Glossary — Records
As-Built Drawing: Recording Buried Pipes and Cables
The drawing of what actually went into the ground. For buried services it is the only reason the next crew does not have to guess.
Quick AnswerAn as-built drawing is a record of what was built, measured during or after construction. It shows the final position, depth, size and material of every element, including changes from the design. For buried water pipes, cables and ducts it fixes where the line lies, with pits, depths and crossings, so the next excavation does not rely on memory. See: GPR, SUE & Land Survey Glossary explained.
What is the meaning of an as built drawing?
An as-built drawing shows the work as constructed, not as designed. On each construction project, field crews record every deviation, extra bend, depth change and added chamber, and a surveyor measures the final positions. The result replaces the design drawing as the reference for operation, maintenance and every future dig near the asset.
Some contracts distinguish a record drawing, compiled by the designer from the contractor's marked-up prints, from an as-built measured on site. In utility work the measured version is what matters.
What should an as-built show for buried services?
| Item | Why it matters |
|---|---|
| Alignment with coordinates | Lets anyone find the line again, on site or in GIS |
| Depth or cover at intervals | Sets safe digging and drilling depths nearby |
| Pits, chambers and joints | Access points and their numbering |
| Lengths between pits | Checks quantities and fault-finding distances |
| Crossings with other services | Clearances that must be kept by later works |
| Material, size, duct count and colour | Identification when the line is exposed |
| Date, surveyor and method | Shows how far the record can be trusted |
Where an as-built is checked afterwards with radar, the scan is priced per metre; see the GPR survey cost calculator for an estimate.
How is depth recorded?
Best while the work is open or still being drilled. In an open trench the crew tapes cover at regular intervals. In horizontal directional drilling the drill-head sonde gives depth at each rod, so the bore profile is captured as it happens. Checking an old line later is possible with ground penetrating radar (GPR), a geophysical survey method that reads buried services from radar echoes, but it is less exact. The line shows as a hyperbola whose depth depends on calibration (see: GPR Hyperbola). That calibration rests on soil velocity; read Dielectric Constant (Relative Permittivity) in GPR for why.
An example from a duct route
A three-shot duct route runs through pits P1 to P4 with shots of 120, 150 and 180 m. The plan gives each pit its coordinates; the profile shows the bore at about 1.9 m and its clearance above a 300 mm sewer whose top sits at 2.4 m. A later contractor planning a drain in that street reads the clearance from the drawing, a far more cost-effective step than finding it with a bucket.
Cover or level: what should an as-built record?
Both, but the reduced level of the service is what stays true. Suppose a duct was recorded in 2019 with 1.20 m of cover. Two resurfacings later the road is 8 cm higher, so cover is now about 1.28 m, and a GPR check reads close to 1.3 m. Nothing is wrong with the duct or the scan; the surface moved. Had the as-built given the duct's level above a benchmark as well as its cover, the later contractor would have known the duct had not shifted. Our profiles therefore show ground level, service level and cover together.
Common as-built mistakes
Most poor as-builts fail through omission, not outright error.
- Re-issuing the design. An as-designed drawing stamped "as built" is the most dangerous record of all.
- No depths at bends. Depth taken only at pits misses dips and humps along a bore.
- Missing coordinates. Offsets from kerbs and buildings disappear when the street is rebuilt.
- Renumbered pits. Pit numbers that differ between drawing and site make fault-finding slow.
- Crossings left out. Clearances to other utility lines are what the next contractor needs most.
What a Mezux as-built pack contains
A plan, a profile and the schedules behind them, in DWG, PDF, Excel and KMZ. The plan shows the route with pit coordinates and lengths between pits, and the profile shows ground level, service level and cover. A pit schedule lists each pit's ID, type and coordinates, and a crossing table lists each service crossed with its measured clearance. For newly installed utilities ASCE 75-22 sets out how such as-installed data should be recorded and exchanged, while ASCE 38-22 covers the investigation of services already in the ground.
Is a field sketch an as-built?
Not by itself, but it is where every good as-built begins. Crews often keep a hand-drawn sheet of each shot or trench, with pit numbers, lengths, depths and notes on obstructions. That sketch is valuable, because it records what the crew saw while the ground was open. It becomes an as-built only when its positions are tied to coordinates, its depths to levels, and its contents drawn to a standard that someone else can read years later. The crew's sketch and the data collected by the surveyor together form the source for the measured drawing, and the sketch stays on file with the final pack.
Formats
DWG and PDF for the drawing, with coordinates in Excel and a KMZ or shapefile for GIS. Investigations of underground utilities before a new line goes in are explained in SUE survey, in short. Surveyed boundaries for the same corridor are part of land survey services by Mezux Touch.
To get as-builts measured on your route, share your project details.
Frequently asked questions
Who prepares the as-built drawing?
In most cases the contractor, from site records, with a surveyor measuring final positions. The owner checks and accepts it.
Can an as-built be made for an old line?
Yes: we detect and map it by locating and surveying, but depth will be less certain than one recorded during construction.
Is a KMZ alone enough as an as-built?
Rarely. It shows the route but not depths, pits and crossings in a form contractors can use. Provide it with the drawing.
Should an as-built show cover or level?
Both. Cover is what a digger needs today; level above a benchmark stays valid when the surface is raised or lowered.
How soon after construction should the as-built be made?
During construction, ideally, while trenches are open and bores are being drilled. Later surveys can locate the line but with less certain depth.
Who should keep the as-built?
The asset owner, in its records and GIS, with copies to the local authority where rules require it, so future works can find it.
Get your route recorded as built
Written by Saniya Parveen · Technically reviewed by Rahul Rai · Updated 8 November 2026