House or building remodels or expansions

Steps for house or building remodel or expansions

• Download the application

  Download the Application for Health Department Approval of Proposed Building Project (414 KB).

• Get approval before applying to the building department

  An Approved Application for Health Department Approval of Proposed Building Project is required prior to applying to the building department.

• Describe location of your septic components and site plan

  While preparing your application, it is important to accurately describe the location of all septic system components on your site plan. Search and download a drawing of your septic system (as-built drawing).
• What the inspector reviews in your plan

  Each application is reviewed by an inspector and receives a site visit. Examples the inspector are looking for includes:

  • Age of septic system
  • Condition of system
  • Type of system
  • Location of system as compared to area of remodel
  • Presence of a reserve drainfield area
  • Size of remodel
    • existing square footage vs. square footage being added
  • Use of addition
    • are bedrooms being added? If so, call the King County Septic Expert first! 206-477-8177
    • number of bedrooms equals occupancy equals size of septic system
  • Water source
    • a drinking water well requires certain setbacks to structures
    • structures must be served by an approved water source
  • As-built and past permit history
• Evaluation by a licensed septic professional

  Due to the scope of your remodel and condition, location and age of your septic system, you may be required to have the septic system evaluated by a licensed septic professional. The inspector will notify you in writing what this evaluation must include and what type of septic professional must be contacted.
• Upgrading or replacing your septic system

  You may also be required to upgrade or replace your septic system. For example, a house with an older septic system and your proposal is to tear the house down to the foundation and rebuild, it would require a new septic system. Call the King County Septic Expert 206-477-8177 to ask about your potential project.