Small errors, expensive consequences
Anchor bolt as-built surveys have almost no tolerance for error. The steel is already fabricated to the plan, so any bolt located incorrectly can stop an erection crew cold. Most bad as-builts don't come from bad instruments — they come from a handful of avoidable field mistakes. Here are the ones we see most often.
1. Eyeballing center on bent bolts
The most common mistake is calling the center of a bent or leaning bolt by eye. Different crew members pick different points, and the error isn't caught until the office reviews the raw data. Use a fixed reference that locates the bolt's true base instead of its leaning top.
2. Not verifying plumb
A prism pole that isn't truly plumb reports an offset point, not the center. On a tall stick-up — the SDCJ handles up to 12" of projection — even a small tilt becomes a real horizontal error. Verify plumb with a level or laser plummet before every shot.
3. Inconsistent method across the crew
If two surveyors locate bolts two different ways, your dataset carries two different error signatures. Standardize the method — same jig, same reference point, same plumb check — so the data doesn't depend on who's holding the rod.
4. Wrong plate or adapter for the bolt size
Forcing a one-size approach onto bolts that range from ½" to 2" introduces slop. Match the reference to the actual bolt diameter so the fit is snug and the center is true.
5. Skipping the on-site QA check
Leaving the site without re-checking a few points and confirming your setup is the mistake that turns a small error into a return trip. Catching a problem on-site costs minutes; catching it in the office costs a day and a second mobilization.
6. Weak or unverified control
All the field care in the world can't rescue data built on control that doesn't close. Confirm your network meets the required standard — often First Order, Class I (1:100,000) for structural foundations — before you collect production points.
The common thread
Almost every item on this list comes back to consistency: the same reference, the same plumb verification, the same standard, every bolt, every crew member. A purpose-built locating jig bakes that consistency into the workflow. The SDCJ Anchor Bolt Locating Jig gives every crew member the same dead-center reference on bolts from ½" to 2", verifies plumb with an included laser plummet, and mounts a standard mini-prism — so your as-built data is repeatable by design. Learn more →