Illinois
Lot Split and Minor Subdivision
Split one parcel into two or a few lots, with the survey, plat and engineering your county needs to approve it.
What the work involves
A lot split or minor subdivision divides a parcel into a small number of lots without new streets. The land surveyor prepares the plat or survey, and an engineer may be needed to show each lot has access, drainage and a sewer connection or septic area that passes soil testing. Requirements vary widely, and some jurisdictions handle these administratively.
Local conditions we plan for
- Frost depth and freeze thaw damage
- Riverine flooding (Mississippi, Illinois rivers)
- Soft lake clays and deep foundations in Chicago
- New Madrid Seismic Zone exposure in southern Illinois
Building code: No statewide IBC/IRC; codes adopted by local jurisdictions (ICC adoption chart, April 2026).
When you need it
- Splitting a large lot to sell or build a second house
- Creating a lot for a family member
- Adjusting a lot line between neighbors
- Each new lot needs septic approval or sewer
- Lots need new driveway access
Frequently asked questions
How much does lot Split and Minor Subdivision cost?
Across the US, lot Split and Minor Subdivision usually costs $2,000 to $15,000. Estimate. Survey and plat costs (HomeGuide and Fixr ranges) plus perc testing and any engineering. Sites that need sewer extensions or road improvements cost more.
How long does lot Split and Minor Subdivision take?
Plan on 1 to 6 months from signed proposal to stamped deliverables, longer if a site visit, soil testing or a permit review cycle is involved.
Do I need a licensed PE for lot Split and Minor Subdivision?
In most US jurisdictions, yes. When the work needs a permit, the plans, calculations or report usually must be sealed by a Professional Engineer licensed in the state where the project is located. Every deliverable we issue for permit is sealed that way.
How do I verify an engineer's license in Illinois?
Engineers practicing in Illinois are licensed by the Illinois Department of Financial and Professional Regulation (IDFPR), Professional Engineering Board. You can confirm a license number and its status in the board's public license search before you sign a contract.
Which building code applies in Illinois?
No statewide IBC/IRC; codes adopted by local jurisdictions (ICC adoption chart, April 2026). Cities and counties can add local amendments, which is one reason to hire an engineer who works in your area.
What site problems do engineers see most in Illinois?
Common issues include frost depth and freeze thaw damage, riverine flooding (Mississippi, Illinois rivers), soft lake clays and deep foundations in Chicago and new Madrid Seismic Zone exposure in southern Illinois.