Demolition Safety

The engineering survey and damaged structures

No one starts until the survey is done

Before employees are allowed to start demolition, a competent person must make an engineering survey of the structure. It checks the condition of the framing, floors and walls, and the possibility of unplanned collapse of any part of it.

• Any adjacent structure where employees may be exposed must be checked the same way.
• The employer must have written evidence that the survey was done.

Damaged buildings

When employees are required to work inside a structure damaged by fire, flood, explosion or other cause, the walls or floor must be shored or braced.

Reference: 29 CFR 1926.850(a) · 29 CFR 1926.850(b)

Utilities and hidden hazards

Service lines

Before demolition work starts, all electric, gas, water, steam, sewer and other service lines must be shut off, capped, or otherwise controlled, outside the building line. Any utility company involved must be notified in advance.

If power, water or other utilities must stay on during demolition, those lines must be temporarily relocated as necessary and protected.

What was in the pipes and tanks?

It must be determined whether hazardous chemicals, gases, explosives, flammable materials or similar dangerous substances were used in any pipes, tanks or other equipment on the property. When they are apparent or suspected, testing and purging must be done and the hazard eliminated before demolition is started.

Glass

Where a hazard exists from fragmenting glass, that hazard must be removed.

Reference: 29 CFR 1926.850(c) · 29 CFR 1926.850(d) · 29 CFR 1926.850(e) · 29 CFR 1926.850(f)

Getting in, and holes in walls and floors

Access

• Employee entrances to multi-story structures must be completely protected by sidewalk sheds or canopies, covering at least 8 feet out from the face of the building. All such canopies must be at least 2 feet wider than the building entrances or openings (1 foot wider on each side) and able to sustain a load of 150 pounds per square foot.
• Use only the stairways, passageways and ladders designated as access. Other access ways stay entirely closed at all times.

Wall openings

Where you could fall through a wall opening, it must be protected to a height of approximately 42 inches.

Dropping debris through floor holes without a chute

• The landing area must be completely enclosed with barricades not less than 42 inches high and not less than 6 feet back from the projected edge of the opening above.
• Warning signs for falling materials go up at each level.
• No removal from the lower area until debris handling ceases above.

Other floor openings

• Openings not used as material drops must be covered with material strong enough for any load that may be imposed, and secured so it cannot move by accident.
• Floor openings within 10 feet of any wall being demolished must be planked solid, except when employees are kept out of the area below.

Reference: 29 CFR 1926.850(k) · 29 CFR 1926.851(a) · 29 CFR 1926.850(g) · 29 CFR 1926.850(h) · 29 CFR 1926.850(i) · 29 CFR 1926.854(e)

Parts of a safe debris chute

Material may not be dropped outside the exterior walls of the structure unless that area is effectively protected. A chute is the usual way.

Guardrail

Any chute opening where workers dump debris needs a substantial guardrail approximately 42 inches above the surface they stand on.

Toeboard or bumper

Where material is dumped from mechanical equipment or wheelbarrows, each chute opening needs a securely attached toeboard or bumper not less than 4 inches thick and 6 inches high.

Openings and closures

A chute at more than 45° from horizontal is entirely enclosed except for openings with closures at or about floor level. Openings are no more than 48 inches high along the chute wall, and below the top floor they stay closed when not in use.

Discharge gate

Each chute has a substantial gate at or near the discharge end. A competent employee is assigned to control the gate and the backing and loading of trucks.

Discharge area

When operations are not in progress, the area around the discharge end must be securely closed off.

Reference: 29 CFR 1926.852(a) · 29 CFR 1926.852(b) · 29 CFR 1926.852(c) · 29 CFR 1926.852(d) · 29 CFR 1926.852(e) · 29 CFR 1926.852(f)

Top down, one story at a time

Work from the top down

Exterior walls and floors come down starting at the top and moving downward. Each story is removed and dropped into the storage space before removal starts on the story below. The exception is preparatory work, such as cutting holes for chutes or drops and preparing storage space.

Leave the supports alone

Structural or load-supporting members on a floor are not cut or removed until all stories above have been demolished and removed. Cutting floor beams to dispose of materials or install equipment is still allowed when the rules for floor openings and manual floor removal are met.

Walls

• A wall section more than one story high may not stand alone without lateral bracing, unless it was designed and built to stand on its own and is in safe enough condition to support itself.
• All walls are left stable at the end of each shift.
• No one works on top of a wall when weather makes it hazardous.
• Masonry may not fall onto floors in masses that exceed what the floors can safely carry.

Reference: 29 CFR 1926.850(j) · 29 CFR 1926.854(d) · 29 CFR 1926.854(b) · 29 CFR 1926.854(c) · 29 CFR 1926.854(a)

Floors, storage and equipment loads

• Openings cut in a floor for disposing of materials may be no larger than 25 percent of the aggregate total floor area, unless the lateral supports of the removed flooring remain in place.
• Floors weakened by demolition must be shored to safely carry the load the demolition will put on them.
• Waste and debris stored on any floor may not exceed the allowable floor loads.
• Mechanical equipment is not used on a floor or working surface unless it is of sufficient strength to support the load.
• Floor openings need curbs or stop-logs so equipment cannot run over the edge.

Reference: 29 CFR 1926.853 · 29 CFR 1926.857(a) · 29 CFR 1926.856(a) · 29 CFR 1926.856(b)

Balling, clamming and pulling walls

Stay out of the zone

When balling or clamming is being done, no workers are allowed in any area that can be adversely affected. At other times, only the workers needed for the operation are allowed in that area.

The demolition ball

• Its weight may not exceed 50 percent of the crane's rated load (based on boom length and the maximum angle it will be used at), or 25 percent of the nominal breaking strength of the line it hangs from, whichever is less.
• The crane boom and loadline are kept as short as possible.
• The ball is attached with a swivel-type connection and by positive means so it cannot come loose by accident.

Pulling walls over

• All affected steel members are cut free first.
• Roof cornices and other ornamental stonework are removed first.

Reference: 29 CFR 1926.859(a) · 29 CFR 1926.859(b) · 29 CFR 1926.859(c) · 29 CFR 1926.859(d) · 29 CFR 1926.859(e) · 29 CFR 1926.859(f)

Inspections continue as the work goes on

The first survey is not the last look. During demolition, a competent person makes continuing inspections as the work progresses, looking for hazards from weakened or deteriorated floors or walls, or loosened material.

Workers: if a floor sags, a wall cracks or material is hanging loose, stop and tell the competent person.

Reference: 29 CFR 1926.859(g)