Safe Solutions

Ladder-jack scaffolds

Roofing contractors use ladder-jack scaffolds for various types of work, including gutter and metal coping installations, soffit and fascia details, mansard roof installations and siding applications. Occupational Safety and Health Administration (OSHA) rules related to setup and use of ladder-jack scaffolds are found in "Subpart L—Scaffolds" of OSHA's construction regulations and contain specific requirements for roofing contractors that apply to all ladder-jack scaffold setups without regard for the task at hand.

A ladder-jack scaffold simply is a platform or plank suspended on supports, or jacks, which are attached to the rungs of two or more ladders. The ladders are set at intervals apart from each other to accommodate the length of the platform or plank and provide intermediate support if required. A worker then can perform tasks along a portion of a building's edge by working off the plank instead of making multiple moves with a single ladder.


OSHA requires the platform or plank portion of a ladder-jack scaffold to be at least 12 inches wide. Ordinarily, aluminum scaffold planks—either fixed-length or extension-type—are used with ladder jacks because of aluminum scaffold planks' light weight and load capacity. Planks available from major scaffold equipment manufacturers generally are designed to comply with OSHA's 12-inch width requirement, and some models are 14 inches wide. They also should have a posted load rating in pounds that—in the case of fixed planks—may allow two workers to be on a plank at the same time.

Although the most common fall-protection threshold height in construction is 6 feet, the scaffold regulation requires fall protection for any worker more than 10 feet above a lower level. The regulation states the only option for fall protection on a ladder-jack scaffold is a personal fall-arrest system, usually consisting of a harness, lanyard, lifeline and anchorage capable of supporting 5,000 pounds.

The practical difficulty most often encountered is securing the anchor at a point above a roofing worker that can meet the load requirement. For residential applications, a strap-type, D-ring anchor installed at a roof's ridge or in a rafter close to a roof's eave would be suitable. Commercial applications without permanent anchors in place may require a designed solution or temporary anchor that can be removed and patched.

One of the more obscure provisions relating to ladder-jack scaffold use is the maximum platform height restriction. OSHA regulations state the platform height—the top of the plank on which a roofing worker stands—may not exceed 20 feet from the ground. So even though workers may work from 36- or 40-foot extension ladders, no ladder-jack platform may be used above 20 feet from the ground or a lower level.

Ladder-jack scaffolds also are subject to clearance requirements relating to electrical power lines. OSHA provides that scaffolds may not be erected or used closer than 10 feet to uninsulated energized power lines of 50 kilovolts (kV) or less. If a power line exceeds 50 kV, that distance must be increased by 4 inches for every additional 10 kV. This calculation depends on knowing the nature of the lines that are near where a worker may be working. Most residential service power lines usually will require the 10-foot clearance. The OSHA regulation also sets lesser clearance distances for insulated power lines, but it is prudent to use the uninsulated power line requirements because those lines represent a vast majority of electrical distribution lines encountered in roofing.

The setup and use requirements for ladders under OSHA regulations also must be considered when using ladder-jack scaffolds. The regulation's most critical provision states ladders may not be loaded beyond the manufacturer's rated capacity or the maximum intended load for which it was built. This can be a problem if two workers occupy a platform or if tools and materials are on the platform, as well. Workers must be made aware of the limitations of the platform and ladders and trained in proper use and setup of the ladders and scaffold to avoid exceeding load limitations.


Ladder-jack scaffolds can be an effective means of accessing a variety of exterior building elements, but you must be vigilant when conveying to workers the proper manner to set up the scaffolds, limitations of the equipment and fall protection required by OSHA.

Harry Dietz is NRCA's director of safety and regulatory compliance.


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