How to read civil drawings

Civil drawings cover everything that happens outside the building footprint: site grading, underground utilities, roadways, stormwater management, and erosion control. These are typically the C-series sheets and are among the first to be used during construction since sitework precedes building construction.

Step 1: Understand the Site Plan

The site plan (typically C-100 series) provides the bird's-eye view of the entire project. Before reviewing details, orient yourself with these elements:

• Property lines and legal boundaries, defines the limits of the project site
• Building footprint, the outline of the proposed structure(s)
• Setback lines, required distances from property lines where building is prohibited
• Easements, areas reserved for utility access or public use
• Access roads and driveways, vehicular circulation and entry points
• Parking areas, spaces, drive aisles, ADA-accessible stalls
• North arrow and scale, essential for orientation and measurement
• Benchmarks, known elevation points used as references for all vertical measurements

Step 2: Read Contour Lines

Contour lines represent ground elevation. Each line connects points of equal elevation, creating a topographic map of the site. Mastering contour reading is essential for understanding drainage and grading.

Step 3: Follow Utility Plans

Utility plans show underground infrastructure connections. Each utility type uses a distinct line pattern:

Pay special attention to utility crossing points. Where pipes cross each other, verify that there is adequate vertical separation (minimum 18" in most codes) and that the water main is above the sewer.

Step 4: Check Grading Plans

The grading plan shows how the existing site will be reshaped. Critical elements include:

• Spot elevations, specific point elevations at building corners, curb tops, flow lines, and grade breaks
• Slope arrows, triangles or arrows showing drainage direction with percentage noted
• Retaining walls, where grade changes require structural solutions
• Swales and berms, shallow channels and raised areas for directing surface drainage
• Building pad elevation, the finished floor elevation (FFE) at the building entry
• ADA-compliant routes, accessible paths from parking to entries must not exceed 5% running slope

Step 5: Review Erosion Control

Erosion and sediment control (ESC) plans are required for most projects disturbing more than one acre. They outline measures to prevent soil from leaving the site during construction.

Step 6: Understand Paving Details

Paving plans and details specify roadway, parking, and sidewalk construction:

• Pavement sections, cross-section showing subbase, base course, and surface course thicknesses
• Curb and gutter details, curb height, gutter width, and drainage slopes (typically 1-2% cross-slope)
• Striping and marking plans, parking space dimensions (typically 9'x18'), drive aisle widths, and accessibility markings
• ADA details, accessible parking space dimensions, access aisle widths, curb ramp slopes (max 8.33%)
• Pavement joints, saw-cut and expansion joint locations for concrete paving

Common Civil Drawing Symbols

Sources