A Geofence Time Clock for Construction Crews
Set a geofence around each job site, and clock-ins from outside the fence get blocked at the punch. Here's how a construction crew keeps hours honest and tied to the right job.
JULY 5, 2026 · BY THE CLOX TEAM
You run more than one job at a time. A framing crew here, a slab pour across town, a couple of subs who float between sites, and a few guys who start before you have finished your coffee. When Friday comes and you build payroll, you're trusting that the hours on the sheet match where people actually were. On a construction schedule, that trust gets expensive fast.
A geofence time clock closes part of that gap. You draw a boundary around a job site once, and when a worker clocks in from outside it, the punch doesn't get created. This post walks through how that works in Clox, what it doesn't do, and how project tags keep hours tied to the right job so your cost tracking stays clean.
01
The construction problem this solves
Most time-tracking headaches on a job site come down to two questions. Was the person actually on site when they clocked in, and are their hours getting charged to the right job. A geofence answers the first, because the clock-in has to come from inside a worksite with a real boundary on a map, and the project tag on the shift answers the second.
- A guy clocks in from the truck on the highway, ten minutes before he reaches the site. That's ten minutes of paid time per person, per day, that never happened on the job.
- Someone is running late and texts a buddy to punch them in from the other job across town. The hours look fine on the sheet and land on the wrong cost code.
- A sub bills you for a full day but rolls in at nine. Without a boundary tied to that specific site, you have nothing to check the timesheet against.
- Two jobs are active and hours get mixed between them, so your job costing on both is off by the end of the week.
None of these are dramatic. They're the small, quiet leaks that add up across a crew of ten over a full season. A geofence per job site turns each clock-in into a location-checked event, and the project tag ties it to one job, which is exactly what cost tracking needs.
02
How the geofence works in Clox
You set up each job site as a worksite. On the map, you drop a pin on the site and draw a radius around it. The default is around 200 meters, which covers a typical lot with room for a parking area and a trailer, and you can widen or tighten it per site. A tight urban infill job and a sprawling grading job don't need the same fence, so you adjust each one to fit.
Enforcement is per employee, not all-or-nothing. You decide which crews the fence applies to. Your framers who spend the day on one slab can be held to that site's boundary. The super who drives between four jobs, or the equipment operator who is genuinely mobile, doesn't have to fight a fence all day. You're not choosing between honest hours and a workable day for the people who really do move around.
When the fence is enforced for a worker, a clock-in from outside it is blocked at the punch. The off-site punch is never created in the first place. This is the part worth slowing down on. A lot of tools only warn, which means the bad punch still exists and lands on you to catch and fix later. Clox blocks it, so there's nothing to clean up after the fact.
Blocked, not just flagged
If an enforced worker is outside the fence, the clock-in doesn't go through. You're not reviewing a bad punch after payroll. It never got created.
The accuracy grace, so honest workers are not stuck
Phone GPS isn't surgical, especially near steel, tall buildings, or under a metal roof. If Clox blocked every punch that landed a few feet past the line, you would have honest guys stuck at the gate. So a punch just outside the radius can still land if it falls within the phone's reported accuracy, capped at 100 meters. Those allowed-but-marginal punches get flagged for you with an "Off the worksite" readout, so you can eyeball them at approval instead of arguing about them at the fence.
A fix too coarse to trust, worse than about 500 meters and wider than the fence itself, gets rejected as too inaccurate. That prevents a garbage location reading from sneaking a punch through just because the phone wasn't sure where it was.
The three flags you see at approval
When you review hours, Clox surfaces a few flags in priority order so you know what to look at first.
Review flags, in the order Clox prioritizes them.
Early starts, dead zones, and offline sites
New construction rarely has reliable signal. A guy who starts at six on a site with no bars still needs to clock in. Clox handles that offline. The punch is saved on the phone with its real timestamp and location, and the phone warns the worker right away if they look off the job site. When signal comes back, it syncs, and the server refuses an off-site punch, which never lands on the timesheet. So the boundary still does its job in a dead zone, and the early start is recorded at the minute it actually happened.
Shared tablet at the trailer
Some crews prefer one shared tablet at the trailer instead of everyone using their own phone. Clox has a kiosk mode for that, where each worker taps in with a PIN. Kiosk captures no GPS. The identity there is the on-site tablet plus the worker's PIN, not a location reading. It's a fair trade for a shared device that lives on the job, and it's worth knowing the geofence check only applies when people clock in from their own phones.
03
Tying hours to the right job for cost tracking
This is where the project tag earns its keep on construction. Because the worker picks the job at clock-in, the hours are attached to that job from the start. You're not asking someone to remember which job they were on or hand-sorting a timesheet at the end of the week. When you run two or three jobs at once, that separation is the difference between real job costing and a guess.
Clox is time tracking for field crews across the board, not just a fence. Clock-in is one tap. Overtime and breaks are calculated automatically, which matters when a crew pushes past forty on a deadline. And the exports are payroll-ready for QuickBooks, Gusto, ADP, and Paychex, so the honest, job-tagged hours flow straight into how you actually pay people. You can see the whole pricing picture on the pricing page.
04
Be honest about the limits
A geofence is a strong deterrent. It's not a guarantee, and any tool that tells you otherwise is overselling. The location comes from the worker's phone. That's the plain truth of how phone-based GPS works, and it's worth saying out loud before you buy anything.
What that means in practice: a determined person with the right tools can try to feed a phone a fake location. Clox is built to catch the obvious versions of that. A device reporting a mock GPS provider gets flagged, an impossibly far jump from the same worker's last clock-in gets flagged, and a location too coarse to trust gets rejected. Those defenses raise the effort and lower the payoff. They don't turn a phone into a tamper-proof badge reader, and we're not going to pretend they do.
What a geofence is and is not
It's a deterrent that blocks the easy, casual off-site clock-in and flags the suspicious ones for you. It's not foolproof, because the location is reported by the worker's phone. Buy it for the deterrent, not for a guarantee.
The reason we're blunt about this is simple. On a job site, trust is the whole point, and a tool that oversells itself burns that trust the first time it fails. A geofence stops the loose habits, like the clock-in from the truck, and gives you clean flags to review. That's a real, useful thing on its own.
05
Common objections from the field
My guys will say this is tracking them all day
It's not continuous tracking. The location is checked at the punch, when someone clocks in. It confirms they were on the job at that moment. It doesn't follow them around the site or off it. That distinction matters a lot to a crew, and it's worth telling them straight so it doesn't become a morning fight.
What about the subs I do not control
If a sub clocks in through your Clox worksite, the same fence applies to them. That gives you a location-checked record tied to your job to hold their billed hours against. You can't force a sub onto your system, but for the ones you can, the geofence gives you something concrete to check against a full-day invoice.
My site is huge and the fence is too tight
The radius is per worksite and adjustable. A large grading or civil job can have a wide fence, and a tight downtown lot can have a small one. You're not locked into one size across every job, so the boundary fits the site instead of the site fighting the boundary.
Half my crew has no signal at the site
Covered above, and worth repeating because it's the most common construction blocker. Offline punches save on the phone with the real timestamp, and a clock-in also saves the worker's location. The worker is warned right away if they look off site, and the server refuses an off-site clock-in when it syncs, so it never lands on the timesheet. Dead zones don't break the geofence and don't lose the early start.
06
Trying it on your next job
You can set up a worksite and test the fence on one job before you roll it out to the whole crew. Clox is free for 14 days with no credit card to start, and there's a 30-day money-back guarantee if it doesn't fit how you run jobs. You can start a free trial and draw your first fence in a few minutes. The iPhone app is on the App Store, and anyone on your crew can also clock in from a phone browser at app.getclox.com, so you can put it in front of a real crew today.