Demolition engineering survey and utility isolation

Survey before workers start demolition

Demolition changes the load path as walls, floors, roofs, and connections are removed. A structure that appears stable may depend on a wall or frame that the demolition sequence will weaken. OSHA therefore requires an engineering survey before employees begin demolition. A competent person evaluates the condition of the framing, floors, and walls, the possibility of an unplanned collapse, and any adjacent structure where workers may be exposed. The employer must have written evidence that the survey was performed.

The survey is a planning tool, not a paperwork formality. It should identify the construction type, additions and alterations, damaged areas, load-bearing elements, unusual framing, and the sequence that keeps the remaining structure stable. The competent person must understand the structure well enough to identify hazards and recommend controls. If the survey reveals conditions requiring engineering analysis or shoring design beyond that person’s qualifications, bring in a registered professional engineer.

Check neighboring structures and the work zone

The survey also considers an adjacent structure where employees may be exposed. Demolition vibration, excavation, falling debris, or loss of lateral support can affect a neighboring wall or sidewalk. Check party walls, shared foundations, canopies, utility connections, and occupied spaces near the work. Establish exclusion zones and sidewalk protection where needed, and coordinate with property owners and authorities before the crew starts removing material.

If the building was damaged by fire, flood, explosion, or another cause and workers must enter it, OSHA requires walls or floors to be shored or braced. Do not rely on the fact that the building remained standing before the job. A damaged structure may have hidden loss of capacity. The survey should guide access, shoring, bracing, sequence, and whether any portion must be demolished remotely.

Control utilities outside the building line

Before demolition begins, electric, gas, water, steam, sewer, and other service lines must be shut off, capped, or otherwise controlled outside the building line. The utility company involved must be notified in advance. If a service must remain active, the line is temporarily relocated as necessary and protected. This rule prevents a crew from cutting into energized wires, gas, pressurized water, or sewer lines while structure is being removed.

Confirm each utility’s owner, location, isolation point, and status; do not assume a meter removal means the entire service is safe. Obtain written confirmation or a tag where the utility or project procedure requires it. Mark any active temporary service that remains and protect it from demolition equipment. Coordinate lockout/tagout, permit-to-work, and utility procedures, but remember that building utility isolation and employee-equipment LOTO address overlapping but different systems.

Investigate hazardous contents

The preparatory operation also determines whether hazardous chemicals, gases, explosives, flammable materials, or similarly dangerous substances were used in pipes, tanks, or other equipment on the property. If such materials are apparent or suspected, testing and purging must eliminate the hazard before demolition. Pipes that look empty may contain residual liquid or vapor. A qualified hazardous-materials contractor may need to identify and abate asbestos, lead, or other regulated materials under separate requirements before structural demolition.

Remove glass where fragmentation creates a hazard and protect employees from falls through wall openings as the demolition proceeds. A pre-demolition survey should connect the building condition to these specific exposures. The crew needs a sequence for removing glazing, protecting openings, and clearing falling debris. If site conditions differ from the survey, stop and reassess rather than continuing under a plan that assumed a different structure.

Example: a renovated commercial building

A contractor plans to remove the interior of a commercial building while preserving the façade. The survey identifies the façade’s bracing, floor diaphragm connections, a previous structural opening, and an occupied neighboring building. The team stages temporary bracing, sets an exclusion zone, confirms utility isolation at the service points outside the building line, and marks a protected fire line that must remain active. The written survey and demolition sequence are reviewed before tools enter the structure.

During work, the crew discovers an unrecorded steel post embedded in a wall. It may carry floor load. They pause demolition, secure the area, and have the competent person and engineer evaluate the condition. The survey is updated and the sequence revised. Continuing to cut around an unknown support could trigger an unplanned collapse even if earlier survey paperwork was complete.

Common mistakes and exam cues

Common misses include beginning demolition before a written survey, checking only the target building and not adjacent exposed structures, relying on meter removal without controlling services beyond the building line, and failing to investigate pipes or tanks with hazardous contents. Another error is treating the survey as static after unexpected framing appears. OSHA’s key preparation concepts are structure, utilities, hazardous contents, glass and openings, and adjacent exposure.

For exam questions, remember the timing: before employees start demolition. Identify who performs the survey, what it evaluates, and that written evidence is required. Then distinguish service lines that are shut off/capped/controlled from those intentionally maintained and relocated/protected. A competent person survey does not replace the need for specialized engineering or hazardous-material controls where the condition calls for them.

Quick review

• Before demolition, a competent person surveys framing, floors, walls, collapse potential, and exposed adjacent structures.
• Keep written evidence that the survey was performed.
• Shut off, cap, or otherwise control service lines outside the building line; notify utilities.
• Relocate and protect utilities that must remain in service.
• Test and purge hazardous contents when apparent or suspected; reassess when field conditions change.