Price lightning wait time as logged stopped hours multiplied by crew size and the loaded rate, allowing at least 30 minutes after the last thunder.
Key takeaways
- Keep storm waiting time separate from production hours.
- Record the rumbles, work stop and work restart.
- Check crew size and the loaded rate against the logged time.
Why this wait belongs on its own line
Outdoor crews stop when thunder is close, and every stop costs money. An hour a crew spends waiting in a truck or trailer is paid time with no output. If the estimate leaves that time out, the job loses money on every storm day. If the owner's schedule assumes the crew works straight through, the two sides will argue about every idle hour once the invoice arrives.
The way out is to treat the post-storm wait as a named line in the labor build-up. It has a minimum length, a known trigger, and a logged end point. That makes it something an estimator can price and an owner can check.
The length comes from lightning safety guidance. The Canadian Centre for Occupational Health and Safety (CCOHS) says to stay inside for 30 minutes after the sound of thunder ends. The National Weather Service (NWS) gives the same count for outdoor activity: wait 30 minutes after the last rumble of thunder before resuming play. Both agencies give the same minimum wait. That is why this post uses 30 minutes as the working figure.
What the safety sources say
Read the sources before you write a clause based on them, because they make three separate points.
The first point is about odds. The CCOHS page says the odds of getting struck by lightning are less than one in a million. It then cites Environment Canada (2021) for the fact that lightning kills 2 to 3 people every year in Canada and injures another 180. Low odds for one person still add up over a whole population. The guidance sets a minimum count instead of leaving the call to how the sky looks, and an estimator should price the logged wait, not a judgment made by whoever is eager to get back out.
The second point is about shelter. The NWS says that there is little you can do to substantially reduce your risk if you are outside in a thunderstorm. It also says that the only completely safe action is to get inside a safe building or vehicle. For a crew, that means the safe position during a storm is inside a safe building or vehicle, not an open or partly covered work area. The estimate should not assume crews keep working in the open when thunder is near. The wait is time spent in shelter, and the price should reflect that.
The third point is that the same 30-minute count shows up across outdoor activity, not only one kind of work. The NWS tells beachgoers to wait 30 minutes until after the last rumble of thunder before going back to the beach. It tells cyclists who are near a safe building to pull over and wait 30 minutes after the last rumble of thunder before resuming your ride. When an owner asks why the wait is 30 minutes and not some other figure, this is a useful answer: the count is the one the NWS uses across several settings.
Why the clock restarts with every thunderclap
The wait runs from the last thunder, not the first. A new rumble becomes the new last thunder, so the 30 minutes starts over from that point.
This matters most for storms that linger. A storm that rumbles on for a long stretch can cost more crew time than a brief one, because the clock keeps restarting. Suppose the last rumble the crew hears comes at a given time. The earliest return under this rule is 30 minutes after that rumble. Price the logged time from the work stop through the return, including the period when thunder continues.
There is a practical catch. A crew lead usually cannot tell that a rumble was the last one until the quiet period has already run. The way to handle this is to treat every rumble as a possible last one. Keep the crew sheltered after each rumble, and let the wait run from whichever rumble turns out to be the final one. Write the times down. The log is where the final time is recorded, and it is the record an owner will check.
How distance helps, and where it stops
The CCOHS page gives a simple way to judge distance: each second between the flash and the thunderclap represents about 300 metres. To estimate how far away the flash is, count the seconds between flash and thunder and multiply by 300 metres.
A site lead can use this count to tell the superintendent how close the storm is and whether it seems to be moving toward the work. That information helps the people who decide when to stop. It also helps owners understand why work stopped when the sky still looked fine overhead.
Do not use distance to shorten the wait. The guidance ties the clock to the sound of thunder, not to a distance you worked out after the fact. Any stop rule based on distance is a site safety decision for the contractor and its safety lead.
Build the wait into the labor line
Start by counting storms from your records, not from memory or hope. Use weather history for the region and season and the site's record of past stops.
Once you have a count, the price of each wait is simple arithmetic. Wait cost equals wait hours multiplied by crew members, multiplied by the loaded hourly rate. Check the rate alongside your paid-time and overtime costs.
For one stop, price the logged time the crew was actually stopped, including at least 30 minutes after the last thunder.
Illustrative example of wait cost
Here is an illustrative example, not a real rate or site. A crew stops after thunder is heard, and the logged wait is 30 minutes after the last rumble, with no further thunder. At an illustrative loaded hourly rate of 60, the wait costs 300. Repeat that for every stop in the job's records, and the wait adds up to a visible total on the labor line. Estimators can run the same method with their own crew sizes and rates.
Some rules keep this line honest:
- Price the wait as its own line. Keep it apart from production hours so nobody can hide it in a blended rate.
- Price only the idle time. If some tasks can truly be done under cover, count only the hours when the crew is stopped. Do not assume crews can keep working indoors just because a building is nearby.
- Add restart time only when you expect it. If the crew needs time to get back to work after the wait, write it as its own line and explain it.
- Keep crew sizes current. The wait is multiplied by people, so a crew change in the middle of a job changes the price.
Scheduling matters as much as pricing. If your records show storms at a particular time of day, you can plan tasks that are safe to pause midway for those hours and keep tasks that need long unbroken work for other hours. This is planning advice, and it only works if the crew can actually leave a task at a safe point.
Scenarios that change the estimate
Most jobs will not see one clean storm. Price each pattern separately.
One storm, one stop. The simplest case. Price the logged stopped time through the crew's return.
A storm that stops and restarts work several times. Each separate stop gets its own count. Three stops in one afternoon means three logged waits, each including the minimum after its last rumble. Do not add them into one block, because the logs will not match a block.
A storm that rolls through more than once in a day. Treat each cycle as its own event. The log for each cycle should show the rumbles, the stop time, and the resume time, so the owner can check each one separately.
A storm the crew never hears. The trigger in the sources is thunder that is heard. A storm the crew never hears gives you no thunder to count from. The site may still choose to stop for other reasons under its own safety plan, and those stops should be priced and logged separately, with the reason written down.
Several crews on one site. If more than one crew shelters at the same time, each crew's hours need their own count and their own crew size. Do not combine them into one number that is hard to check.
Who calls the stop
Settle who calls the stop before the job starts, and write it into the site safety plan.
A workable setup names one person as the thunder watcher. That person has the authority to call a stop, starts the clock from the last rumble they hear, and logs the times. Everyone on site should know who this is and what the rule is. The crew should know who authorizes its return under the site safety plan. The watcher's log records the timing.
Production pressure is the main risk here. A foreman who wants to finish a pour before a storm can be tempted to delay the stop, and a crew that wants to go home can be tempted to return early. Neither is a reason to shorten the wait.
Making the wait easy to verify
Owners check these hours against the site, and a wait line that is just a number is hard to check. Have the crew lead log three times for every storm stop:
- the time of each rumble heard during the stop
- the time work stopped
- the time work resumed
A sample entry might read: last rumble heard at the time written first, work stopped within a minute of that rumble, and work resumed after the full 30-minute wait. The resume time falls after the earliest return time, which is consistent with the rule.
Owners can then check the following:
- No early return. Compare the resume time with the last logged rumble.
- Longer waits can meet the minimum. The CCOHS wording is remain in the sheltered area for at least 30 minutes after you hear the last thunder, so a longer wait can be right. A new rumble changes the last-thunder time; it does not explain extra time after that minimum.
- Hours tie to the log. The billed wait should equal the logged wait multiplied by crew size.
- Gaps are questions, not verdicts. A gap in the log is something to ask about. It is not proof of anything until someone has looked into it.
If you are an owner, ask for the log format before the job starts, not after. A simple paper or phone sheet with three times for each stop is enough. Review the logs on a regular schedule, not only when a dispute comes up, so both sides see the same record while the work is still happening.
Talking to owners about the line
Owners sometimes see a storm wait as lost time. The best way to answer that concern is with the rule, the log, and the math together. Show the owner the 30-minute count and the sources behind it. Show the log for a sample stop. Then show the arithmetic: wait hours, crew size, and rate.
Explain that the wait is not padding. It is the time the safety guidance says a crew should stay sheltered after the last thunder. If the owner wants to reduce storm cost, the useful conversation is about scheduling and about which tasks can be paused safely, not about cutting the wait itself.
Agree on the log format and the review schedule in writing before the job starts. An owner who has seen the log every week is far less likely to dispute the total at the end. The same log protects the estimator, because a wait with clear times and a clear count is easy to defend.
Writing the wait into the bid
Put the rule in the bid so nobody has to argue about it later. A workable clause says that billable time is the logged shelter time, includes at least 30 minutes after the last rumble logged by the crew lead, and is billed as crew hours with the log attached. Keep the clause short. Long clauses invite disputes about edge cases that the log can already settle.
Two cautions apply. First, the price is not the safety plan. Who decides to stop work, who watches for thunder, and where the crew shelters belong in the site safety plan. The bid can refer to that plan, but it should not replace it.
Second, contracts handle weather in different ways. The wording of your contract decides whether the wait is billable or is a cost you carry. Check that wording before you assume the wait is recovered. If the contract is unclear, raise it before the bid goes out, not during the storm. Include this line in your construction estimate audit.
Your next step
Today, check a past storm stop: compare the logged shelter time, crew size and loaded rate with the amount carried in your estimate.
Related guides: Ladder setup: 4 figures to check before crew hours · Sick leave burden: 3 checks before pricing crew hours.
Questions
Is each stop a flat half-hour cost?
No; price the actual logged stopped time, including the period while thunder continues and the minimum wait afterward.
Does pricing the wait make it billable?
No; the contract wording decides whether the wait is recoverable or a cost you carry.