Single Family Major Renovation

A Major Renovation is more extensive than a Single Family Addition. When the amount of added habitable floor area (excluding basement area) exceeds 115 percent of the habitable floor area (excluding basement area) of the existing dwelling, a Major Renovation permit will be required. Calculations documenting existing and new areas must be provided on the cover sheet of the permit drawings to confirm the status of the proposed project. A Major Renovation will require the installation of a new 13D residential sprinkler system for the entire residence.

Example: A second story addition is proposed for an existing single story residence with basement and attached garage.  The area of the second story will be contained within the footprint of the first floor which also contains the area of the garage.

Existing Gross Area of the first floor: 25' x 70' = 1750 sf
Proposed Gross Area of the second floor addition: 25' x 70' = 1750 sf

To determine the threshold for a Major Renovation:

Subtract the net area of the garage (not habitable space): 1750 sf - 400 sf = 1350 sf
Find 115 percent of the resulting first floor area: 1350 sf x 1.15 = 1552.5 sf

Conclusion: 1750 sf > 1552.5 sf, therefore the project qualifies as a Major Renovation

Habitable floor area for use in the above calculations will not include attached garages or attached unconditioned sunrooms.

Application Requirements

  • Permit Application Packet- Documents below have been combined into this one PDF file.
    1. Building Permit Application
    2. Zoning Worksheet – Residential
    3. Building Site and Utility Data Worksheet
    4. Water Service and Meter Worksheet
    5. Whole House Mechanical Ventilation System Worksheet
    6. Fire Protection – Letter of Understanding (separate Fire Protection permit required)
    7. Contractor of Record (Contractor License Requirements / Contractor License Application)

Application Fees & Deposits

  • Building Construction and Inspection Fee - $1.80 per square foot of addition floor area and $1.50 per square foot of interior alteration, if applicable (Fees due at time of permit pick-up)
  • Permit Application Deposit - $250 (Due at time of permit application submission)
  • Additional fees may apply at time of permit pick-up

Drawing Requirements (To Be Submitted With Permit Application)

Please review the Residential Plan Review Checklist prior to submitting your drawings and read through the Common Residential Plan Submission Mistakes.

*The Village of Northbrook Standard Detail Sheet should be included within the civil engineering drawing set.

Separate Permit Requirements

The following may occur with the construction of a new single family residence and require a separate permit:

Construction Submittal Requirements

The following may apply during the course of construction:

Required Inspections

Additional Resources