Washington

ADU Pass helps homeowners in Washington, St. Landry Parish, Louisiana navigate the permit paperwork for building an accessory dwelling unit. This area covers 1 ZIP code.

1 ZIP code

ADU details

ADU legality: unclear

Stateunclear (Louisiana accessory-dwelling framework) — Louisiana statewide ADU posture per state-adu-research file.
Countywith-restrictions (St Landry Parish unincorporated zoning) — St Landry Parish permits ADUs in unincorporated areas under state-law-aligned standards. Within Washington city limits the city ordinance plus state law govern.
Citywith-restrictions (City of Washington Municipal / Zoning Code — Accessory Dwelling Units) — City of Washington permits ADUs under the local ordinance aligned with Louisiana statewide framework where applicable.

Louisiana leaves ADU regulation to local municipalities under home-rule or Dillon-rule authority. Washington permits ADUs subject to local conditions per its zoning ordinance.

Cost scenarios

ScenarioSq ft PermitBuildTotal
minimum 150 $1,800 $34,500 $36,300
600 600 $1,800 $138,000 $139,800
midpoint 525 $1,800 $120,750 $122,550
maximum 900 $1,800 $207,000 $208,800
Fee breakdown
Plan review$540
Building permit$990
Impact fees$270
Total$1,800

Viability (permitted uses)

  • Long-term rental: yes Long-term rental of ADU generally permitted; landlord-tenant law and any city rental-registration ordinance apply.
  • Short-term rental: with-restrictions STR rules vary by city. Washington regulates STRs separately from ADU permitting; check local STR ordinance and HOA covenants.
  • Office rental: with-restrictions Detached office rental requires home occupation permit or rezoning.
  • Home office: yes Home occupation permitted with restrictions on signage and customer traffic.
  • Studio / workshop: yes Personal artist studio is a permitted accessory use.
  • Agriculture: with-restrictions Limited urban agriculture permitted in residential zones; livestock varies by district.
  • Relative support: yes Family-occupancy ADU explicitly permitted in single-family zones.

Utilities

  • Water: Washington Water Utility · 30d connect · $4,500
  • Sewer: Washington Sewer / Wastewater · 30d connect · $5,500
  • Electric: Washington Electric Utility · 21d connect · $1,800
  • Gas: Washington Gas Utility · 30d connect · $1,500

Property values & taxes

Median value$350,000
Median tax$3,500/yr
Effective rate1%

Construction timeline

Detached build24 weeks
Conversion14 weeks
Contractor lead3 months

Realistic total: best 7mo · typical 10mo · worst 16mo

Financing

Insurance impact

Annual premium delta$720
Landlord policyrecommended
Umbrella threshold$1M umbrella when renting

HOA prevalence & preemption

State HOA preemptionno

Louisiana has no HOA-ADU preemption; HOA covenants restricting ADUs are enforceable.

Technical envelope (climate & building code)

Climate & energy code

IECC climate zone2A
Heating degree days1,600
Cooling degree days2,700
Design low / high30°F / 93°F
Wind design speed150 mph
Seismic design cat.B
Annual rainfall67"
Wildfire exposurelow
Energy codeIECC
Version / adopted2015 / 2017

Building code

Base codeIRC
Version year2,015
Adopted2017
Fire sprinklernone
Egress window5.7 sqft min
Min ceiling7 ft
Attic R-valueR-38 min
Wall R-valueR-13 min

Amendments:

  • Amendment
  • Amendment
Louisiana state — ADU law and programs

State financing programs

Louisiana does not operate an ADU-specific statewide loan, grant, or forgivable-loan program. The Louisiana Housing Corporation (LHC) is the state housing finance agency and administers down-payment-assistance programs (Mortgage Revenue Bond Assisted, MRB Home, MRB Home Assisted), the LHC Preferred Conventional Program, the HOME Program (for development), the Rental Restoration and Development Program (RRDP), Weatherization Assistance, and HUD-funded affordable housing development. None target ADU construction directly. ADU costs may be financed through standard renovation or construction-loan products under LHC programs when the ADU is part of a qualifying primary-residence transaction.

Federal (United States) — ADU-relevant rules and programs

Federal ADU law

The United States has no federal statute that directly regulates accessory dwelling unit entitlement or design. Land-use authority over ADUs resides with states and local governments under the traditional police power. Federal engagement is limited to financing (Fannie/Freddie/FHA/VA/USDA), flood insurance (FEMA/NFIP), and discretionary housing programs (HUD), which are recorded in sibling sections of this file.

Federal financing programs

Federal housing-finance agencies and GSEs set nationwide underwriting rules that govern whether an ADU can be financed, appraised, and counted toward mortgage qualifying income. The relevant actors are Fannie Mae, Freddie Mac, FHA (HUD), VA, and USDA Rural Development.

Federal tax credits

There is no ADU-specific federal tax credit. ADUs may incidentally qualify for existing federal energy-efficiency and clean-energy tax credits when the ADU construction includes qualifying measures.

Federal housing programs

HUD administers several discretionary programs that can fund ADU-related activity at the grantee's election, but none is an ADU-specific program.

ZIP Code

  • 70589

Post Office

  • 112 E Moundville St, 70589