Solution Summary: Demolition Bars
A demolition bar is an engineering control that may help reduce stooped or kneeling postures, and minimize stressful hand and wrist activity. A demolition bar is wedged between the material being removed (roofing, decking, or subfloor) and the foundation. Once in place, the handle is pushed downward, providing an upward force to pry the object out of the foundation.
A demolition bar consists of a handle connected to lift plate. Lift plates are flat steel that is angled so that it can be wedged underneath material (Figure 1). Handle length ranges from 40-60 in and are either steel or lightweight fiberglass depending on the make and model.
Figure 1. The Gutster Demo-Bar
To operate, the lift plate is wedged between the material being removed (roofing, decking, or subfloor) and the foundation. Once in place, the handle is pushed downward which provides an upward force and prys the material off of the foundation (Figure 2). These steps are repeated until the material is completely removed.
Figure 2. The Duckbill Deck Wrecker
Stooped or kneeling posture and stressful hand and wrist activity can lead to numerous musculoskeletal disorders (MSDs). The low back discs can be injured when excessive loads are placed on the spine. Overworking back muscles can also result in strains. Shoulder and wrist tendonitis may occur with repetitive twisting, lifting, or pulling. Tendonitis is caused from overuse and is inflammation of a tendon that results in pain. A demolition bar reduces the risks of MSDs associated stressful hand and wrist activity and stooped postures because they eliminate hammering and can be operated from an upright position.
How Risks are Reduced:
A demolition bar minimizes the time spent kneeling and stooping while prying up material. Once the bar is in place, the tool can be operated from a standing position. Additionally, a demolition bar eliminates hammering pry bar, which is common in traditional roofing, decking, and subfloor removal. Instead, a downward force on the handle from a standing position is sufficient to pull out the roofing, decking, and/or subfloor.
There is ample evidence that low back disorders are associated with stooping and kneeling (Bernard, 1997; Spielholz, 2006). Research has shown that workers who spend more time in stooped posture or other awkward back postures are at a higher risk for developing low back problems (Bernard, 1997). Studies have reported a decrease in low back pain and stress if materials are handled at or near waist height (Hoogendoorn et al., 2000). Additionally, research has shown that forceful elbow and/or hand and wrist movements (e.g. hammering) increased the likelihood of tendinitis in the associated joint and/or carpal tunnel syndrome (Bernard, 1997).
Safety and health experts, as well as the manufacturer, believe that a demolition bar requires less demand on the worker because it eliminates kneeling, stooping, and hammering. The manufacturer states, “Saves your back [by using] leverage, not strength!”
Effects on Productivity:
A demolition bar increases productivity on the worksite.
The QuikRip and Duckbill Deck Wrecker are designed to specifically remove roofing, decking, and subfloor, while the Guster Demo Bar can also remove siding and/or trim because of it’s smaller size.
Using a demolition bar is safer than using a hammer to strike a pry bar when removing roofing, decking, or subfloor. Missing the pry bar with a hammer can result in cuts, bruises, and fractures.
Dan Anton, PT, PhD, ATC; and Kevin Wright, SPT – Eastern Washington University