Drawing Seattle Site Plan

How to Draw a Site Plan

A site plan is a detailed map of your property, created to scale, which outlines both existing and proposed structures, as well as other pertinent information required for project review. In Seattle, you can either draw this yourself or hire a professional, such as a septic designer or architect. Regardless of who creates the plan, you are responsible for ensuring its accuracy and completeness. Here’s a step-by-step guide to drawing a site plan according to the City of Seattle standards.

1. Determine Lot Shape and Dimensions

Begin by obtaining a parcel map from the City of Seattle. This map will show the shape and some dimensions of your lot. If your lot was created through a subdivision, the city might also provide a plat map with precise dimensions and shape.

2. Choose the Right Size and Scale

Your site plan must be drawn to scale, meaning that measurements on the plan correspond to real-world distances. Use an engineer’s scale for this purpose. For example, 1 inch on the plan might equal 20 feet in reality. The City of Seattle requires this scale for site plans.

  • Standard Paper Size: The site plan should fit on an 11” x 17” sheet of paper, with a scale that allows for clear detail.
  • For Large Lots: If your lot is too large to fit on a single sheet, you have two options:
    • Continuation: Extend the plan onto additional sheets, marking a clear “match line” where the sheets align.
    • Break Line: Use a break line to shorten the lot boundary on the paper. Ensure this does not obscure any project-relevant information.

3. Drawing the Site Plan

Include the following items in your site plan, ensuring each feature is labeled and dimensions are provided where applicable:

  • North Arrow and Scale Indicator: Clearly mark the direction and scale of the plan.
  • Site/Parcel Address: Include the full address of the property.
  • Parcel Number: Provide the unique parcel identifier.
  • Property Lines: Dimension all property lines, including those with break lines.
  • Property Owner: List the name of the property owner.
  • Sewer Service Line: Show its location on the plan.
  • Septic System: Indicate where the septic tank and both primary and reserve drain fields are located. Ensure you have the required septic system approval from the Seattle-King County Public Health before applying for a building permit.
  • Water Service Line: Mark its location.
  • Storm Service or Infiltration System: Include this in your plan.
  • Adjacent Street Names: Label the streets next to your property.
  • Easements: Show the location of any private or public easements.
  • Driveways: Indicate both the location and dimensions.
  • Existing Trees: Show all trees on-site, including their drip lines and trunk diameters.
  • Natural Buffer Area (NBA): Mark the boundary of any natural buffer areas.
  • Critical Areas/Buffer Zones: Identify any critical areas or their buffers.
  • Shorelines: Note the ordinary high water mark (OHWM) if applicable.
  • Water Features: Include streams, drainage areas, and seasonal swales.
  • Topographical Contours: Display contour lines at 2-foot vertical intervals. If specific elevations are unknown, establish a zero elevation point as a reference.
  • Footprint of Structures: Draw and label the footprint of both existing and proposed structures as “Existing,” “Proposed,” or “To be Removed.”
  • Dimensions of Structures: Provide dimensions for all sides of both existing and proposed structures.
  • Setbacks: Indicate the distances from property lines to structures.
  • Distances Between Structures: Show the distances between existing and proposed structures.
  • Additional Features: Include all decks, patios, retaining walls, bulkheads, etc., labeled as “Existing,” “Proposed,” or “To be Removed.”

By following these guidelines, you will create a comprehensive site plan that meets the City of Seattle’s requirements and facilitates the review of your project.