspection checklist¹.

If supervising construction of your personal residence, ask Planning & Zoning for the required contractor-licensing exemption affidavit before permit issuance⁷. The exemption covers construction on your own property for your own use, not for sale or rent, and it generally allows 1 residence per year, measured from certificate-of-occupancy issuance, with exceptions for a change in legal marital status or an employment relocation exceeding 50 miles; health and life-safety codes still apply⁷. A farmer building for agricultural purposes on owned or leased land may also have a contractor-licensing exemption, but it does not waive health or life-safety requirements²¹.

Obtain a signed, numbered LaDOTD access permit before constructing a connection to a state highway²².

Complete required building inspections and obtain final septic verification before occupancy^5,11.

What should you check before buying land in St. Mary Parish?

Check septic feasibility first: 0% of mapped parish soils rate as free of severe limitations for a conventional drain field, so an inexpensive parcel may need a costlier approved system.

Check septic feasibility first: 0% of mapped parish soils rate as free of severe limitations for a conventional drain field, so an inexpensive parcel may need a costlier approved system²⁰. Check flood status and elevation next; development in a regulatory floodway needs a no-rise certification before permitting under the statewide floodway standard, and ask Planning & Zoning to identify the local floodplain administrator and elevation requirements^1,23. Verify legal road access and determine whether a driveway meets a parish road or a state highway, because state-highway connections require LaDOTD approval²². If planning a well, Louisiana requires a licensed driller and state registration, with domestic wells following the applicable post-installation notification rule⁸. Finally, price insurance for the parcel: the typical annual premium is about $3,051, while the effective property-tax rate is about 0.4% and the median annual bill is about $515²⁰.

Watch-outs

St. Mary Parish’s MGO Connect link does not establish which projects require building permits or provide the full fee, review and inspection procedure; request the checklist from Planning & Zoning¹.
A state septic permit is required before installing, altering or operating an individual sewerage system, and parish soils commonly pose severe conventional-drain-field limitations^5,20.
Private-land RV and tiny-home occupancy rules remain unconfirmed; ask Planning & Zoning for a written parcel-specific answer¹.

Sources

23 official pages, each quoted and re-checked · written October 26, 2026

Written October 26, 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.

Off-grid gear

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

These are affiliate links — we may earn a commission, at no cost to you. As an Amazon Associate, Bolthole Index earns from qualifying purchases.

Compared with neighboring counties

Like all 6 of its neighbors, St. Mary Parish requires a building permit for a home.

Rule	St. Mary Parish	Assumption Parish	Iberia Parish	Terrebonne Parish	St. James Parish	Iberville Parish	Ascension Parish
Building permit	Required	Required	Required	Required	Required	Required	Required
County zoning	Yes	No	Yes	Yes	Yes	Yes	Yes
Septic permits	LA Dept. of Health	LA Dept. of Health	LA Dept. of Health	LA Dept. of Health	LA Dept. of Health	LA Dept. of Health	LA Dept. of Health

Cities and towns in St. Mary Parish

Inside a city or town, that city usually issues building permits and sets zoning; the county’s rules above cover unincorporated land. Septic, wells and floodplain rules usually stay with the county or state everywhere.

Not yet covered: Town of Baldwin

Answers from the rulebook for St. Mary Parish

What the ordinances and state agencies actually say — one answer per question, each quoted from the official source and independently re-checked.

St. Mary Parish rules

County-wide zoningPresent (with conditions)
Zoning and development regulation in unincorporated St. Mary Parish.
- The UDC applies to all unincorporated lands; incorporated municipalities may have separate rules.
“Accordingly, this UDC applies to all unincorporated lands within St. Mary Parish and includes regulatory prvosions for all zoning, subdivision, and other development-related decisions.”
Unified Development Ordinance ↗Re-checked Sep 30, 2026
Local zoningPresent (with conditions)
Parish-administered zoning in unincorporated St. Mary Parish.
- The UDC applies to unincorporated lands; this claim does not determine zoning in incorporated municipalities.
“Accordingly, this UDC applies to all unincorporated lands within St. Mary Parish and includes regulatory prvosions for all zoning, subdivision, and other development-related decisions.”
Unified Development Ordinance ↗Re-checked Sep 30, 2026
Zoning districtsPublished (with conditions)
St. Mary Parish zoning districts and map for unincorporated lands.
- The UDC landing page directs users to view the Parish zoning map; district-specific dimensional rules were not extracted in this run.
“To search, browse, or print the provisions of this UDC, or view the Parish's zoning map, use the buttons at the top of this page.”
Unified Development Ordinance ↗Re-checked Sep 30, 2026
Subdividing landRegulated (with conditions)
Subdivision and other development-related decisions in unincorporated St. Mary Parish.
- The cited UDC landing page states that it applies to all unincorporated lands.
- Specific subdivision procedures, thresholds, exceptions, and fees were not resolved.
“Accordingly, this UDC applies to all unincorporated lands within St. Mary Parish and includes regulatory prvosions for all zoning, subdivision, and other development-related decisions.”
Unified Development Ordinance ↗Re-checked Sep 30, 2026
One more reviewed finding on this topic
- Regulated (with conditions) — Subdivision and development decisions in unincorporated St. Mary Parish.
  “Accordingly, this UDC applies to all unincorporated lands within St. Mary Parish and includes regulatory prvosions for all zoning, subdivision, and other development-related decisions.”
  Unified Development Ordinance ↗Re-checked Sep 30, 2026
Permit processPartial
Planning and zoning permit applications handled by St. Mary Parish.
- The page identifies the Planning & Zoning Department and directs applicants to MGO Connect for complete permit applications.
- The page does not state the full review, inspection, fee, or approval procedure.
“St. Mary Parish Unified Development Code: http://online.encodeplus.com/regs/stmary-la/ Complete Permit Applications at: http://www.mgoconnect.org”
Planning & Zoning Department - St. Mary Parish Government ↗Re-checked Sep 29, 2026
One more reviewed finding on this topic
- Published (with conditions) — St. Mary Parish planning and zoning permit process.
  “Complete Permit Applications at: http://www.mgoconnect.org”
  Planning & Zoning Department ↗Re-checked Sep 30, 2026

Louisiana rules that apply here

Building permitRequired
Construction subject to Louisiana’s State Uniform Construction Code, including mandatory residential-code-covered new construction, reconstruction, additions to homes previously built to the International Residential Code, and extensive alterations.
- Municipalities and parishes administer permit issuance and may use certified third-party providers.
- The cited residential-code enforcement mandate applies to new construction, reconstruction, additions to homes previously built to the International Residential Code, and extensive alterations.
- Local permitting procedures and code enforcement remain administered by the applicable municipality or parish.
extensive alteration threshold: > 50 percent of dwelling-unit area (The statute defines an extensive alteration as an alteration when the total area of all work areas exceeds fifty percent of the dwelling unit.)
“Enforcement procedures by building code enforcement officers [...] shall include examination or review of plans, drawings, or specifications; [...] and the issuance, denial, or revocation of permits.”
Louisiana Revised Statutes 40:1730.23 — Enforcement of building codes by municipalities and parishes ↗Re-checked Sep 9, 2026
One more reviewed finding on this topic
- Limited — Construction subject to Louisiana State Uniform Construction Code enforcement by Louisiana parishes and municipalities.
  “Enforcement procedures by building code enforcement officers or third-party providers acting in the capacity of a building code enforcement officer shall include examination or review of plans, drawings, or specifications; the conducting of inspections; and the issuance, denial, or revocation of permits.”
  R.S. 40:1730.23 — Enforcement of building codes by municipalities, parishes, and the fire marshal ↗Re-checked Sep 26, 2026
Owner-builder exemptionConditional
Owners of property supervising or assuming charge of construction, alteration, repair, improvement, movement, demolition, erection, or maintenance of their personal residence in Louisiana under the contractor-licensing exemption in La. R.S. 37:2157(A)(13).
- The residence must be the homeowner's personal residence and the homeowner may not build more than one residence per year.
- The one-year period commences on the date the certificate of occupancy is issued.
- An owner may build more than one single-family dwelling during a one-year period only when an additional residence results from a change in the owner's legal marital status or employment status requiring relocation to another employment location more than fifty miles from the owner's personal residence.
- An affidavit of exemption on a form provided by the Louisiana State Licensing Board for Contractors must be provided to obtain the building permit.
- The owner-builder affidavit states that the house must be maintained as the owner's primary residence after issuance of the certificate of occupancy or completion of construction.
- The exemption does not exempt licensable subcontractors from applicable licensure requirements.
- Local and state health and life-safety code requirements continue to apply.
- The official sources do not state a fee for the exemption or affidavit.
maximum residences: 1 residence per one-year period (Additional single-family dwelling allowed when a change in legal marital status or employment status requires relocation more than 50 miles from the owner's personal residence.) · relocation distance: > 50 miles (Applies to the employment-relocation exception.) · one-year period start: date of issuance of certificate of occupancy
“Owners of property who [...] assume charge of the construction [...] of their personal residences, if the homeowner does not build more than one residence per year.”
Louisiana Revised Statutes § 37:2157 — Exemptions ↗Re-checked Sep 26, 2026
2 more reviewed findings on this topic
- Available (with conditions) — A property owner in St. Mary Parish who supervises, directs, or assumes charge of construction of the owner's personal residence, subject to Louisiana's statutory conditions and the local permitting process.
  “Owners of property who supervise [...] their personal residences, if the homeowner does not build more than one residence per year.”
  Louisiana Revised Statutes § 37:2157 — Exemptions ↗Re-checked Sep 24, 2026
- Available (with conditions) — Owner-supervised construction and related residential-contractor licensure exemptions that may apply in St. Mary Parish.
  “Owners of property who supervise, superintend, oversee, direct, or in any manner assume charge of the construction, alteration, repair, improvement, movement, demolition, putting up, tearing down, or maintenance of their personal residences, if the homeowner does not build more than one residence per year.”
  legis.la.gov ↗Re-checked Sep 26, 2026
Building code adoptedAdopted (with conditions)
Construction in St. Mary Parish under the Louisiana State Uniform Construction Code, including the state-adopted International Building Code, International Existing Building Code, International Residential Code, International Mechanical Code, International Plumbing Code, International Fuel Gas Code, International Energy Conservation Code, and National Electric Code.
- Louisiana municipalities and parishes must enforce only the construction codes provided in the State Uniform Construction Code and must use building-code enforcement officers or certified third-party providers.
- The International Residential Code standards are mandatory only for new construction, reconstruction, additions to homes previously built to the International Residential Code, and extensive alterations; a municipality, parish, or regional planning commission may enforce Appendix J at its option.
- An extensive alteration means an alteration in which the total area of all work areas exceeds fifty percent of the area of the dwelling unit.
- The council may adopt code appendices only when the specific appendix is identified by name or letter designation; Appendix J is not adopted by the council and may be adopted and enforced only at the option of a parish, municipality, or regional planning commission.
- No municipality or parish may adopt or enforce an ordinance or regulation requiring a fire-protection sprinkler system in one- or two-family dwellings.
- Manufactured-home construction is governed by applicable federal manufactured-housing standards or state installation standards and the Louisiana Manufactured Housing Commission; the exemption includes driveways, steps, decks, and similar accessory structures but excludes additional living area or other heated and cooled space outside the original footprint.
- The initial State Uniform Construction Code became effective January 1, 2007. The cited statute includes amendments effective July 1, 2026.
- Enforcement procedures include plan review, inspections, and issuance, denial, or revocation of permits; applicable conflict-of-interest restrictions apply to enforcement officers and third-party providers.
“all municipalities and parishes in this state shall enforce only the construction codes provided for in this Part.”
RS 40:1730.28. Mandatory adoption of certain nationally recognized codes and standards as the state uniform construction code; adoption by reference ↗Re-checked Sep 30, 2026
6 more reviewed findings on this topic
- Adopted (with conditions) — Louisiana construction subject to the State Uniform Construction Code, including St. Mary Parish.
  “Except as provided in Subsection C of this Section, the council shall evaluate, adopt, and amend only the latest editions of the following as the State Uniform Construction Code:”
  RS 40:1730.28 - Louisiana State Legislature ↗Re-checked Sep 29, 2026
- Adopted (with conditions) — Louisiana construction subject to the State Uniform Construction Code, including St. Mary Parish.
  “Except as provided in Subsection C of this Section, the council shall evaluate, adopt, and amend only the latest editions of the following as the State Uniform Construction Code:”
  R.S. 40:1730.28 — Mandatory adoption of nationally recognized codes ↗Re-checked Sep 30, 2026
- Adopted (with conditions) — Construction regulated by the Louisiana State Uniform Construction Code statewide.
  “The commission shall evaluate, adopt, and amend only the latest editions of all of the following as the Uniform Construction Code:”
  Louisiana Revised Statutes § 40:1730.28 ↗Re-checked Sep 9, 2026
- Partial — The Louisiana State Uniform Construction Code's statewide adoption of the International Building Code and its referenced standards for construction in Louisiana.
  “(1) International Building Code, not including Parts I-Administrative, and Chapter 27-Electrical. The applicable standards referenced in that code are included for regulation of construction within this state. The appendices of that code may be adopted as needed, but the specific appendix or appendices shall be referenced by name or letter designation at the time of adoption.”
  Louisiana Revised Statutes § 40:1730.28 ↗Re-checked Sep 26, 2026
- Adopted — The Louisiana State Uniform Construction Code, including the International Residential Code, applies statewide to regulated construction, including new residential construction, reconstruction, additions to homes previously built to the International Residential Code, and extensive alterations.
  “The applicable standards referenced in that code are included for regulation of construction within this state.”
  RS 40:1730.28. Mandatory adoption of nationally recognized codes and standards as the state uniform construction code ↗Re-checked Sep 26, 2026
- Adopted — The Louisiana State Uniform Construction Code, including the International Residential Code, regulates construction statewide and applies to new residential construction, reconstruction, additions to homes previously built to the code, and extensive alterations.
  “The International Residential Code, not including Part I-Administration and VIII-Electrical. The applicable standards referenced in that code are included for regulation of construction within this state. The enforcement of such standards shall be mandatory only with respect to new construction, reconstruction, additions to homes previously built to the International Residential Code, and extensive alterations; however, a municipality, parish, or regional planning commission may enforce Appendix J of the code at its option.”
  RS 40:1730.28 — Mandatory adoption of nationally recognized codes and standards as the state uniform construction code ↗Re-checked Sep 26, 2026
InspectionsRequired
Commercial and residential structures subject to Louisiana State Uniform Construction Code enforcement.
- Inspections are conducted by a building code enforcement officer or certified third-party provider.
- Except for roofing inspections, the inspector or provider must be present on site.
- A certified third-party provider may accept location-verified geotagged photographs or videos for required roofing and reroofing inspections.
- The parish, municipality, regional planning commission, or third-party provider administering the inspection may prescribe lawful fees.
“For purposes of code enforcement pursuant to this Section, a building code enforcement officer or a certified third-party provider shall conduct all inspections of any commercial or residential structure and for all inspections, other than roofing inspections, shall be present on site for such inspections.”
R.S. 40:1730.23 — Enforcement of building codes by municipalities, parishes, and the fire marshal ↗Re-checked Sep 26, 2026
2 more reviewed findings on this topic
- Required — Commercial and residential structures subject to Louisiana building-code enforcement.
  “For purposes of code enforcement pursuant to this Section, a building code enforcement officer or a certified third-party provider shall conduct all inspections of any commercial or residential structure and for all inspections, other than roofing inspections, shall be present on site for such inspections.”
  R.S. 40:1730.23 — Enforcement of building codes by municipalities and parishes ↗Re-checked Sep 30, 2026
- Required — Inspections of residential structures for allowing occupancy or reconnecting utilities, and inspections performed under Louisiana State Uniform Construction Code enforcement.
  “an inspector shall conduct a building inspection using the requirements of the codes in effect for the locality”
  Louisiana Revised Statutes 40:1730.23 — Enforcement of building codes by municipalities and parishes ↗Re-checked Sep 9, 2026
Certificate of occupancyLimited
New residential construction in a parish or municipality enforcing the Louisiana State Uniform Construction Code, particularly where a residential mortgage lender is involved.
- The statute expressly addresses a certificate of occupancy issued by a local building official or third-party provider for new residential construction.
- Upon receipt of that certificate, a lender providing a residential mortgage loan must file a copy in the parish conveyance records.
- The homeowner must provide the lender a copy.
- The lender may assess only a reasonable filing charge not exceeding the amount charged by the parish for filing the document.
- If the construction-code provisions cease to be enforced in a parish, the statutory filing provisions become null and void there.
- In areas where windblown-debris storm shutters are required, occupancy may be allowed upon an affidavit that the owner ordered the shutters; installation must occur within ninety days, followed by notification and final inspection.
storm-shutter installation deadline: 90 days (Applies when occupancy is allowed under the storm-shutter affidavit provision.)
“Upon receipt of the certificate of occupancy issued by a local building official or third-party provider for a new residential construction, a lender who provides a residential mortgage loan for the purchase of such new residential construction shall file a copy of the certificate of occupancy in the conveyance records of the parish where the new residential construction is located.”
R.S. 40:1730.23 — Enforcement of building codes by municipalities, parishes, and the fire marshal ↗Re-checked Sep 26, 2026
One more reviewed finding on this topic
- Required — State-owned buildings in Louisiana.
  “The occupancy permit will be issued to the using agency when the building construction has been approved by the state fire marshal”
  Louisiana Revised Statutes 40:1724 — Building permits and occupancy permits ↗Re-checked Sep 9, 2026
Minimum dwelling sizeDistrict specific (with conditions)
Municipal zoning districts in Louisiana; the state authorizes municipalities to regulate the size of structures, which may include dwelling-size standards, but does not establish one statewide minimum dwelling size in this provision.
- Any actual minimum dwelling-size requirement must be found in the applicable municipality's zoning ordinance or district regulations.
- Local zoning ordinances remain subject to the judicial-review standards stated in the statute.
“size of structures”
RS 33:4721 — Regulation of size and use of buildings ↗Re-checked Sep 9, 2026
Minimum lot sizeSpecified
Certain subdivisions outside incorporated areas consisting of single-family lots owned by one owner or co-owners, subject to the parish and population exclusions in R.S. 33:106.1(A).
- Minimum lot area is 22,500 square feet.
- Minimum frontage is 125 feet.
- For nonrectangular lots with less than 125 feet frontage, average width must be 125 feet and frontage must be at least 60 feet.
- Lots must support sewage-disposal systems and individual water systems meeting Louisiana Department of Health suitability requirements.
- The statutory planning-commission exemption does not apply in the parishes listed in R.S. 33:106.1(A), municipalities within those parishes, or jurisdictions with a population greater than 300,000.
- The exemption preserves planning-commission authority over utilities, drainage, sewerage disposal, and street-planning dimensions, composition, and alignment.
minimum lot area: >= 22500 square feet · minimum frontage: >= 125 feet (Nonrectangular lots may have less than 125 feet frontage only if average width is 125 feet and frontage is at least 60 feet.)
“minimum square footage of twenty-two thousand five hundred square feet, with a minimum width of one hundred twenty-five feet of frontage”
RS 33:106.1 — Planning commissions; exempt subdivisions; septic tanks and field drains permitted ↗Re-checked Sep 9, 2026
SetbacksDistrict specific (with conditions)
Municipal zoning districts in Louisiana; municipalities may regulate the size of yards, courts, and other open spaces, which can include setbacks.
- The applicable setback is determined by the local zoning ordinance and district.
- No statewide numerical setback is established by the cited statute.
“size of yards, courts, and other open spaces”
RS 33:4721 — Regulation of size and use of buildings ↗Re-checked Sep 9, 2026
Lot coverageDistrict specific (with conditions)
Municipal zoning districts in Louisiana; municipalities may regulate the percentage of a lot that may be occupied.
- The applicable lot-coverage percentage is determined by the local zoning ordinance and district.
- No statewide numerical lot-coverage limit is established by the cited statute.
“percentage of lot that may be occupied”
RS 33:4721 — Regulation of size and use of buildings ↗Re-checked Sep 9, 2026
Building heightDistrict specific (with conditions)
Municipal zoning districts in Louisiana; municipalities may regulate building height and number of stories.
- The applicable height limit is determined by the local zoning ordinance and district.
- No statewide numerical building-height limit is established by the cited statute.
“height, number of stories”
RS 33:4721 — Regulation of size and use of buildings ↗Re-checked Sep 9, 2026
Manufactured homesLimited
Installation of manufactured or modular homes in Louisiana; this is a statewide installation condition and does not determine whether a particular parish or municipality permits residential occupancy at a particular site.
- An installer or homeowner must first obtain an installation permit sticker from the commission.
- The sticker must be affixed to the side of the home at the electrical-power connection point.
- The sticker must be affixed within ten days of delivery unless extenuating circumstances are shown.
- The installation must comply strictly with Part XIV.
- A person other than the homeowner or a licensed installer may not perform an installation; community owners and park operators are not homeowners when the home is or will be leased.
- The statute states a $20 installation-permit-sticker fee.
installation permit sticker fee: 20 USD · sticker affixing deadline: <= 10 days after delivery (unless extenuating circumstances are shown)
“Any installer or homeowner installing a manufactured or modular home in this state shall first obtain an installation permit sticker from the commission”
Louisiana Revised Statutes 51:912.27, Licensure of installers and transporters; adoption of rules; compliance with installation instructions; disposition of fees; continuing education; bond ↗Re-checked Nov 4, 2026
Who permits septicState
Individual onsite sewage treatment and disposal systems serving property in St. Mary Parish.
- The Louisiana Department of Health, Office of Public Health, has authority over treatment and disposal of municipal or domestic sewage.
- A parish, municipality, or planning commission may not authorize installation of individual sewage treatment and disposal systems without written approval from the Office of Public Health.
- State rules require sanitary-sewage rules and regulations and submission of sewerage-work plans for review and approval to the state health officer or designee.
- Health permits may be issued through state-employed licensed sanitarians or licensed sanitarians of parish health units or departments.
“The state health officer and the office of public health of the Louisiana Department of Health shall have exclusive jurisdiction, control, and authority: [...] (9) Over the treatment and disposal of municipal or domestic sewage.”
RS 40:5. General powers and jurisdiction ↗Re-checked Oct 6, 2026
2 more reviewed findings on this topic
- State (with conditions) — Onsite sewage treatment permitting and administration applicable in St. Mary Parish, including service through the parish health unit.
  “A person shall not install, cause to be installed, alter subsequent to installation, or operate an individual sewerage system of any kind without first having obtained a permit from the State Health Officer.”
  Onsite Wastewater Program ↗Re-checked Oct 7, 2026
- State — Statewide regulation of individual sewerage systems in Louisiana.
  “A person shall not install, cause to be installed, alter subsequent to installation, or operate an individual sewerage system of any kind without first having obtained a permit from the state health officer.”
  Louisiana Administrative Code Title 51, Part XIII, Public Health—Sanitary Code ↗Re-checked Sep 9, 2026
Septic permitRequired
Installation, alteration, or operation of any individual sewerage system in Louisiana, including septic tank systems.
- A permit from the state health officer is required before installation, alteration, or operation.
- Plans and specifications must be approved as part of the permit.
- A temporary installation permit may issue only after the state health officer determines connection to a community-type sewerage system is not feasible and the soil, drainage, lot size/dimensions, and related factors are unlikely to create a nuisance or public health hazard.
- Permits for lots in formal subdivisions require an official recorded plat/property survey filed with and approved by the Office of Public Health for individual sewerage use.
permit stages: two-stage process
“A person shall not install, cause to be installed, alter subsequent to installation, or operate an individual sewerage system of any kind without first having obtained a permit from the state health officer.”
Louisiana Administrative Code Title 51, Part XIII, Public Health—Sanitary Code ↗Re-checked Sep 9, 2026
Septic inspectionLimited
Final approval of individual sewerage system installations in Louisiana.
- Final approval requires verification that the system was installed in compliance with the code.
- Verification may be by an on-site inspection by a representative of the state health officer and/or a completed Certification by Installer from the licensed installer.
- The installer must notify the appropriate local Parish Health Unit before installation.
- The certification must be submitted within 15 days after completion.
certification submission deadline: 15 days after completion
“A final permit approving the installation, shall be issued only upon verification that the individual sewerage system has been installed in compliance with this code. The verification of such installation shall be determined by means of an on-site inspection conducted by a representative of the state health officer and/or in the form of a completed "Certification by Installer" form submitted to the state health officer by the licensed installer.”
Louisiana Administrative Code Title 51, Part XIII, Public Health—Sanitary Code ↗Re-checked Sep 9, 2026
Off-grid sanitationLimited
Use of individual or alternative onsite sewage systems instead of a community-type sewerage system in Louisiana.
- Individual sanitation is allowed only when community-type sewerage is unavailable or connection is not feasible.
- The system requires state-health-officer permitting and approved plans.
- A conventional septic tank system may be used where community sewer is unavailable; an individual mechanical plant may be used only where community sewer is unavailable and the state health officer determines a conventional system would not function properly.
- Innovative systems are limited to no more than three experimental or developmental installations statewide and require specifically approved plans, specifications, testing procedures, and a prior permit.
experimental/developmental installations: <= 3 statewide maximum
“The total number of such installations shall not exceed three throughout the state and shall be approved under the following conditions.”
Louisiana Administrative Code Title 51, Part XIII, Public Health—Sanitary Code ↗Re-checked Sep 9, 2026
Well permitLimited
New water wells statewide in Louisiana, including wells outside critical groundwater areas, except the types specifically subject to post-installation notification or other exemptions.
- All new water wells must be installed by a licensed water-well drilling contractor and registered through the Department of Transportation and Development within 30 days after completion.
- Unless specifically listed in the exemptions, the owner must submit a water well notification form to the commissioner at least 60 days before installation.
- Before construction begins, the drilling contractor must confirm that the Office of Conservation has received and responded to the installation notification.
- Domestic wells, replacement wells, drilling rig supply wells, drought relief wells, and other wells exempted for just cause are subject to post-installation notification rules rather than the ordinary 60-day prior notification.
- The commissioner reviews prior notifications within 30 days and may impose restrictions, request further information, or take no action; an additional 30-day review period may apply if further information is requested.
- For large-volume wells or wells in a critical area of groundwater concern, the commissioner may fix allowable production, spacing, and metering; for other wells outside a critical area, an order may only fix spacing.
- After written confirmation that no restrictions or further information are required, or when the owner accepts imposed restrictions, the owner need not wait the full 60 days and may begin drilling consistently with the notification and restrictions.
prior notification period: 60 days (Does not apply to well types listed in LAC 43:VI §701.C and D.) · registration deadline after completion: 30 days (The applicable state registration requirement applies to all new water wells.) · additional review period if information requested: 30 days (Additional period begins when the requested information is received.)
“require a water well notification form be submitted to the commissioner by the owner of the well at least 60 days prior to installation.”
Louisiana Administrative Code, Title 43, Part VI, §701 ↗Re-checked Sep 26, 2026
One more reviewed finding on this topic
- Limited — Domestic (exempt) water wells statewide; no pre-drilling permit is described, only after-completion notification to the state
  “exempt water wells require a notification to the department of energy and natural resources no later than 60 days after the completion of the water well.”
  GWR: Prospective Well Owners FAQ (DENR archive site, Office of Conservation) ↗Re-checked Nov 6, 2026
Mandatory utility hookupSewer (with conditions)
Residential or other individual sewerage-system sites governed by Louisiana Title 51 Part XIII.
- A temporary individual-system permit may not issue until connection to a community-type sewerage system is determined not feasible.
- A septic tank system may be used only where a community-type sewerage system is not available and the applicable code requirements are met.
“Where a community-type sewerage system is not available, a septic tank system may be used provided that the requirements of §§511.B, 701, 703.A, and 705 are complied with.”
Louisiana Administrative Code Title 51, Part XIII, Public Health—Sanitary Code ↗Re-checked Sep 9, 2026
Agricultural exemptionConditional
Agricultural-purpose subdivision regulation by parish planning commissions in Louisiana.
- The statutory exclusion applies to parish planning regulations governing subdivision of land in unincorporated territory for purposes other than agricultural.
- Municipal planning commissions are separately authorized to regulate subdivision within their jurisdictions; this claim does not establish a municipal agricultural exemption.
- Other statutory rules may still apply, including utility, drainage, sewerage-disposal, and street-planning requirements for qualifying subdivisions under R.S. 33:106.1.
“Before exercising the powers referred to in R.S. 33:110, a parish planning commission shall adopt regulations governing the subdivision of land within unincorporated territory within its jurisdiction for purposes other than agricultural.”
RS 33:112. Subdivision regulations ↗Re-checked Sep 26, 2026
One more reviewed finding on this topic
- Conditional — Agricultural construction licensing exemption applicable in St. Mary Parish.
  “Any farmer doing construction for agricultural purposes on leased or owned land.”
  R.S. 37:2157 — Exemptions ↗Re-checked Sep 30, 2026
Driveway accessRequired
Access connections or driveways connecting property to a Louisiana state highway and involving work in LaDOTD right-of-way.
- The requirement applies to state-highway access connections; access to non-state local roads may instead be governed by the local government.
- The permit certificate must be signed and numbered before construction begins.
- Additional design, drainage, traffic-study, inspection, bonding, and restoration conditions may apply.
“Only upon possession of a signed and numbered Access Connection Permit Certificate may the applicant begin construction of an access connection.”
LaDOTD Access Connections Policy ↗Re-checked Sep 9, 2026
Building in a floodplainLimited
Proposed development in a regulatory floodway in Louisiana communities using the State of Louisiana no-rise certification guidance.
- A no-rise certification with supporting technical data may be submitted when modeling shows 0.00 feet rise.
- If the project causes a rise, it must be modified, compensated for, or proceed through a floodway revision.
- Floodway revision requests must come from the community and be obtained before permit issuance and development.
- The community official must review and approve the supporting data and engineering certification before issuing a permit.
permitted modeled rise for no-rise certification: 0 feet
“Requests for floodway revisions must come from the community and be obtained prior to the issuance of a permit and proceeding with the development.”
State of Louisiana No Rise Certification Guidance ↗Re-checked Sep 9, 2026
Permit feesPublished (with conditions)
State Fire Marshal plan-review or document fees for projects whose plans and specifications are submitted to the Louisiana Office of State Fire Marshal, Code Enforcement and Building Safety.
- A $5 postage and handling fee applies in addition to the plan-review or document fee.
- Fees vary by occupancy classification, project area, number of sprinkler heads or other devices, appeal type, and review type.
- The statute provides a first-submission exemption from all other charges for state and local political subdivisions; subsequent submissions require the fees.
- Performance-based reviews cost twice the applicable review fee plus an additional $100, with a stated $50 resubmission amount for smoke-control and timed-egress reviews.
postage and handling fee: 5 USD (Does not apply to exemption requests and facsimile transmissions.) · assembly occupancy plan review fee for area 0-2500 square feet: 30 USD · educational occupancy plan review fee for area 0-5000 square feet: 30 USD · hotels, dormitories, apartments, lodgings, rooming houses, and residential or board care facilities plan review fee for area 0-2500 square feet: 30 USD · mercantile/business plan review fee for area 0-3000 square feet: 30 USD · industrial, storage, and special structures plan review fee for area 0-10000 square feet: 30 USD
“In addition to a postage and handling fee of five dollars, the owner of the project who submits the plans and specifications shall pay to the office of state fire marshal, code enforcement and building safety a plan review or document fee based on the following schedule:”
Louisiana Revised Statutes §40:1574.1, Costs of handling plans ↗Re-checked Sep 26, 2026
One more reviewed finding on this topic
- Published (with conditions) — State-level fee collected by the Louisiana Uniform Construction Code Commission on permits issued by local government authorities
  “under luccc resolution 2026-01 adopted on july 7, 2026, the commission has set the fee amount to ten dollars per permit.”
  Ten dollar fee per permit - clarification on applicable permits (LUCCC, released Sept. 8, 2026) ↗Re-checked Nov 6, 2026
Campground & park staysProhibited
Overnight camping on Louisiana public property that is not a designated campground.
- The prohibition applies to public property owned or controlled by the state or any local or political subdivision.
- Designated campgrounds are excluded from the prohibition.
- Violation may result in a fine of not more than $500, imprisonment for not more than six months, or both.
- The statute states an effective date of June 9, 2026.
maximum fine: <= 500 USD · maximum imprisonment: <= 6 months
“Unauthorized camping on public property is the intentional use of any tent [...] to permit overnight use on public property that is not a designated campground.”
RS 14:107.6. Unauthorized camping on public property ↗Re-checked Sep 26, 2026
One more reviewed finding on this topic
- Limited — Temporary stays at facilities operated or reserved through the Louisiana Office of State Parks.
  “Reservations are required in advance of a visit to a park area if a visitor expects the Office of State Parks to hold a facility for their use. If a facility is not reserved, it can be rented at any time, for up to 14 consecutive nights or 15 consecutive days.”
  Louisiana Office of State Parks Policy and Procedure Memorandum #6 — Reservation Changes and Refunds ↗Re-checked Sep 9, 2026
county zoning authorityLimited
Louisiana parish governing authorities' zoning authority over parish land, including unincorporated areas, under the statewide parish zoning enabling subpart.
- The general parish zoning authorization excludes Rapides, Jefferson, Sabine, and Webster Parishes.
- A parish may divide the parish into zoning districts, and regulations may differ between districts but must be uniform for each class or kind of land and structure within each district.
- Zoning regulations must comply with the required comprehensive plan.
- No regulation becomes effective until after a public hearing.
- Notice must be published once a week in three different weeks in the official parish journal, with at least fifteen days between first publication and hearing.
- At least ten days before the hearing, the parish must make a good-faith attempt to notify owners of record by certified mail; when more than ten parcels are zoned or rezoned, official-journal advertisement is adequate notice.
- To use the powers of the subpart, the parish governing authority must appoint a zoning commission, which must hold a public hearing and issue its final report before the governing authority holds its public hearings or acts.
excluded parishes: Rapides, Jefferson, Sabine, and Webster · publication interval: 3 different weeks · minimum elapsed time before hearing: >= 15 days · owner notice deadline: >= 10 days before hearing (Good-faith certified-mail notice; official-journal advertisement is adequate when more than ten parcels are zoned or rezoned.)
“For the purpose of promoting the health, safety, morals, or general welfare of the community, the governing authorities of parishes, other than the parishes of Rapides, Jefferson, Sabine, and Webster, or their duly created boards of adjustment are hereby authorized to regulate and restrict the height, number of stories, and size of structures; the percentage of lots that may be occupied; courts and other open spaces; the density of population; and the location and use of the buildings, structures, and land for trade, industry, residence, or other purposes.”
RS 33:4780.40 — Regulation authorized ↗Re-checked Sep 26, 2026
One more reviewed finding on this topic
- Limited — Louisiana parish governing authorities adopting zoning regulations affecting parish territory, including unincorporated areas.
  “the governing authorities of parishes, other than the parishes of Rapides, Jefferson, Sabine, and Webster, or their duly created boards of adjustment are hereby authorized”
  La. R.S. 33:4780.40 — Regulation authorized ↗Re-checked Sep 21, 2026
county building authorityGeneral
Louisiana parishes may enforce the statewide construction codes and administer building-code enforcement, including permits and inspections, in unincorporated areas.
- Parishes must enforce only the construction codes provided in the Louisiana State Uniform Construction Code Part.
- Enforcement includes plan review, inspections, and issuance, denial, or revocation of permits.
- Each parish must appoint a council-certified building official or contract for those services so the unincorporated area is under the jurisdiction of a certified building official.
- A parish may use a certified building inspector instead of a certified building official for no more than four years from the date the state uniform construction code becomes effective in the parish.
- The statute preserves federal manufactured-housing requirements and Louisiana Manufactured Housing Commission jurisdiction for manufactured-home construction, installation, service, renovation, repair, and warranty work.
- The statute page identifies an amendment effective July 1, 2026.
temporary certified-inspector period: <= 4 years (Measured from the date the state uniform construction code becomes effective in the parish or municipality.)
“all municipalities and parishes in this state shall enforce only the construction codes provided for in this Part.”
RS 40:1730.23. Enforcement of building codes by municipalities and parishes ↗Re-checked Sep 26, 2026
One more reviewed finding on this topic
- General — Louisiana parishes' authority and duty to enforce the state construction codes, including residential construction codes, through building-code enforcement officers or certified third-party providers.
  “Notwithstanding any other law to the contrary relating to the authority of local governments to enforce construction codes, all municipalities and parishes in this state shall enforce only the construction codes provided for in this Part. All municipalities and parishes shall use building code enforcement officers or certified third-party providers contracted by the municipality, parish, or regional planning commission to act in the capacity of a building code enforcement officer to enforce the provisions of this Part.”
  RS 40:1730.23 — Enforcement of building codes by municipalities, parishes, and the fire marshal ↗Re-checked Sep 26, 2026

Still unanswered

We looked and could not find an official answer yet. Silence is not permission — ask the county directly.

Living in an RV — Long-term occupancy of a recreational vehicle on private land in unincorporated St. Mary Parish.
Camping on your land — Temporary camping on private land in unincorporated St. Mary Parish.
Tiny homes — Occupancy of a tiny home in unincorporated St. Mary Parish.
Accessory dwellings — Accessory dwelling units in unincorporated St. Mary Parish.
Short-term rentals — Short-term rental use in unincorporated St. Mary Parish.

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.

Living off-grid in St. Mary Parish, Louisiana

Is St. Mary Parish a good place to live off-grid or homestead?

St. Mary Parish scores 63/100 on the Bolthole Index, a solid county profile. Its strengths: manageable long-term carry cost and about 36,463 people within 15 miles.

How much does land cost in St. Mary Parish, Louisiana?

Land in St. Mary Parish runs about $3,498 per acre, based on the latest county data.

What is the water situation in St. Mary Parish?

St. Mary Parish gets about 60.7" of rain a year, with severe drought in roughly 8.9% of years.

How remote is St. Mary Parish?

A typical private-land location has about 36,463 people within 15 miles and 3,156,216 within 100 miles. These radius catchments are the published fallback where road routing is unavailable.

Building permits, zoning and land rules in St. Mary Parish, Louisiana