Accessory Structure - Residential

  • Adopted Building Code: 2012 International Residential Code (IRC)
  • Adopted Mechanical Code: 2012 International Mechanical Code
  • Adopted Electrical Code: Current National Electrical Code (NEC)
  • Adopted Plumbing Code: Current Illinois Plumbing Code
  • Adopted National Fire Protection Association (NFPA) Code: 101 Life Safety Code, 2006 Edition
    (Copies are available at City Hall for viewing)

What to Bring

  1. Site Plan (a dimensioned drawing showing property boundary dimensions, existing and proposed buildings and improvements, dimensions of all buildings, and distances or setbacks from buildings to property lines). Example.
  2. Name, address, and phone number of property owner and contractor. Be sure you are aware of any easements, including utilities, that may be on your property. JULIE may be contacted at 811 if you are in need of assistance.
  3. Completed Accessory Building Permit Application.

Building permits for this type of construction are generally issued while you wait.

What Fees to Expect

Building Permit Fee:

$40 filing fee plus $2 for every $1,000 in estimated construction value for each accessory structure permit that requires up to two (2) inspections. $65 filing fee plus $2 for every $1,000 in estimated construction vale for each accessory structure permit that requires three (3) inspections. If construction commences without a valid building permit, the above fee shall be doubled. Only property owners or an authorized agent can sign the permit application.

Zoning Setback and Size Requirements - Accessory Structure Residential

Size Requirements:

The aggregate ground floor area of all accessory structures on any single lot up to ½ acre in size shall not exceed the lessor of: 1) 1,200 square feet; or 2) the ground floor area of the principal structure on the property. The aggregate ground floor area of all accessory structures on any single lot greater than ½ acre in size shall not exceed the following limitations: 1) lot size up to 1 acre = 1,600 square feet; 2) lot size larger than 1 acre up to 2 acres = 2,000 square feet; and 3) lot size larger than 2 acres = no limit. Note on Total Lot Coverage: Total lot coverage for all structures (includes the principal structure) on the property cannot exceed 40% in the R-1 zoning district and 60% in the R-2 zoning district.

Setback Requirements:

Zoning District

Side Yard

(taken from overhang)

Rear Yard

(taken from overhang)

Distance Between Structures

(taken from building wall)

R-1 (1 & 2 family)

R-2 (2 & Multifamily)







It is the owner's responsibility to notify the City during normal business hours, at least one (1) business day (twenty-four hours) in advance of the following phases of construction:


  • Prior to pouring concrete or setting block for the foundation and prior to backfill. Principal items to be inspected include the setbacks, footing and foundation widths and depths, reinforcing steel, and foundation drainage.
  • Prior to covering over the framing and roughed-in electrical and plumbing. Principal items to be inspected include the frame, floor joists, firestopping, roof trusses, and roughed-in electrical wiring (minimum 12 gage per City Ordinance), circuits and grounding, and roughed-in plumbing. This inspection is done prior to exterior siding installation.
  • Upon completion of the building or structure and before the issuance of the Certificate of Occupancy. Principal items to be inspected include a final check of the structure, interior and exterior walls, roof, operability of fixtures and equipment, final electrical inspection of conductors, lighting and receptacles, circuits, water meter installation, and final plumbing inspection.

Inspection Requirements Based on Type of Construction

Room Addition All Three Phases Mentioned Above

Storage sheds under 600 sq. feet

Storage sheds 600 sq. feet and over



Swimming Pools


No Footing Required - Final Inspection Only

Footing Required - Footing & Final Inspection only

Footing & Final Inspection - Framing only if Interior Walls are Covered

Footing & Final Inspection Only

Bonding & Final Inspection

No Inspection Required

Copies are available for review at City Hall. Inspections focus only upon the work which is the subject of the Building Permit. Inspectors will review the building to determine compliance with the 2012 International Residential Code.

Contact Us

City Hall
301 Walnut St
Washington, IL 61571
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301 Walnut St, Washington IL 61571
  • (309) 444-3196
  • (309) 444-9779
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