ADU, Subdivision & Development in Jefferson County
Have land you want to subdivide? Exploring an ADU or development project? Get local guidance for Jefferson County.
Jefferson County Planning Resources
Jefferson County Planning & Zoning
Subdivisions, zoning, variances
729 Maple St, Hillsboro, MO 63050
(636) 797-5321
Visit Website →Land Development in Jefferson County
Septic Requirements Drive Lot Sizes
Much of Jefferson County relies on septic systems. Soil conditions and septic requirements often determine minimum lot sizes and subdivision feasibility. Get a perc test early in your planning process.
Land Subdivision
Jefferson County has many larger parcels with subdivision potential. Check zoning, septic feasibility, and road access.
ADU/Secondary Structure
Larger rural lots may accommodate ADUs. Septic capacity is key consideration.
Agricultural/Rural
Farm and agricultural uses have different requirements. Contact Planning for ag exemptions.
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Jefferson County Development FAQs
Can I subdivide my land in Jefferson County?
Jefferson County allows subdivision with proper approvals. Contact Planning & Zoning at (636) 797-5321. Requirements include minimum lot sizes (vary by zoning), road frontage, and utility/septic access. Rural areas with septic have larger minimum lot requirements. Process takes 3-12 months.
What are the minimum lot sizes in Jefferson County?
Lot sizes vary by zoning district. Agricultural zones may require 3+ acres. Residential zones vary from 10,000 sq ft to several acres. Properties requiring septic systems typically need larger lots (often 1+ acre). Check your zoning classification with Planning & Zoning or on the County GIS.
Can I build an ADU on my Jefferson County property?
ADU rules in Jefferson County depend on your zoning district and lot size. Many rural properties can accommodate secondary structures. Contact Planning & Zoning for requirements including setbacks, size limits, and whether the ADU can be used as a rental. Septic capacity must support additional occupancy.
What about septic requirements for new lots?
New lots in Jefferson County without sewer access need septic approval from the Health Department. A perc test determines if soil can support a septic system. Some areas have soil limitations. Septic requirements often drive minimum lot size. Get soil tested before finalizing subdivision plans.
Should I subdivide my land myself or sell to a developer?
Subdividing yourself can maximize profit on larger parcels but requires 6-12+ months, survey and engineering costs, and navigating approvals. Selling to a developer is faster and shifts risk. For land with significant subdivision potential, consider getting preliminary feasibility before selling.
Documents for Jefferson County Development Projects
Having these items ready helps us give you accurate guidance faster:
- Property deed
- Current survey/plat
- Zoning classification
- Perc test results (if applicable)
- Title report
- Utility locations/availability
- Road access documentation
- Property tax records
Don’t have everything? That’s okay – start with what you have.
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Important: This information is educational and specific to Jefferson County, Missouri. Always verify requirements with Planning & Zoning and the Health Department for septic.