As-built drawings (also called record drawings) document the constructed condition of the project — the actual locations, elevations, sizes, and materials of the improvements as they were built, which inevitably differ from the design plans. They are required by virtually every jurisdiction as a condition of project acceptance, and they serve as the permanent reference for anyone who needs to know what is underground after the site is paved and occupied.

Who Prepares Them

As-built drawings are typically prepared by the project civil engineer, based on field information provided by the contractor and the surveyor. The process:

  1. The contractor marks up the plans during construction, noting any deviations from the design — changed pipe alignments, adjusted manhole locations, modified invert elevations, relocated utilities, and anything else that was built differently from the plans.
  2. The surveyor measures the as-built conditions — pipe inverts, rim elevations, utility locations, pavement elevations, and building pad elevations. This is called the as-built survey.
  3. The civil engineer incorporates the field data into a revised set of plans that shows the constructed condition. The as-built drawings use the same format as the design plans, with as-built information either overlaid in red or shown as a separate set of sheets.

What They Must Show

The specific content requirements vary by jurisdiction, but most agencies require as-built documentation of:

Storm Drain System

  • Pipe alignments (horizontal and vertical), with plan and profile showing the as-built locations
  • Pipe sizes and materials
  • Manhole and inlet rim elevations and invert elevations (for every pipe entering and leaving each structure)
  • Connections to the public storm drain system, with connection point coordinates and elevation
  • Detention/retention facility dimensions and as-built storage volumes

Sanitary Sewer

  • Sewer main and lateral alignments and invert elevations
  • Manhole rim and invert elevations
  • Cleanout locations
  • Connection point to the public sewer main

Water System

  • Water main alignment, size, and material
  • Valve and fitting locations
  • Fire hydrant locations and connection details
  • Backflow preventer locations
  • Connection point to the public water main

Grading

  • As-built contours or spot elevations at key locations (building pads, parking lots, drainage swales)
  • Retaining wall top and bottom elevations
  • Final earthwork volumes (cut and fill)

Dry Utilities

  • Conduit alignments and depths for electric, gas, telecom, and fiber
  • Vault and pull box locations
  • Transformer pad locations

Format Requirements

Most agencies accept as-built drawings in one of two formats:

  • Marked-up plans: The contractor's redline markups are transferred to a clean set of plans by the civil engineer. Changes are highlighted in a different color or line weight. This is the simpler and less expensive approach.
  • Fully revised plans: The civil engineer creates a new set of plans that reflects the as-built conditions. This produces a cleaner document but costs more to prepare. Some agencies require fully revised plans for public infrastructure (streets, water mains, sewer mains) while accepting marked-up plans for private improvements.

Digital submission (PDF and/or CAD files) is increasingly required in addition to or instead of paper copies. Some agencies require GIS-compatible data (shapefiles or geodatabase files) with attribute data for each utility feature. This allows the agency to update its utility atlas with the new installation.

When They Are Due

As-built drawings are typically required before:

  • Project acceptance by the public works department — for public improvements (streets, storm drains, water, sewer)
  • Release of the improvement bond — the bond is not released until the as-built drawings are accepted
  • Certificate of occupancy — some jurisdictions require as-built drawings before issuing the CO

The practical timeline: the surveyor performs the as-built survey within 2 to 4 weeks of substantial completion of the improvements. The civil engineer prepares the as-built drawings within 2 to 4 weeks of receiving the survey data. Agency review takes another 2 to 4 weeks. Total: 6 to 12 weeks from substantial completion to acceptance.

Common Problems

  • Contractor does not maintain redlines. If the contractor does not track changes during construction, the as-built information is unreliable. Require the contractor to maintain a set of redline plans on-site and update them daily.
  • Survey is performed too late. The as-built survey must be performed before the utilities are buried and paved over. Once the trench is backfilled and the pavement is placed, the only way to verify pipe locations is potholing, which is expensive. Schedule the as-built survey of underground utilities before backfill.
  • As-built drawings do not match the design plans in format. The as-built set should use the same sheet numbering, scale, and layout as the design plans. Submitting a different format makes it difficult for the reviewer to compare and increases the review time.