Protecting concrete floors during construction starts with the order of the work, not the product. Polish early, while the shell is open, and you pay for protection, plus fixing the spots where it fails. Polish last, and you pay for tight access, a second trip, and a floor stuck at the end of the punch list. On a 10,000 square foot shell, either way is real money.
You make this call on every job, with us or without us. So this is what we’d hand a job super who hired some other crew. It shows what each trade does to a finished floor and which covers hold up. And it lays out the order that keeps you off the phone with an owner about a stain in the lobby.
A quick way to decide:
- Finish the floor last if drywall, overhead rough-in, or a lift is still ahead of you.
- Finish the floor early if all that’s left is trim, touch-up paint, and fixtures. It wins by a lot, as long as you write and enforce a protection scope.
- Want one crew on the pour and the finish? See our page for builders and GCs.
Which comes first, the floor or the trades?
There are two good orders, and your trade list picks between them.
Finish early. We grind the floor and harden it once the roof is on but the building is still open. There are no walls to grind up against, no cabinets, and no fixtures. A 30-inch planetary head (the big grinding head on the machine) runs full passes end to end. Dust is easy to handle, since there’s nothing in the building yet to keep it off. It’s one trip instead of two, and the floor is done before the schedule gets tight.
The cost is that every trade after us works on a finished floor. You need a real protection scope and somebody enforcing it. And you’ll almost surely need a repair pass at the end anyway.
Finish last. You skip the protection cost and the protection failures, and the floor goes in clean at the end. The cost is access. Edge work is hand work. The edge of a 10,000 square foot rectangle runs about 400 linear feet, and every foot of it gets cut in with a 5-inch grinder on a knee pad. Add dust control in a building that now has finishes in it. Then add a floor sitting on the critical path between the last trade and the owner walk.
What does each trade actually do to a finished floor?
Every trade that follows the floor leaves its own mark. Some grind out and some are there for good. Know which is which, and your protection money goes where it counts.
| Trade | What lands on the floor | Does it come back out? |
|---|---|---|
| Drywall | Joint mud, texture spray, dropped screws | Mostly. Mud left for weeks leaves a ghost on a polished floor. |
| Paint | Overspray, roller drips, tape glue | Usually. Solvent stains and lacquers soak into pores and can show through. |
| Plumbing and pipefitting | Cutting oil, pipe dope, flux | No. The oil soaks in and comes back through whatever goes over it. |
| Steel and welding | Slag, spatter, burn rings | No. The heat changes the cement paste, and the stain goes deeper than the grind. |
| Lifts and boom equipment | Tire marks, hydraulic drips, outrigger point loads | Tire marks, yes. Hydraulic oil, no. Outrigger cracks are structural. |
| Material handling | Rebar chair drag, dropped pallets, stacked block | Scratches usually do. Chips become patches, and patches show. |
| Masonry cleanup | Acid wash runoff | No. Acid eats the paste and lightens it in blotches. |
The line is depth. A finish grind takes off about 1 to 3 millimeters. What sat on top comes off, and what soaked deeper stays. Welding heat, oil, and masonry acid all go deeper. And the crews who bring them, the welders, pipefitters, masons, and lift operators, have the least reason to think about the floor. So post the rules in writing. Don’t just ask at the foreman meeting.
Which protection holds, and which one just looks like protection?
Protection for a concrete slab is a line item in somebody’s scope, or it’s nobody’s job. And when it’s nobody’s job, it turns into cardboard.
| Material | Verdict |
|---|---|
| Cardboard | Not a plan. It soaks up a spill and holds it on the slab. Seams open, wheels tear it, and it stays wet for days after a sprinkler test. |
| Laminated fiberboard protection, seams taped | The working standard for foot and cart traffic. It rolls out fast, holds up, and comes up in one piece. |
| Breathable fabric-backed protection | The right pick over a slab that’s still drying out in its first weeks. |
| 6-mil plastic by itself | Traps water on a drying slab and leaves blotchy stains. It’s slick enough to make people fall, too. Use it as a vapor layer under something else, never as the surface people walk on. |
| Plywood over protection board | A must where a lift runs, an outrigger sets down, or material gets stacked. Point loads punch through anything softer. |
| Stick-on film on a polished or stained floor | Leaves glue behind, and glue on a densified floor is its own cleanup job. |
| Tape on the finished floor | Never. Tape protection to protection, and run a strip of protection up the base instead. |
Brand-name (proprietary) protection fits into those same rows. What counts is the kind of material and taped seams, not the name on the roll.
Protection is a line item, not a habit
A protection scope names the material, the area it covers, the day it goes down, and the day it comes up. It also names who owns each one. Pulling it up belongs on the punch list. Protection left down past the owner walk hides the very damage it was there to stop. The version that fails on every job is the one where protection is everybody’s job.
The sequence, in the order it actually runs
This is the order we’d hand a superintendent, and it works with any concrete sub in the market.
- Pour and cure. Nothing goes on the slab while it cures. A wet cure usually runs 7 days, and ACI 308 covers how. Traffic in that window weakens the top layer, and that’s the exact layer a polish will show.
- Dry in before anything else touches the floor. Roof on, walls closed, doors hung. Weather on a slab during finish work has no good fix. ACI 302 treats a closed-in building as a must for floor work, not a nice-to-have.
- Finish overhead rough-in. Everything that falls, falls first. Mechanical, electrical, sprinkler, and any spray-on insulation all go ahead of a finished floor, not after it.
- Grind and densify. We do the floor work with clean access and no finishes nearby to protect.
- Protect before the finishing crew rolls out. Not the next morning. The first stain always lands in the gap between a finished floor and a protected one.
- Run the rest of the trades on protection, with the rules posted at the door. Rule sheets go in the trailer and on the door, not in an email nobody opens.
- Pull protection, run the final passes, then close the floor. After that, only the punch list crew walks on it.
What does this look like when you are your own GC?
Owner-builders on a shop or a barndominium hit the same problem with nobody to enforce the rules. There’s no superintendent walking the building. And each sub works for you on their own, not under one contract that even mentions the floor.
The fix is a rule sheet taped to the man door. One page, 6 lines, where every sub walks past it:
- No pipe threading, cutting oil, or fueling equipment over the floor. Set a table outside.
- No welding or torch cutting over a bare slab, and a blanket down where sparks land.
- No lift or boom on the floor without plywood under the tires and every outrigger.
- Wipe spills when they happen, not at the end of the day.
- Nothing gets taped to the floor.
- Sweep up whatever you tracked in before it dries and gets walked into the pores.
Print it, sign it yourself, and hand a copy to each sub when they show up. Subs mostly follow a written rule and mostly forget a spoken one. That’s not about who they are. It’s about memory, on a job with four other things going wrong.
When is waiting until the end the right call?
More often than most finishing crews like to admit.
Some jobs beat up an early floor no matter what protection you buy:
- A tenant finish with a long list of trades
- A metal building where the shell and the inside work overlap
- An owner still deciding on the layout
Protecting a floor for 4 months costs you twice. You pay once for the material and the labor to lay it. Then you pay again for the repair pass at the end, because protection never stops all of it.
We watch how many trades are left and how much of the floor they need. Two trades working the edges is fine. Five trades stacking material in the middle of the floor is an order-of-work problem, and better protection won’t fix it. The floor goes last.
Why we will not promise to fix flatness on a slab we did not pour
Because that promise isn’t ours to make, and every crew that makes it is guessing.
Surface problems usually grind out. That’s leftover cure compound, light trowel marks, chipped joint edges, and most of what job traffic leaves. Height problems don’t. A big field that’s out of flat, joints that have curled up, and a slab that has moved go deeper than the surface. To grind them out, we’d have to cut deep enough to change how much stone shows and eat into the slab.
So we don’t put a flatness number on somebody else’s slab. We don’t write a line item called make it flat, either. What a grind can fix gets settled on the floor itself, with a 10-foot straightedge, by somebody standing on it. If your question is really about the slab and not the order of work, that’s the visit to set up.
The order is worth more than the product
Nobody has ever saved a floor by buying better protection after the fact. Get the order right, and picking the protection gets easy.
Working the same job? Our concrete subcontractor page for builders and GCs covers running the pour and the finish under one scope. Why the finish starts at the pour covers what the slab has to carry before anyone grinds it. The Pour-4-Polish method lays out the spec itself. And what to expect on project day walks the install hour by hour.
Talk the sequence through before you set the date
Bring your trade list and the date the building closes in. A ten-minute call is usually enough to tell which order costs less on your job.
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