The Fire Watch and Post-Work Monitoring

You need a fire watch whenever hot work is done where more than a minor fire could develop, including any of these:

• Combustible material is closer than 35 feet to the point of the work.
• Combustibles are more than 35 feet away but easily ignited by sparks.
• Wall or floor openings within 35 feet expose combustibles in adjacent areas, including concealed spaces in walls or floors.
• Combustible materials are against the opposite side of metal walls, partitions, ceilings, or roofs and could ignite from conduction or radiation.

When those conditions aren't present and the area is genuinely clear, a dedicated watcher may not be required — but that's a judgment the permit and supervisor make, not the person holding the torch.

The fire watch has one job and shouldn't be pulled onto anything else while hot work is live. That person:

• Watches the work area and the surrounding spaces — including levels below and the far side of walls — for sparks and smoldering.
• Has firefighting equipment right at hand and knows how to use it.
• Puts out small fires within the extinguisher's capacity and sounds the alarm for anything bigger.
• Knows how to raise the alarm and get help fast.

A fire watch who's also welding, spotting a crane, or running for parts isn't a fire watch.

Here's the part crews skip: the fire watch is maintained for at least 30 minutes after hot work is completed, to detect and extinguish smoldering fires. Sparks that landed in insulation, dust, or a wall cavity can smolder for a long time before they break into open flame.

So the work isn't done when the torch shuts off. Someone keeps eyes on the area — and the concealed spaces sparks could have reached — for a full half hour. Some jobs and permits require longer. Don't clear the fire watch early because the visible work looks finished.