10.5 Signs, Signals, Barricades & Demolition (Subparts G and T)
Key Takeaways
- Danger signs use red as the predominating color on the upper panel and are used only where an immediate hazard exists; caution signs are predominantly yellow and warn against potential hazards or unsafe practices.
- Accident prevention tags are a temporary means of warning employees of an existing hazard and may never substitute for an accident prevention sign.
- Before demolition begins, a competent person must perform an engineering survey of the structure and adjacent structures, and the employer must have written evidence that the survey was performed.
- All electric, gas, water, steam, sewer, and other service lines must be shut off, capped, or otherwise controlled outside the building line before demolition work starts, with the utility notified in advance.
- Material dropped more than 20 feet outside the exterior walls requires an enclosed chute; wall openings that expose a fall hazard must be protected to a height of approximately 42 inches.
10.5 Signs, Signals, Barricades & Demolition (Subparts G and T)
Core Principle: Subpart G (1926.200–203) is how a jobsite tells people what it is about to do to them. Subpart T (1926.850–860) governs demolition, the one phase of construction in which the structure's real condition is unknown, its as-built drawings are often wrong, and the sequence of removal determines whether the building comes down where it was planned to. Signs, signals, and barricades is part of the named outreach elective "Motor Vehicles; Mechanized Equipment and Marine Operations; Rollover Protective Structures and Overhead Protection; and Signs, Signals, and Barricades."
1. Accident Prevention Signs and Tags (1926.200)
The General Rule
Signs and symbols required by Subpart G shall be visible at all times when work is being performed, and shall be removed or covered promptly when the hazards no longer exist. That second half matters: a site papered with stale danger signs teaches workers to ignore them.
Sign Types, Uses, and Colors
| Sign Type | When It Is Used | Color Scheme |
|---|---|---|
| Danger (1926.200(b)) | Only where an immediate hazard exists | Red as the predominating color for the upper panel; black outline on the borders; a white lower panel for additional wording |
| Caution (1926.200(c)) | Only to warn against potential hazards or to caution against unsafe practices | Yellow as the predominating color; black upper panel and borders; yellow lettering of "caution" on the black panel; lower yellow panel for additional wording in black letters |
| Exit (1926.200(d)) | Marking exits where required | Legible red letters not less than 6 inches high on a white field, principal stroke of the letters at least three-fourths inch wide |
| Safety instruction (1926.200(e)) | General instructions and suggestions relative to safety measures | White with a green upper panel with white letters for the principal message; additional wording in black on the white background |
| Directional (1926.200(f)) | Directing traffic other than automotive traffic | White with a black panel and a white directional symbol; additional wording in black on white |
| Traffic control (1926.200(g)) | Points of hazard in construction areas | Design and use of all traffic control devices, including signs, signals, markings, barricades and other devices for protection of construction workers, shall conform to Part 6 of the MUTCD |
Danger and caution signs follow the specifications illustrated in ANSI Z35.1-1968 or ANSI Z535.2-2011, incorporated by reference in 1926.6 — either edition is acceptable, which is why both the older red-oval and the modern Z535 formats are seen in the field.
Accident Prevention Tags (1926.200(h))
Tags are a temporary means of warning employees of an existing hazard, such as defective tools or equipment. The key sentence is the limitation: they shall not be used in place of, or as a substitute for, accident prevention signs. A "Danger — Do Not Operate" tag on a broken saw is correct use; a tag hung where a permanent danger sign is required is not.
Signaling and Barricades (1926.201 and 1926.202)
- 1926.201(a) Flagging: signaling by flaggers and the use of flaggers, including the warning garments worn by flaggers, shall conform to Part 6 of the MUTCD.
- 1926.201(b) Crane and hoist signals: where employees are exposed, signals shall be posted at the operator's station.
- 1926.202 Barricades: barricades for protection of employees shall conform to Part 6 of the MUTCD.
2. Demolition: Preparatory Operations (1926.850)
Subpart T front-loads its safety into work that happens before a single wall comes down.
The Engineering Survey — 1926.850(a)
Prior to permitting employees to start demolition operations, an engineering survey shall be made, by a competent person, of the structure to determine the condition of the framing, floors, and walls, and possibility of unplanned collapse of any portion of the structure. Any adjacent structure where employees may be exposed shall also be similarly checked. The employer shall have in writing evidence that such a survey has been performed.
Three examinable points hide in that sentence: the survey is performed by a competent person (not necessarily an engineer despite the name); it must cover adjacent structures where employees may be exposed; and the employer must hold written evidence that it was done.
Fire, Flood, and Explosion Damage — 1926.850(b)
Where employees must work within a structure damaged by fire, flood, explosion, or other cause, the walls or floor shall be shored or braced.
Utilities — 1926.850(c) and (d)
All electric, gas, water, steam, sewer, and other service lines shall be shut off, capped, or otherwise controlled, outside the building line before demolition work is started. In each case, any utility company which is involved shall be notified in advance. If a utility must be maintained during demolition, it shall be temporarily relocated as necessary and protected.
Hazardous Substances — 1926.850(e)
It must be determined whether any hazardous chemicals, gases, explosives, flammable materials, or similarly dangerous substances have been used in any pipes, tanks, or other equipment on the property. Where their presence is apparent or suspected, testing and purging shall be performed and the hazard eliminated before demolition is started.
Physical Preparations — 1926.850(f) through (j)
| Paragraph | Requirement |
|---|---|
| (f) | Where a hazard exists from fragmentation of glass, such hazards shall be removed |
| (g) | Where a hazard exists to employees falling through wall openings, the opening shall be protected to a height of approximately 42 inches |
| (h) | When debris is dropped through holes in the floor without chutes, the landing area shall 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; signs warning of falling materials at each level; no removal below until debris handling ceases above |
| (i) | All floor openings not used as material drops shall be covered with material substantial enough to support the imposed load, properly secured against accidental movement |
| (j) | Except for the cutting of holes for chutes, holes for equipment, and similar necessary openings, floor openings within 10 feet of any wall being demolished shall be planked solid |
Stairs, Passageways, and Ladders — 1926.851
Only stairways, passageways, and ladders designated as means of access to the structure of a building shall be used, and other access ways shall be entirely closed at all times. All stairs, passageways, ladders, and incidental equipment covered by the section shall be periodically inspected and maintained in a clean, safe condition. In a multistory building where a stairwell is being used, it shall be properly illuminated by either natural or artificial means and completely and substantially covered over at a point not less than two floors below the floor on which work is being performed, with access to the floor where work is in progress through a properly lighted, protected, and separate passageway.
Chutes — 1926.852
- (a) No material shall be dropped to any point lying outside the exterior walls of the structure unless the area is effectively protected.
- (b) All material chutes, or sections thereof, at an angle of more than 45° from the horizontal, shall be entirely enclosed, except for openings equipped with closures at or about floor level for the insertion of materials. Those openings shall not exceed 48 inches in height measured along the wall of the chute, and at all stories below the top floor such openings shall be kept closed when not in use.
- (c) A substantial gate shall be installed in each chute at or near the discharge end, with a competent employee assigned to control its operation and the backing and loading of trucks.
- (f) Where the material is dumped from mechanical equipment or wheelbarrows, a securely attached toeboard or bumper, not less than 4 inches thick and 6 inches high, shall be provided at each chute opening. Any space between the chute and the edge of the floor openings through which it passes shall be solidly covered over.
- (g) Chutes shall be designed and constructed of such strength as to eliminate failure due to impact of materials or debris loaded therein.
3. Sequence and Mechanical Demolition
- 1926.854 Walls, masonry sections, and chimneys: masonry walls or sections of masonry shall not be permitted to fall upon the floors of the building in such masses as to exceed the safe carrying capacities of the floors. No wall section more than one story in height shall be permitted to stand alone without lateral bracing, unless the wall was originally designed to stand without such support and is in a safe condition. Employees shall not be permitted to work on the top of a wall when weather conditions constitute a hazard.
- 1926.856 Removal of walls, floors, and material with equipment: floor openings shall have curbs or stop-logs to prevent equipment from running over the edge, and mechanical equipment shall not be used on floors or working surfaces unless those surfaces are of sufficient strength to support the imposed load.
- 1926.859 Mechanical demolition: no employee shall be permitted in any area that can be adversely affected by demolition when balling or clamming is being performed; the weight of the demolition ball shall not exceed 50 percent of the crane's rated load, based on the length of the boom and the maximum angle of operation at which the ball will be used, or 25 percent of the nominal breaking strength of the line by which it is suspended, whichever results in a lesser value. The crane boom and load line shall be as short as possible, and the ball shall be attached to the load line with a swivel-type connection to prevent twisting, and attached by a positive means so it cannot become accidentally disconnected.
4. Demolition and the Rest of 1926
Demolition never stands alone. On a live demolition project a trainer should expect all of the following to apply simultaneously:
| Hazard | Governing standard |
|---|---|
| Falls at 6 ft or more, holes, and wall openings | Subpart M, plus 1926.850(g)-(j) |
| Asbestos in thermal system insulation, flooring, and surfacing | 1926.1101, including the Class I through IV work classifications |
| Lead in paint on structural steel and plaster | 1926.62 trigger tasks, including manual demolition of lead-containing structures |
| Silica from concrete cutting, crushing, and jackhammering | 1926.1153 Table 1 |
| Cranes and the demolition ball | Subpart CC and 1926.859 |
| Struck-by from equipment and falling material | Subpart O, 1926.252, 1926.850(h) |
| Confined spaces in tanks, vaults, and pits | Subpart AA |
A site superintendent posts a yellow sign reading 'CAUTION - ENERGIZED 480V PANEL - ARC FLASH HAZARD' on the door of a live switchgear room. What is wrong under 29 CFR 1926.200?
A contractor is about to begin demolishing a two-story commercial building and an adjacent party wall is shared with an occupied store. Under 29 CFR 1926.850(a), what must happen before employees start demolition operations?
A demolition crew is removing plaster and lath and wants to drop the debris from the third floor into a dumpster positioned outside the building, a drop of about 35 feet. What does Subpart T require?