Find the lift's foundation page before the pad gets graded
Every lift ships with a manual, and somewhere in it is a page giving the concrete the manufacturer wants under the columns: a thickness, a strength, and an area of sound concrete around each anchor. That page is the number. We do not guess at it, and we are not going to talk you out of it. Bring it to the estimate, or send a photo of it, and we build to what it says.
If the lift is not bought yet, that is better still. Tell us the make and the capacity you are looking at and we will form for the heavier end of what you are considering. Concrete put in the ground while the forms are open is cheap. Concrete added to a finished floor is not.
Mark where the columns land while the ground is still open
The second thing we need from you is position, and it deserves more thought than it usually gets. Once the pads are in, the lift is going where the pads are. So we chalk it on the ground before the base is finished and walk it with you.
Think about the length of the longest vehicle you will put on it and whether the overhead door still closes behind it. Think about which side you walk down with a transmission jack, and whether the arms swing clear of a post or a wall. Think about whether a workbench or a second bay is going along that wall in a few years. A shop floor gets poured once and lived on for a long time, and a lift set two feet off from where it should have been is a daily irritation that nobody can fix later.
The pads and the floor go in as one pour
With the forms open we dig the pad footprints down below the floor line, set rebar in them, and hold that steel up on chairs so it ends up inside the concrete instead of lying on the stone. The ground under those pads gets the same treatment as the rest of the floor, stripped to firm subgrade and brought back up with stone compacted in layers, because a thick pad sitting on soft ground is only a thicker thing to settle.
Then it pours in one go. Floor and pads together, wet into wet, so there is no seam between a pad and the slab around it. That part matters. A pad poured separately later is a plug sitting in a hole, and the joint around it is a ready made line for a crack to follow. Poured with the floor, the whole thing acts as one piece of concrete.
The rest of the floor carries on at five inches and gets saw cut on a joint grid the way any shop floor does. We lay that grid out with the lift in mind, so a cut line does not run straight through a column pad.
Anchors go in after the floor has cured, on the manual's layout
The lift's own anchors get set once the concrete has come up to strength, drilled and installed the way its instructions say. That step belongs to whoever assembles the lift. Our part is making sure that when they drill, there is enough sound, properly cured concrete in the right place for those anchors to hold, and that no joint or slab edge is sitting where a bolt wants to go.
If your shop floor is already down and you are wondering whether it will take a lift, we cannot tell you from a photo. Thickness can be checked, and if it comes up short the real options are cutting out and repouring the two pad areas or choosing a lift the floor suits. Either way that is a phone call and a look at the building, not a guess.