Few things are more common on construction sites than scaffolds made of steel tubing and lumber planking. However familiar, by definition scaffolds are temporary structures, used to put men and materials on elevated platforms to perform work. If not properly designed, erected, inspected and maintained — or if used by workers insufficiently trained or not employing fall protection — scaffolds are accidents getting ready to happen.
While most larger projects use modular “tube and coupler” scaffolding, supplied and erected by specialized subcontractors, small projects, especially residential repairs done by non-union contractors, are notorious for accidents due to poor scaffolding practices. Scaffold safety isn’t “rocket science,” but many details require careful attention. And, while proper design and erection are obviously critical, frequent inspections, maintenance, employee training, and work rule enforcement are also essential.
There are many kinds of scaffolds. In addition to tubular-frame scaffolds, the varieties mentioned in OSHA § 1910.28 include (among others) mason’s and stone setters’ adjustable multiple-point suspension scaffolds, “boatswains’ chairs,” bricklayers’ square scaffolds, carpenters’ bracket scaffolds, needle-beam scaffolds, plasterers’, decorators, and large-area scaffolds, roofing brackets, and window-jack scaffolds. Many of these have specialized applications, or are restricted to light-duty or limited height applications.
Once a mainstay but now outmoded and rare, are wood-pole scaffolds. General-purpose scaffolds of this type, once common, are now seldom seen, as they must be built “from scratch,” and cannot readily be moved.
Design and erection fundamentals for scaffolds begin with the necessity to have a safety rating of at least four, and placement on a firm, level surface. Scaffold legs must be set on plain or adjustable bases, placed on mud sills or other foundations adequate to support the maximum intended load. If you can’t avoid placing the base plates on soft ground, use plywood pads (minimum 24” square) beneath them. Any scaffold must be designed by a competent person. A tube scaffold, more than 125 feet in height above the base plates, must have written drawings and specs, designed by a professional engineer.
Frames must be placed one on top of the other with coupling or stacking pins, to provide proper vertical alignment of the legs. Scaffolds must be braced by cross-bracing or diagonal braces, or both, of such length as will automatically square and align vertical members, so that the erected scaffold remains plumb, square, and rigid. Planks and walk boards must be a minimum of 36” below the stop of the scaffolding. All planking must be of “Scaffold Grade;” the maximum permissible span for 1-1/4” x 9” or wider plank of full thickness is 4’, with medium loading of 50 psf. Planking or platforms must be overlapped a minimum of 12”, or secured from movement. They should extend over their end supports not less than 6”, or more than 18”.
No part of the scaffold should be located within 10 feet of energized power lines. All platforms must be provided with 2” x 4” guardrails, at a height of between 36” and 42.” Unless the area below is barricaded off, or the scaffold will not have open sides more than 10’ high, it must also have toeboards, not less than 4” in height. If anyone will be required to work or pass under the scaffold, it must be provided with a ½” wire-mesh screen, covering the entire opening between the toeboard and the guardrail. Overhead protection must be provided on a scaffold exposed to overhead hazards.
Where the height of a scaffold is to exceed 20’, outriggers must be used to enlarge the base, and the scaffold must be tied into the building if feasible. The scaffold should be affixed to the building at intervals of not more than 30’ horizontally, and 26’ vertically. Where scaffolds are to be suspended using wire or fiber rope, the same must be capable of supporting at least six times the intended load. Only treated fiber rope should be used for or near work involving the use of corrosive substances or chemicals, and only wire rope-supported scaffolds used for cleaning buildings over 50’ in height with acid solutions. Special precautions should be taken to protect scaffold members, including wire or fiber ropes, when using a heat-producing process.
The most fundamental day-to-day safety rules in using scaffolds include the following. First, no one should be permitted to go up on a scaffold who is untrained in safe practices. Training should be repeated from time to time, and written records of topics covered, and the names of attendees, maintained. If work conditions, or the type or use of scaffolding changes, the training must be updated, and provided anew.
The scaffold should be checked before each work shift (and every time before use after it has been modified or moved) by a “competent person.” Everyone using the scaffold should be instructed to report signs of cracks, loose fasteners or bolts, or indications that the scaffold is out of plumb, or that vertical and horizontal members are not perpendicular.
Wheels must be locked before anyone climbs on the scaffold. The scaffold must never be moved with anyone on it. Safe access (normally, fixed ladders or ramps) must be provided, especially where the work requires a gap of 2 feet or more between the work area and the scaffold. Adjustable legs, intended for use in leveling the scaffold, must not be used to stretch the platform height. Where additional height is required, add one or more scaffold sections. Leveling should not be performed while anyone is on the scaffold.
Persons working on the scaffold must keep their center of gravity above the scaffolding. Employees must be forbidden to push/pull or lean against the wall or ceiling when standing or sitting on a scaffold, unless it is securely tied into the building. Employees must not climb or stand on diagonal braces, and should work only while standing on one of the platforms. No one shall work below or in the fall zone of the scaffolding. Portable ladders must not be leaned against the scaffold, or used on a scaffold platform. If there is a storm or heavy winds, a worker must not climb on the scaffolding unless he is using fall protection or a wind screen. Workers should not go onto the scaffold with snow or ice on it, except to remove the same, and to apply sand to the planking to prevent slipping when work resumes in clear conditions.
Open sides of the scaffold must be equipped with guardrails. Platforms must be kept clear of clutter, to prevent trips and falls. Last but not least, all workers on scaffolds working or walking at a height of 10’ or greater must have adequate fall protection in the form of a harness, and must tie off religiously. Since falls are the #1 cause of preventable construction fatalities, supervisors must be instructed to remind workers of the foregoing rules regularly, to call out violations, and to enforce the rules with a graduated system of disciplinary penalties. I am reminded of an incident in Brooklyn a couple of years ago, in which a scaffold collapsed beneath three men working five stories above grade. All three men had been provided with harnesses. The two men who were tied off got a bad scare, and spent 20 minutes dangling, until they were rescued by firefighters. The third man, who was not tied off, fell to his death. Safety rules are useless in preventing accidents — and OSHA citations — unless they are enforced. No one seen working aloft without his lanyard fastened should ever escape being spoken to, at least.
Needless to say, any scaffold seen to be damaged or improperly erected should not be used until repaired or corrected.
The foregoing covers most of the basics, but be sure to consult the OSHA regs if you plan to use a wood-pole or “specialty” scaffold. And, while most scaffolding subs are knowledgeable and conscientious, remember that, ultimately, if your employees will use the scaffold, or you’re the general contractor, it’s your responsibility.Thomas H. Welby is a licensed professional engineer, as well as an attorney and managing partner of Welby, Brady & Greenblatt, LLP, a construction law firm with its main office in White Plains. Geoffrey S. Pope, counsel to the firm, assists in the preparation of this series. Articles in this series are for general guidance only, and should not be relied upon as providing all information necessary for compliance with OSHA and other legal requirements.
Thomas H. Welby is a licensed professional engineer, as well as an attorney and managing partner at Welby, Brady & Greenblatt, LLP, a construction law firm with its main office in White Plains. Geoffrey S. Pope, counsel to the firm, collaborates in the preparation of this series. Articles in this series are for general guidance only, and should not be relied upon as providing all information necessary for compliance with OSHA and other legal requirements.