Bolthole Index

Lake County, Illinois

Building permits, zoning and septic rules in Lake Forest, Illinois

Lake Forest, Illinois requires a building permit from the city's Community Development office for any construction, alteration, repair or removal of a building1. The city also runs its own zoning under Chapter 159 of its code2. Septic permits and well permits are not decided by the city: in Lake County, the Lake County Health Department handles septic systems on properties without public sewer3.

At a glance

Building permit
Required from the City of Lake Forest1
Zoning
City zoning (Chapter 159) with many districts24
Inspections
Required at each construction phase5
Certificate of occupancy
Required before occupying a new or converted building6
R-1 minimum lot
9,375 sq. ft. and 75 ft wide for a single-family house7
Septic
Lake County Health Department, where there is no public sewer3
Wells
Permit required from the Lake County Water Well Program8

Who to call

Building permits

City of Lake Forest Community Development

Building permits, inspections and zoning questions inside Lake Forest city limits (phone is City Hall's main line)

(847) 234-2600

220 East Deerpath, Lake Forest, IL 60045

Septic permits

Lake County Health Department — Onsite Wastewater Treatment System

Septic system review, approval and construction inspections on properties without public sewer; also water well permits

847-377-8020

[email protected]

500 West Winchester Road, Libertyville, IL 60048

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 Lake Forest means bringing your own water and power. The kit we’d start with:

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Does Lake Forest, Illinois have zoning, and what does it mean for lots and setbacks?

Yes. The City of Lake Forest adopts and administers its own zoning ordinance, Chapter 159 of its code, with residence, office and business districts2. Residence districts include R-1 through R-5, the GR general residence districts, OA Open Area and ROS Residential Open Space4.

Rules change by district, so check the parcel's district first. In the R-1 single-family district, a detached house needs a lot of at least 9,375 sq. ft. and 75 ft wide7. Required yards for an R-1 single-family house are 40 ft front, 10 ft interior side, 40 ft corner side and 35 ft rear9.

We could not confirm what the city's zoning allows for RVs, tiny homes, manufactured homes or temporary camping on a residential lot. Ask the Community Development office before you plan on any of them.

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

Yes. Inside Lake Forest, the contractor must obtain a permit from the office of the director of community development before excavating for or constructing, altering, repairing or removing any building or structure1. The city's Community Development page says most home improvement projects require a permit before work begins10.

A permit is not issued unless the premises comply with the zoning ordinance1. New construction and additions also require a cash bond of at least $5001. The city adopts specific codes by reference, including the Illinois Plumbing Code11; we did not confirm the edition years of its general building code. Illinois itself does not issue building permits for private construction; the city or county does12.

The county's building permit rules cover only unincorporated land. For land outside city limits, see the Lake County page.

How do septic permits work inside Lake Forest?

We could not confirm whether any addresses inside Lake Forest rely on septic systems or how the city treats them. Where a property is not served by public sewer anywhere in Lake County, the Lake County Health Department regulates septic treatment and dispersal313. A septic construction permit is applied for by a licensed septic contractor and is valid for 120 days14. Illinois requires plan approval from the Illinois Department of Public Health or the local health authority before a new private sewage system is built15.

We also could not confirm whether the city requires connection to public water or sewer. Ask Community Development before assuming either way.

Building a home in Lake Forest: the steps, in order

  1. Confirm the parcel's zoning district and its lot-size and yard rules with the city4.
  2. Ask the city whether public sewer and water serve the lot; if not, contact the Lake County Health Department about septic and well permits8.
  3. Apply for a building permit from the director of community development, with architectural and plot plans drawn to at least one-eighth inch to the foot16.
  4. Post the cash bond for new construction1.
  5. Request approval of each construction phase before moving to the next5.
  6. Obtain a certificate of occupancy before anyone occupies the building6.

What stays with Lake County, and what to check before you buy

Water wells in both incorporated and unincorporated Lake County need a permit from the county's Water Well Program8. Septic systems answer to the Lake County Health Department wherever there is no public sewer17. Projects on properties with a septic system or well, driveways included, must be reviewed by the Health Department18.

Flood and drainage: Lake County's watershed development permitting applies to major and minor development in the county19.

Costs are county-level: Lake County's effective property tax rate is 2.7%20 and the median property tax bill is $8,743 a year21. The typical home value is $400,96422.

Watch-outs

  • Lake County's building and zoning offices serve only unincorporated land, so do not take a Lake Forest project to the county permit counter23.
  • We could not confirm Lake Forest's rules on owner-builders, RVs, tiny homes and sewer connection; ask the Community Development office, and take septic and well questions to the Lake County Health Department178.

Sources

  1. § 150.145 Permits and Fees, City of Lake Forest Code of Ordinances (Lake Forest), quoted and re-checked
  2. Chapter 159: Zoning, City of Lake Forest Code of Ordinances (Lake Forest), quoted and re-checked
  3. Onsite Wastewater Treatment System, quoted and re-checked
  4. Chapter 159: Zoning, City of Lake Forest Code of Ordinances (Lake Forest), quoted and re-checked
  5. § 150.143 Certificate of Occupancy (and § 150.142 Inspections), City of Lake Forest Code of Ordinances (Lake Forest), quoted and re-checked
  6. § 150.143 Certificate of Occupancy (and § 150.142 Inspections), City of Lake Forest Code of Ordinances (Lake Forest), quoted and re-checked
  7. § 159.085 R-1 Single-Family Residence District, City of Lake Forest Code of Ordinances (Lake Forest), quoted and re-checked
  8. Environmental Health Permit Applications and Forms, quoted and re-checked
  9. § 159.085 R-1 Single-Family Residence District, City of Lake Forest Code of Ordinances (Lake Forest), quoted and re-checked
  10. City of Lake Forest Community Development (cityoflakeforest.com)
  11. Chapter 150: Buildings, City of Lake Forest Code of Ordinances (Lake Forest), quoted and re-checked
  12. Illinois Codes FAQ (Illinois statewide rule), quoted and re-checked
  13. Lake County Health Department — Onsite Wastewater Treatment System (lakecountyil.gov)
  14. Onsite Wastewater Treatment Systems, quoted and re-checked
  15. 77 Ill. Adm. Code 905.190 Installation Approval (Illinois statewide rule), quoted and re-checked
  16. § 150.145 Permits and Fees, City of Lake Forest Code of Ordinances (Lake Forest), quoted and re-checked
  17. Onsite Wastewater Treatment System, quoted and re-checked
  18. Environmental Health Permit Applications and Forms, quoted and re-checked
  19. Permits & Approvals, quoted and re-checked
  20. Effective property tax rate: Bolthole Index county data
  21. Median property tax bill: Bolthole Index county data
  22. Typical home value (Zillow): Bolthole Index county data
  23. Unified Development Ordinance, quoted and re-checked

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 Lake Forest

Lake Forest’s own rules

  • Building permitRequired

    Construction, alteration, repair or removal of any building or structure inside Lake Forest city limits.

    • Permit comes from the office of the director of community development (§ 150.145(a)).
    • Permits are void if work is not started within 90 days or completed within one year of issuance; renewal for one year at 10% of original fee; director may extend 90 days (§ 150.145(b)).
    • A permit is not issued unless the premises complies with the zoning ordinance and other pertinent city ordinances (§ 150.145(e)).
    • Application requires architectural plans and plot plans at a scale of not less than one-eighth inch to the foot, or a written description where the director allows (§ 150.145(c)).
    • Cash bond of not less than $500 required on all new construction and additions (§ 150.145(f)).

    minimum cash bond for new construction and additions: >= 500 USD (amount set from time to time by council resolution, not less than $500) · permit validity: work must start within: 90 days

    “before proceeding with the excavation for or the construction, alteration, repair or removal of any building or structure, the contractor shall request and obtain a permit for such work from the office of the director of community development.”
  • Building code adoptedPartial

    Construction inside Lake Forest city limits under Code of Ordinances Chapter 150 (Buildings).

    • The chapter table of contents shows the city adopts specific codes by reference, including the Illinois Plumbing Code (§ 150.380) and an electrical code (§ 150.295 adoption of electrical code), and a fuel gas code (§ 150.505).
    • The general building code adoption section and the edition years were not opened, so only partial adoption is recorded.
    “150.380 adoption by reference of illinois plumbing code”
  • InspectionsRequired

    Buildings and structures being constructed, repaired, altered, remodeled or razed inside Lake Forest city limits.

    • Contractor must request and receive approval of each phase before proceeding to the next phase of new construction (§ 150.142(b)).
    • Contractor must call for inspections, with a representative on site, including excavation, footing or piers, and foundation, waterproofing and draintile (§ 150.142(c)); the full list is in the same section and was not fully read.
    • Required inspections are set out for each phase of remodeling or repair per the director's written notice (§ 150.142(e)).
    “the director of community development shall inspect or cause to be inspected, all buildings or structures which are being constructed, repaired, altered, remodeled or razed.”
  • Certificate of occupancyRequired

    Occupancy or use of a building or premises created, erected, changed or converted inside Lake Forest city limits.

    • Conditional certificate of occupancy may be issued when the structure is nearly complete and the director finds use will not endanger safety (§ 150.143(b)); the owner must sign an agreement, post a cash bond and correct items within six months (§ 150.143(b)(2)).
    • A certificate of use is required for occupancy of any nonhabitable building or premises (§ 150.143(c)).
    “it shall be unlawful to occupy or use, or permit the occupancy or use of any building or premises or part thereof, hereafter created, erected, changed or converted wholly or partly, until a certificate of occupancy has been issued”
  • Local zoningPresent (with conditions)

    Land inside Lake Forest city limits: the city's own zoning ordinance (Code of Ordinances Chapter 159, Zoning) administers residence, office, business and other districts.

    • Use and dimensional rules differ by district; see the district-specific claims for R-1 and the zoning_districts claim.
    • Checked against the American Legal Publishing copy of the code, current through Ord. 2023-030 per the overview page; not checked against the official printed copy.
    “special uses may be allowed in the r-1 district as provided in § 159.045.”
  • Zoning districtsPublished

    Zoning districts of Lake Forest city (Chapter 159) inside city limits.

    • Residence districts include R-5, R-4, R-3, R-2, R-1, GR-4 to GR-1, OA Open Area and ROS Residential Open Space (§§ 159.080-159.092).
    • Office, business and other districts are listed under §§ 159.105 onward.
    “159.085 r-1 single-family residence district 159.086 gr-4 general residence district”
  • Minimum lot sizeSpecified

    Single-family detached dwelling lots in the R-1 single-family residence district inside Lake Forest city limits (main single-family district).

    • Truck and flower gardens and nurseries in R-1 require 5 acres and 300 ft minimum width (§ 159.085(c)).
    • The lot-size table is a Chapter 159 district requirement, not a countywide rule.

    minimum lot area, single-family detached dwellings, R-1: >= 9375 sq. ft. · minimum lot width, single-family detached dwellings, R-1: >= 75 ft

    “minimum lot area minimum lot width single-family detached dwellings 9,375 sq. ft. 75 ft. truck and flower gardens and nurseries 5 acres 300 ft.”
  • SetbacksSpecified

    Principal single-family detached dwellings in the R-1 single-family residence district inside Lake Forest city limits.

    • Setbacks are given in linear feet (§ 159.085(d)).
    • Accessory buildings in R-1: front yard 40 ft, interior side 5 ft, corner side 30 ft, rear 5 ft (§ 159.085(d)(2)).
    • Parks, playgrounds and municipal buildings have different setbacks (not used here).

    front yard setback, single-family detached dwelling: 40 ft · interior side yard setback, single-family detached dwelling: 10 ft · corner side yard setback, single-family detached dwelling: 40 ft · rear yard setback, single-family detached dwelling: 35 ft

    “single-family detached dwellings 40 10 40 35”
  • Permit processPartial

    Building permit application process inside Lake Forest city limits.

    • Application is on a form furnished by the director of community development's office, with architectural and plot plans at a scale of not less than one-eighth inch to the foot (§ 150.145(c)).
    • A limited building permit may be issued for up to 30 days when plans are sufficient or written assurance of code compliance is given (§ 150.145(d)).
    • The application form and fee schedule were not located online; process is only partially published.
    “application for a building permit shall be submitted on a form furnished by the office of the director of community development.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Lake Forest or Lake County directly.

  • Owner-builder exemption — Owner-builder permitting inside Lake Forest city limits.
  • Minimum dwelling size — Minimum dwelling floor area inside Lake Forest city limits.
  • Lot coverage — Lot coverage by buildings inside Lake Forest city limits.
  • Building height — Building height limits inside Lake Forest city limits.
  • Living in an RV — Occupancy of recreational vehicles on residential land inside Lake Forest city limits.
15 more unanswered
  • 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

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 Lake Forest publishes no rule on the point, not that none exists. Lake County’s page lists the county offices to call.

← All of Lake County: county rules, score and offices