Building Code FAQs

Single & Multi Family

  1.  When and where do I need a smoke detector/carbon monoxide alarm?
    Refer to Smoke Alarms R314  & Carbon Monoxide Alarms R315 in the 2021 International Residential Code (IRC) for information on location requirements.
  2. Do I need a floor or landing at an exterior door?
    Yes, a minimum size is 3' x 3' landing or floor on each side of every exit door and the width should not be smaller than the door. A slope not exceeding 1/4 unit vertical in 12 units horizontal (2%)
  3. Do I need a landing at my interior stairway?
    Yes, at both top and bottom of stairs.
    EXCEPTION: A floor or landing is not mandatory at the top of an interior staircase, including stairs in an enclosed garage as long, as the door does not swing outward over the stair.
  4. What is the minimum footer size in Sussex County?
    Continuous footer: 12"x 6" – no rebar required but recommended.
  5. What is the minimum depth of footers?
    The minimum depth is 24" to the bottom of the footer from final grade.
  6. What is the minimum size for a post hole?
    The minimum size is 3” larger than the post on all sides.
  7. Are Gutters and Downspouts required on a new home, addition, or detached building?
    Yes, new homes, additions, and detached buildings are required to have gutters and downspouts to collect and convey roof water away from the building’s foundation.
    EXCEPTION: Homes on structural pilings or pole style buildings do not need gutters. Also, a certification from a Delaware Engineer based on soil analysis may waive gutter requirements.
  8. Is there a list of code requirements?
    Yes, please refer to our Additional Code Requirements sheet.
  9. What is RES Check?
    A RES Check report is an energy code compliance analysis which documents that your residential building will meet or exceed the energy conservation standards developed by the U.S. Department of Energy Office of Building. The RES Check report includes Certificates of Compliance and Compliance Checklists consistent with the International Energy Conservation Code (IECC).
    For information on Energy Codes visit
    For information on creating a RES Check view Energy Codes' PDF
  10. What is Manual J, and Manual S?
    Manual J is the protocol used for determining the amount of heating and cooling that a home requires to keep its occupants warm in the heating months and cool and dry in the cooling months.
    Manual S is used to size and select the heating and cooling equipment. The goal for equipment selection is to install heating and cooling systems with the same heating and cooling capacities as the heating and cooling loads of your home.
    For a list of approved software programs visit ACCA's website


  1. What wind speed are commercial buildings required to build to in Sussex County?
    Wind speed designs can be from 105 mph to 140 mph, depending on location and the risk category for the use of the proposed structure.
  2. Do I need a Com Check to submit plans for my commercial building?
    Yes, all new construction must be designed and constructed to the International Energy Conservation Code.
  3. What direction do egress doors need to swing?
    Typically exit doors need to swing in the same direction of travel where the serving room or area contains an occupancy load of 50 or more persons.
  4. What is the frostline for commercial buildings?
    24 inches
  5. What is the slope for a ramp?
    Ramps used as part of a means of egress shall have a running slope not steeper than one unit vertical in 12 units horizontal (8-percent slope).
  6. Can I make changes to a sealed set of plans already approved by Sussex County?
    No, you must have the Architect/Engineering redraw the changes & bring those new plans to our Commercial Plan Reviewer.