10/19/2026
📌 Your layout crew and your model have to agree on where zero is
📍 The layout crew sets up the total station on project control and starts shooting hanger and sleeve points from the coordinated model. The first points land right. Then the ones near the old core wall start coming out off the beam they were drawn to hit.
🤔 Nothing is wrong with the model. The scan behind it was good too. It was registered to its own local origin and then dropped onto the project grid by eye. So the building in the model sits a little off the building on site, and nobody can say which one zero belongs to.
⚠️ Now every trade is laying out against a background that does not match the structure. Sleeves get drilled where the slab edge is not. Inserts go in, come out, and go back in. By the second floor the foreman has stopped trusting the model and the crew is back on tape measures.
✅ Settle control before anyone models a wall. Tie the scan to the same survey control the layout crew will use. Ask for the registration report and read it. Check the registered point cloud against known grid points before modeling starts, and again before coordination. While the scan and the building disagree in the office, fixing it is an edit. Once layout starts, it is rework.
📐 That is where good existing conditions work starts: laser scanning and Scan-to-BIM tied to project control whenever the job provides it, so coordination and shop drawings are built on the same building the crew is standing in.
🏗️ We remove field surprises by making existing conditions and trade coordination accurate enough to fabricate and install the first time.
Photo: Cvstr, CC BY 4.0, via Wikimedia Commons
