Site Plans, Plot Plans, and Civil Drawings

What a Site Plan Shows

A site plan (sometimes called a plot plan) is a bird's-eye drawing of a property. It shows the land itself — not the interior of the building. Before a single footing is dug, every trade on a project uses the site plan to understand where the building sits, where utilities run, and how water moves across the lot. Learning to read one is a core skill for any construction worker.

Site plans are drawn to an engineer's scale, not an architect's scale. Engineer's scales divide inches into decimal parts (1" = 10 ft, 1" = 20 ft, 1" = 30 ft, etc.). Always confirm which scale is printed in the title block before you measure anything.

Property Lines and Legal Boundaries

The outer edge of a site plan is defined by property lines — the legal limits of the parcel. They are typically shown as a bold or dashed line and are labeled with bearings and distances (for example, "N 45°00'00" E, 120.00'".) This information comes from a survey. Never assume a fence or hedge is a property line; always refer to the drawing.

Setbacks

A setback is the minimum distance the building must be placed from a property line, as required by local zoning. Common setback types are:

• Front setback — distance from the front property line to the nearest face of the building
• Rear setback — distance from the rear property line to the building
• Side setbacks — distances from each side property line

Setbacks are usually noted on the site plan or in a zoning data table. Violating a setback can result in costly corrections or demolition orders. Measure setbacks with your engineer's scale directly from the building footprint to the property line.

Building Footprint

The building footprint is the outline of the structure as it meets the ground — essentially the shadow the building would cast straight down. It shows you the size and shape of the foundation and helps every trade locate their work relative to the structure.

Easements

An easement is a right that a party other than the property owner holds to use a portion of the land for a specific purpose. Utility easements are the most common on residential plans; they allow the utility company to access underground lines for maintenance. Easements are typically shown as a dashed rectangle or stripe with a label such as "10' Utility Easement." You must not build permanent structures inside an easement without approval — violations can require removal at the owner's expense.

Finished Floor Elevation

Finished floor elevation (FFE) is the height of the first finished floor of the building, expressed in feet above a datum (a reference point). On residential plans the datum is often assumed or tied to a benchmark on the street or property. FFE tells the concrete crew how high to set forms and tells drainage contractors how to slope the grade away from the building. Water must flow away from the foundation — if the grade is wrong, water intrudes and causes structural damage.

Contour Lines and Drainage

Contour lines connect points of equal elevation across the site. Key rules:

• Contour lines that are close together indicate a steep slope.
• Contour lines that are far apart indicate a gentle slope.
• Water flows perpendicular to contour lines, always moving from higher numbers to lower numbers (downhill).
• Where contour lines form a "V" shape pointing uphill, that is a valley — water concentrates there.

Reading contour lines correctly helps crews confirm that finish grading will direct runoff away from the building and toward the street or a drainage structure.

Utility Locations

Site plans show underground and overhead utilities using standardized symbols and line types. Common items include:

• Sanitary sewer line and cleanout (CO) — the cleanout is an access point for clearing blockages; locating it before excavation prevents accidental damage.
• Storm drain and catch basins
• Water service — the line from the main to the building
• Gas service
• Electrical service — sometimes shown as underground conduit

Always call 811 (Dig Safe / Call Before You Dig) before any excavation, even if utilities appear clearly on the drawing. Drawings may not show every line, and hitting an energized line or pressurized gas main is a life-threatening hazard.

When the Plan and a Verbal Instruction Conflict

Printed, signed drawings are the controlling document on a job site. If a supervisor gives you a verbal instruction that differs from a dimension on the site plan, stop work on that element, inform your supervisor that you see a conflict, and document it in the site log immediately. Note the date, time, your name, the supervisor's name, the specific plan reference (drawing number, revision, detail), the verbal instruction, and what action was taken. This protects the owner, the contractor, and you. Never quietly follow either instruction without escalating — building in the wrong location can cost tens of thousands of dollars to correct.

Safety on Site

• Wear your hard hat, safety glasses, and high-visibility vest whenever you are on an active construction site, including during layout work.
• Mark or fence any excavation made during utility investigation.
• Call 811 before excavation — it is the law in all 50 states.
• Keep plan sheets dry and legible; a misread elevation or dimension due to a smeared print is a safety and quality hazard.