Refers to a surface being perfectly vertical.

An elevation reference point created by the surveyor on or close to the property. Carpenters use this reference point when establishing or transferring elevation on a site or building.

A concept for right triangles stating that the sum of the squares of the legs of a right triangle is equal to the square of the hypotenuse. It is expressed mathematically as a2 + b2 = c2.

The direction indicated on construction drawings that shows how property lines and buildings are positioned on a site relative to compass or magnetic north.

A line beginning at one point and ending at another point.

Drawings that show the location of the building on the site from an overhead view, including contours, trees, construction features, and dimensions.

Based on the Pythagorean Theorem, this rule refers to the relative lengths of the sides of a right triangle.

A set of lines, typically horizontal and vertical, placed in a telescope used for sighting purposes. The lines meet in the center of the telescope.

An older-style level made from a length of clear flexible tubing filled with water. This type of level is typically used with graduated measuring rods.

The minimum distance, as required by regulatory authorities, between a property line and building lines.

A set of engineered drawings depicting the physical structure and components comprising the structure of a project.

Drawings that show the design of the project.

The average height of the surface of the ocean.

The elevation of the line of sight of the telescope relative to a known elevation. Determined by adding the backsight elevation to the known elevation.

A measurement of how much the ground varies from horizontal.

Specific points created on the site, where they are used as elevation and dimension reference points during site and building layout.

The recorded legal boundaries of a piece of property.

The longest side of a right triangle. It is always opposite from the right angle.

Angles that are perpendicular to one another, meaning they measure 90 degrees.

Markers used in surveying projects to designate grade or location information such as property boundaries, building corners, setbacks, and elevations.

A corner that is exactly 90 degrees.

Sometimes referred to as an optical level, this instrument is used to check, establish, and transfer grades and elevations. It is also used to set up level points over long distances.

A direction indicated on construction drawings that typically refers to the top of the page. 

A reading taken on a leveling rod held on a point in order to determine a new elevation.

Imaginary lines on a site plan that connect points of the same elevation. Contour lines never cross each other.

A short auxiliary scale set parallel to a primary scale.

A reading taken on a leveling rod held on a point of known elevation to determine the height of the leveling instruments.

The process of adjusting the slope or elevation of soil prior to and during building construction.

A drawing that identifies footing types and specifies the location and elevation of a building’s foundation.

This refers to a line that is perpendicular to the plumb only at one point on a line. This type of line does not follow the curve of the Earth.

A designated boundary line beyond which a building cannot extend. This line may not cross property lines and typically prevents buildings from being too close to a street or municipal property.

Permissible variations from a standard or specification.

Refers to a surface being perfectly horizontal.

A legal right-of-way provision on another person’s property. A property owner cannot build on an area where an easement has been located.

Also known as the dot laser, this instrument replaces older style plumb bobs by using lasers to project dots either vertically, horizontally, or at right angles to each other.

Angles formed by two lines or rays that measure exactly 90 degrees. A triangle that has a right angle is known as a right triangle. 

Physical structure that marks the location of critical survey points.