Heat is one of the biggest safety hazards on construction jobsites, especially during the summer months. While hydration and shade are essential, one of the most effective ways to reduce the risk of heat-related illness is by following a structured work/rest schedule.

When temperatures climb into the upper 90s and beyond, simply telling crews to "take breaks when needed" is no longer enough. Supervisors should have a plan that matches the intensity of the work being performed with the environmental conditions.

Understanding when workers should rest can help prevent heat exhaustion, heat stroke, lost productivity, and costly injuries.

What Is a Construction Work/Rest Schedule?

A work/rest schedule is a guideline that determines how much time a worker should spend performing physical labor before taking a cooling break.

The schedule considers two primary factors:

• Air temperature
• Physical workload

The more physically demanding the task, the more frequent and longer the recovery periods become as temperatures increase.

This structured approach allows workers to cool down before their bodies become dangerously overheated.

Why Heat Breaks Matter

Continuous physical activity in hot weather causes body temperature to rise faster than it can naturally cool itself.

Without adequate recovery time, workers become more susceptible to:

• Heat exhaustion
• Heat stroke
• Muscle cramps
• Fatigue
• Reduced concentration
• Poor decision making
• Increased accident risk

Regular cooling breaks help lower body temperature and allow workers to safely continue their tasks throughout the day.

Workload Makes a Big Difference

Not every construction task places the same demand on the body.

Light Work

Examples include:

• Equipment inspections
• Walking the jobsite
• Office trailer work
• Measuring or layout

Workers performing light activities generally require fewer scheduled breaks, even in hotter temperatures.

Moderate Work

Examples include:

• Installing drywall
• Carpentry
• Electrical work
• Plumbing
• Roofing prep
• Material handling

As temperatures approach triple digits, scheduled cooling periods become increasingly important.

Heavy Work

Examples include:

• Concrete work
• Demolition
• Asphalt paving
• Heavy excavation
• Carrying large materials
• Continuous shoveling

Heavy labor generates significant internal body heat, meaning work/rest schedules become critical much earlier than with lighter activities.

Example Work/Rest Recommendations

As temperatures rise, recommended work/rest cycles become more aggressive.

For example:

At 100°F

Heavy work should generally be limited to:

• 30 minutes of work
• 30 minutes of rest

At 104°F

Workers performing heavy labor should follow approximately:

• 20 minutes of work
• 40 minutes of rest

This means workers spend twice as much time cooling down as they do performing strenuous activity.

At 108°F

Moderate and heavy work enter an extremely hazardous range.

Extra precautions are necessary, including:

• Increased supervision
• Frequent hydration
• Monitoring workers for heat illness symptoms
• Considering rescheduling work
• Evaluating whether tasks should continue at all

At these temperatures, the risk of heat-related illness increases dramatically.

"Normal" Doesn't Mean Ignore the Heat

Many work/rest charts list "Normal" for lower temperature ranges.

This does not mean workers can safely work without hydration or breaks.

It simply means additional scheduled recovery periods beyond standard breaks may not yet be necessary.

Workers should still:

• Drink water frequently
• Take regular breaks
• Watch for signs of heat stress
• Communicate if they begin feeling ill

Every Jobsite Is Different

A temperature chart provides an excellent starting point, but it should never replace good judgment.

Several factors can make conditions much more dangerous than the thermometer alone suggests, including:

• High humidity
• Direct sunlight
• Lack of wind
• Heavy PPE
• Dark clothing
• Recent heat waves
• Workers who are not acclimated to the heat

Many safety professionals also use the Wet Bulb Globe Temperature (WBGT), which provides a more complete picture of environmental heat stress by accounting for humidity, radiant heat, and air movement.

Tips for Managing Heat on Construction Jobsites

A successful heat illness prevention program includes more than scheduled rest breaks.

Best practices include:

• Start demanding work earlier in the morning.
• Rotate workers performing heavy labor.
• Provide cool drinking water throughout the day.
• Encourage workers to drink before they feel thirsty.
• Set up shaded or air-conditioned recovery areas.
• Watch new employees closely as they acclimate.
• Train supervisors to recognize heat illness symptoms.
• Adjust work schedules during extreme heat events.

Build Heat Safety Into Your Daily Operations

Heat safety shouldn't rely on memory or guesswork.

Many contractors incorporate work/rest guidance into:

• Daily safety meetings
• Toolbox talks
• Morning huddles
• Job Hazard Analyses (JHAs)
• Daily logs
• Crew scheduling

Documenting these precautions also demonstrates a proactive commitment to worker safety.

Final Thoughts

Extreme heat is one of the most predictable hazards on a construction jobsite—and one of the easiest to prepare for.

Following a structured work/rest schedule helps crews stay productive while reducing the risk of heat exhaustion, heat stroke, and other heat-related illnesses.

As temperatures climb, slowing the pace of work isn't a sign of lost productivity. It's one of the smartest investments you can make in keeping your crews safe, healthy, and working throughout the summer.

By planning ahead, monitoring conditions, and giving workers adequate recovery time, contractors can reduce incidents while creating a safer, more resilient jobsite.