What drives smoke spread in a large building

Ceiling height
Smoke rises to the roof and spreads outward under it before settling, so distance from the fire matters less than height.
Air handling
Rooftop units, make-up air and exhaust fans can carry smoke into offices and other zones if they ran during the fire.
Openings
Overhead doors, unsealed wall penetrations and open stairwells let smoke into mezzanines and adjoining spaces.
Fuel
Plastics, packaging and rubber produce heavier, oilier residue than wood or paper.
Duration
A smoldering fire that goes unnoticed for some time can spread more residue than a brief, hot flare-up.

Mapping the affected area

Before scope is written, walk the building from the fire area outward with the restoration provider and, ideally, the adjuster. Look at horizontal surfaces at different heights: tops of racking, light fixtures, beams, window sills and the tops of machinery. Wipe a white cloth or a dry sponge across each and photograph the result with a label showing where it was taken. A grid of these wipes turns a vague argument about how far the smoke went into a record everyone can see.

Pay attention to places that were closed off during the fire. An office with its door shut may be clean, or it may have pulled smoke through the return air plenum above the ceiling. Electrical rooms, server closets and break rooms deserve their own check because residue there affects sensitive equipment and food areas.

The heating and ventilation system needs a separate look. If units were running, filters will be loaded with residue and ductwork may need cleaning before the system runs again. Running a contaminated system to clear the air can redistribute residue into areas that were clean.

Two ways to set the cleaning boundary

Restoration providers and adjusters sometimes disagree about how much of a building is in scope. Each approach has trade-offs.

Zone by evidence

  • Scope follows wipe tests, photos and visible residue
  • Can reduce cost and disruption in large buildings
  • Needs careful documentation to defend the boundary
  • Risk of missing light residue or odor in edge areas
  • Areas outside the boundary may need retesting later

Clean the whole volume

  • Treats the open bay as one air space
  • Simpler to explain and verify afterward
  • Larger scope, longer shutdown of more of the floor
  • May be favored when HVAC carried smoke widely
  • Can be hard to justify for a small, brief fire

Before the cleaning boundary is agreed

Use this list during the walk-through.

  • Wipe samples photographed and labeled at several heights and distances from the fire.
  • HVAC units identified as running or off during the fire, with filters inspected.
  • Offices, electrical rooms and break rooms checked separately, including above the ceiling.
  • Doors, penetrations and stairwells noted where smoke could pass between spaces.
  • Product and packaging in the boundary listed for inspection or disposal decisions.
  • Odor noted room by room, even where no residue is visible.
  • Boundary drawn on a floor plan and shared with the adjuster in writing.

Common questions

Can operations continue in parts of the building that look clean?

Often, once the boundary is agreed and work zones are separated with containment. Ask the provider how they will keep residue from being tracked or blown into the operating areas.

Do rooftop units need to stay off?

Ask the provider and your mechanical contractor. Running a unit with contaminated filters or ducts can spread residue, but some spaces need ventilation or heat for safety and drying.

General information for Commerce City, not a quote or professional advice. In an emergency, call 911.