Winter crew labor hours: 4 cold-stress figures

Key takeaways

• Record conditions for each outdoor work block.
• Separate wet, exposed tasks from dry, sheltered work.
• Price warm-ups, breaks, clothing changes and travel to warmth.
• Write down the assumption behind each added hour.

A crew that sets forms on a mild, still morning works at a different speed than the same crew in a cold wind across an open site. Hands slow down, breaks get longer, and people need time to warm up before they are safe on a ladder or a saw. Many estimates handle this with a flat winter allowance, and when an owner asks where the allowance came from, the answer is often a shrug.

This post shows how to make that allowance traceable. It uses four cold-stress figures from CCOHS. They cover wet skin exposed to wind, sustained wind, work-warming and extended warm breaks. Each one can become a schedule line or an hour count, and each has a source you can point to when the owner asks.

The steps follow the order you would use them on a job: read the conditions, adjust them for wet crews, check the wind, plan the warm-ups and breaks, then cover clothing and the estimate itself.

One caution first. The figures below come from the pages linked in each section, and those pages are guidance rather than a complete rulebook. Cold-work duties are set by regulators and employers, and they can differ from one place to another. Treat the numbers as inputs you can defend, and check the rules that apply where your crew works before you write any of them into a contract.

1. Start with wind chill, not the air temperature

Most crews are given the air temperature, and most forecasts lead with it. That number is a starting point, but it does not drive cold stress on its own. The CCOHS guidance on cold working is built around wind chill temperature, which it abbreviates as WCT. The WCT is determined from an air temperature measurement, so air temperature still matters, but wind changes the reading you work from. CCOHS: Cold Environments - Control Measures The first input in any winter estimate is therefore a wind chill reading for the hours the crew will be outside, not a bare thermometer reading.

Pull the forecast for the actual work window. A job that runs from 7 a.m. to 3 p.m. may have a cold, calm morning and a windier early afternoon, and a single daily low can hide both. Write one line for each work block in the estimate: the hours, the forecast air temperature, and the forecast wind for those hours. Those lines become the base for every adjustment that follows.

Here is what one line might look like: "Block 2, 11 a.m. to 3 p.m., forecast air 2°C, sheltered, measured reading applies." A second line for the same day might read "Block 1, 7 a.m. to 11 a.m., forecast air -5°C, wet crew, adjusted reading applies." Those two lines cover equal time, but may need different labor-hour allowances.

Pick a forecast source that both you and the owner accept, and record which one you used. Forecasts change between bid and start, and when they do, the estimate should show which reading it was built on. That way the owner sees why the hours moved instead of assuming the number was padded.

The reading also needs checking during the job. Crew leads should look at conditions at the start of each block, not only when the estimate was written. A forecast is a plan, and the crew is the one standing in the wind.

2. Apply the 10°C wet-skin adjustment

The second step changes the reading when the crew is wet. The guidance is direct on this point: "Note that if the skin is wet and exposed to wind, the air temperature measurement used to determine the WCT should be 10°C lower than the actual temperature." CCOHS

Use the adjusted air temperature to determine WCT, then check the result against the work-warming threshold in step 4. The arithmetic is simple. The effect on hours is not, because a colder reading can carry a work block across that threshold.

Wet skin on a job site is more common than people expect. Rain on a roof crew is the obvious case. Less obvious are sweat under layers after a hard lift, meltwater on gloves during snow clearing, spray from a pressure washer on a cold morning, and wet concrete or mortar on hands and forearms through a full shift. A crew that is soaked through is in a different situation from one that is only cold.

For the estimate, sort tasks by how wet the crew is likely to get. Work that keeps people wet and exposed to wind should use the adjusted reading. Rooftop tear-off in drizzle, a crew hosing down a slab in the open, or a snow-clearing run all fit this group. Work that keeps the crew dry and sheltered can use the unadjusted air temperature to determine WCT. Do not apply the wet-skin adjustment just because the day feels damp.

Show the adjustment as its own line in the estimate. An owner who sees "wet crew, adjusted reading" next to a block of hours can trace the extra time to a cause, which is the whole purpose of the exercise.

3. Check sustained wind above 50 km/h

Wind is where wind chill can understate the risk. The note on strong wind reads: "(In sustained winds over 50 km/h, frostbite can occur faster than indicated.)" CCOHS

The note refers to sustained wind speed, so check that figure in the forecast rather than a gust figure. Do not assign a fixed frostbite time to the work block. What the note does tell an estimator is that a reading taken in strong sustained wind may be too gentle for the work underway. The wind speed is a reason to change the plan, not only a number to write down.

For the estimate, mark affected work blocks as exposed. Then choose one or more of these responses. Move the exposed tasks, such as crane picks, open roof work, or open-deck pours, to a calmer window. Keep the crew on sheltered tasks during the strongest wind. Or apply the wet-skin adjustment from step 2 if the crew will also be wet. Each choice has an hour cost, and the estimate should state which one you priced.

Consider a roof replacement window from 1 p.m. to 4 p.m. with strong sustained wind and an exposed crew. The estimate can move the tear-off to the next calm block or keep the crew on sheltered tasks such as staging materials on the leeward side of a building. Whichever you choose, write the reason on the line, so the owner knows the wind caused the change and not the crew.

Do not wait for a forecast to confirm the plan. Wind can rise through a morning, and the crew lead is the person who will notice a gust coming across an open lot before a forecast does. Give the crew lead authority to change the schedule when conditions on site differ from the estimate, and write that authority into the job plan so the owner knows it exists.

4. Plan work-warming at -7°C and colder

This is the figure that changes labor hours most directly. The same page cites a professional suggestion for continuous outdoor work: "For example, ACGIH suggests a work-warming regimen when work is done continuously in the cold when the wind chill temperature is at or below -7°C (19.4°F)." CCOHS

The suggestion is about work done continuously in the cold. A crew that works in short bursts with real breaks between them is a different case from a crew that moves from one block to the next with no pause. The estimate should record which pattern applies to each block.

For each qualifying block, add a work-warming regimen to the labor hours. Write the assumed warm-up duration beside the hours. Base it on the crew's experience and on the regulator's guidance where you work, then write the assumption next to the line so it can be challenged and checked.

Gloves are the other half of this step. The same page addresses hand protection: "If fine manual dexterity is not required, gloves should be used below 4°C for light work and below -7°C for moderate work." CCOHS

That condition matters for estimating. Fine work such as electrical termination, finish trim, or fine tying does not fit the glove thresholds as written, so price those tasks as a separate line and note the assumption you made about hand protection. Check the protection needed for those tasks separately.

Keep one line for work-warming and one for gloves in the estimate. Then the owner can see the glove and warm-up costs separately. For related paid-time costs, see crew hours and overtime costs.

Illustrative example: price a warm-up assumption

Suppose an illustrative crew of 10 has a planned warm-up lasting 30 minutes. That adds 5 labor hours to the estimate. The duration is an illustrative estimating assumption, not a recommended break length. Put the assumed time beside the warm-up line so the owner can check the calculation and the crew lead can review the plan.

5. Schedule the four-hour extended warm break

The third figure sets the shape of the day. The guidance says: "At the end of a 4-hour period, an extended break in a warm location is recommended." CCOHS

Plan both the break and access to warmth. Choose the break length with your crew, your local rules, and the conditions on the day in mind. Record that duration as an estimating assumption.

A simple example shows the effect. A crew that starts at 7 a.m. works until 11 a.m., takes the extended warm break at the end of that four-hour period, and then returns to work. For an eight-hour block at a cold reading where the work-warming line from step 4 applies, the schedule has at least one warm break in the middle of the day, and the estimate should show it as a line item rather than hiding it in a general allowance.

Price the warm location too. A heated trailer or heated enclosure close to the work keeps travel time short. A location far from the work adds walking or driving time at every break, and that time belongs in the hours. Decide which warm location the crew will use before the bid goes out, and say so in the estimate. Review temporary heater setup rules when planning a heated space.

The break schedule is a backstop, not a replacement for watching the crew. WorkSafeBC names the warning sign to watch for: "Feeling cold is the most important warning sign to note." It also warns about the outcome of severe cold stress: "Severe cold stress can lead to hypothermia, which can be fatal." Cold stress - WorkSafeBC

Those two sentences change how the schedule should be read. If someone says they feel cold, they go to a warm location now, not at the four-hour mark. The estimate should not assume the scheduled break replaces supervision, and the crew lead should have the authority to pull people in early. Write that into the job plan, and price the supervision time that makes it real.

When you present this to an owner, describe the warm break as a planned cost, not a concession. The warm location and the travel to it are costs you can name.

6. Cover clothing, wet gear, and the crews most exposed

Clothing time is labor time, and many winter estimates leave it out. NIOSH advises: "Wear several layers of loose clothing; layering provides better insulation." Stay Safe When Working Outdoors in Cold Weather | NIOSH | CDC

Layers take time to put on at the start of each block and to take off and adjust at each break. Dry spare gloves and socks take time to swap when the first pair gets wet, and that connects back to step 2. Use the crew's experience to estimate changing time and write the assumption into the estimate. A crew that changes gear twice a day has a different hour count from one that never does.

Cold stress is not only a freezing-day problem. NIOSH also notes that trench foot can happen at temperatures as warm as 60°F. NIOSH A crew working in damp conditions above freezing still needs its footwear and socks planned. Plan dry spare socks and footwear for damp work regardless of the wind chill reading.

The page also describes who is at risk: "Anyone who has to work in a cold environment may be at risk of cold-related illnesses and injuries, or 'cold stress.' Workers who may not be able to avoid working outdoors in cold weather could include police officers, snow cleanup crews, sanitation workers, farmers, construction workers, and many others." NIOSH For an estimator, that makes cold stress a crew-wide planning item for any outdoor job. It is not an unusual case that applies only to a few specialists.

Before you finalize the hours, look at the control that removes the problem rather than the one that manages it. WorkSafeBC puts it plainly: "The most effective way to manage the risk of cold stress is to eliminate the source of exposure." WorkSafeBC For estimators, that is the option to price first. Prefabricating panels indoors, moving a pour to a heated enclosure, or shifting exposed tasks to a warmer window can shrink the warm-up and break lines you have just added. Price both the standard plan and the exposure-reduced plan, and show the owner the difference in hours and cost.

Use a record like this to connect the conditions, response and labor allowance without hiding assumptions in a flat percentage.

Next step today

Take one outdoor work block from your current estimate. Add its forecast conditions, planned warm location and assumed extra labor hours beside it. Review those assumptions with the crew lead before pricing the rest of the day.

Related guides: Heat checks: 3 costs to include in crew hours · Ladder setup: 4 figures to check before crew hours.

Questions

Can a flat winter allowance replace these lines?

A flat allowance hides the assumptions behind the added hours. Keep the conditions and planned responses visible so the owner can follow the estimate.

What should I record when the forecast changes?

Record the revised conditions and the affected work blocks. Keep the original forecast date so the change in hours remains traceable.