Simple Solutions for Floor and Ground-Level Work:

The Problem

On some construction jobs you need to work close to the ground or floor. For example, you may have to stoop or kneel when installing or finishing slabs, decks, or floor coverings. Bending, stooping, kneeling, or squatting can cause pain in your lower back or knees. Over time you may develop a serious muscle or joint injury. Your risk is higher if you stoop or kneel often or for long periods of time. It is also higher if you twist your body while working in these positions.

These positions can also make it harder to do your job. When stooping or kneeling, you can't lift, push, or pull as much weight without putting stress on your body.

Injuries & Disorders

Below are some of the injuries you may develop when you work at floor level.

Lower back. Your spine runs from the top of your neck down to your lower back. It is made up of many bones called vertebrae, one below another. Between the vertebrae are joints and discs. These give your back flexibility so it can move. The discs are flexible because they have a substance like jelly inside.

When you bend forward, your back muscles work harder and the ligaments (long fibers supporting the back muscles) flex and stretch. The discs get squeezed. As they are squeezed, they can press on different parts of the spine, including nerves. This can cause back pain. If you bend forward over and over for months or years, the discs are weakened, which may lead to disc rupture (or "herniation").

Twisting your body while bending puts even more pressure on the discs, and more stress on the cartilage and ligaments, especially when you are exerting force to lift, push, or pull objects.

Knee. The muscles in your knee are connected to your leg by tendons. Between the tendons and bones are small sacs of fluid called bursa. They lubricate the knee so it moves easily.

Continual stress on your knee can cause the bursa to get squeezed, swollen, stiff, and inflamed (bursitis). This stress can also cause the knee tendons to become inflamed, resulting in pain (tendinitis).

Tasks that involve frequent stooping, kneeling, or squatting increase your risk of developing bursitis, tendinitis, or arthritis in the knee. The risk of arthritis increases for workers who already have had a knee injury and work in these positions.

Some Solutions

Floor-level work cannot be eliminated from construction, but it is possible to change how you do it so it is easier on your body. Solutions are available that can reduce the level of stress on your back, knee, and other parts of the body. They may also reduce how often and how long the body is subjected to this stress. Many of the solutions can also eliminate other potential safety hazards and increase productivity.

The type of task and the site conditions will determine which solutions are best for you. A few possible solutions for specific floor-level tasks are explained in Tip Sheets #1-5.

General solutions for doing floor-level work with less risk of injury include:

Change materials or work processes. One of the most effective solutions may be to use materials, building components, or work methods that are less labor-intensive, so the task takes less time and you therefore kneel and stoop for a shorter period. Because there may be cost, contract, and engineering issues involved, an individual construction worker or subcontractor usually cannot make a decision like this. Changes may require the approval of the architect, engineer, building owner, or general contractor.

However, individual workers often can change the way they do the work. Sometimes people work on the floor because it is the only large flat work area available. The floor is used as a workbench for assembling, mixing, or other tasks. This is common, for example, when assembling sheet metal ducts or building rebar cages. This increases the amount of stooping or kneeling that is necessary. Rather than stooping to the floor, try to raise the work to waist height using tables, sawhorses, or other equipment. It is possible to make your own improvised workbench out of materials you have available.

Change tools and/or equipment. For example, use tools with extension handles that let you stand up while doing a floor-level task. In a few cases, cost and site conditions may restrict the use of such tools.

Change work rules and provide training. Contractors can set site rules that require the use of benches, tables, or sawhorses to raise the work up so less kneeling and stooping are necessary. Rules can also require that materials be stored off the ground. Limits can be placed on the total time that workers do floor-level work without a break. In cases where kneeling on a hard surface cannot be avoided, knee pads or some other type of padding should be used. Also, a policy of providing ergonomics training may help workers more quickly identify potential problems and find effective solutions.

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TIP SHEET #1 Fastening Tools that Reduce Stooping

The Problem

When working at floor or ground level, construction workers often use screw guns and other fastening tools that require stooping, bending, kneeling, or squatting for long periods of time. Working repeatedly in these positions can result in fatigue, pain, and injury. Your lower back and knees are the areas at greatest risk of a muscle or joint injury when you stoop, bend, kneel, or squat for prolonged periods. Your risk is increased if you have to lift, push, or pull while stooping.

One Solution

Use an auto-feed screw gun with an extension that allows you to stand upright while working. Standing while you work keeps your spine and knees in a neutral position, minimizing strain and muscle fatigue. Many stand-up tools have adjustable lengths to fit workers of different heights. Stand-up screw guns that automatically feed the screws are available. Powder-actuated fastening tools (PATs) can be used with a stand-up handle provided by the manufacturer.

How It Works

A screw gun with an extension can be used to secure subflooring, false floors, and decking; to construct concrete forms; and to do other wood-to-wood jobs. You can also use it for drywall and some metal-to-metal work. Screws for these guns come on easy-loading, collated strips that are self-feeding. They load in seconds without requiring you to bend down, and the newer models have been improved so they do not jam like older models. There are models with fixed and telescoping extensions. Some use extensions that can be removed, allowing the screw gun to be used by itself for walls.

A powder-actuated fastening tool with a stand-up handle can be used to fasten metal track to concrete decks for interior steel framing, to install plywood onto concrete as a substrate for wood floors, to attach lumber to concrete and masonry, and to make steel-to-steel connections. These are a fast, reliable, efficient fastening method that can be used independent of weather conditions. They fire a .27-caliber explosive charge to drive their fasteners. The fasteners are made from hardened steel and have a knurled shaft to anchor them securely in the base material. Pre-drilling holes is not necessary. The driving depth can be adjusted for varying jobsite conditions. Hearing protection is advised when firing PATs.

Benefits for the Worker and Employer

Workers who spend less time in a stooped position, or kneeling, have less chance of developing lower back and knee injuries. Productivity is also improved. Studies have shown that autofeed stand-up screw guns are about twice as fast at placing screws as traditional screw guns. Both stand-up screw guns and PAT tools with stand-up handles have improved since they were first introduced and are now more dependable and easier to use. Screws are more expensive than nails and may not be cost-effective for some jobs. However, using screws may improve the quality of construction on other jobs, such as installing subfloors.

Approximate Cost

Stand-up screw guns are $200-400. PAT fastening tools with stand-up handles are $500-700. The PAT handles can also be purchased separately

For More Information

• Products related to this solution are described at www.cpwr.com/simple.html. Products also may be found on the internet using the following search terms:

  Stand-Up Screw Guns: "screw gun extension"

  Powder-Actuated Tools with Stand-Up Handles: (tool manufacturer) + "stand-up handle"

• Local contractor tool and equipment suppliers or rental companies may be another source of information on products.
• For general information on this solution, check www.cpwrconstructionsolutions.org and www.elcosh.org.

TIP SHEET #2 Motorized Concrete Screeds

The Problem

When you hand screed concrete, you work bent over, and you have to use a strong grip to pull the board over the wet concrete. Your arms and shoulders exert a lot of force over and over. Doing this work often or for a long period of time increases your chance of fatigue and pain. It puts major stresses on your back, knees, hands, arms, and shoulders, which may lead to serious muscle or joint injuries.

One Solution

Use a motorized screed (also called a vibratory screed). You can work standing upright, and operating the screed takes much less effort than hand screeding. This type of screed eliminates both screeding in a stooped position and the need for repeated arm and shoulder movements.

How It Works

The motorized screed consists of a blade or plow that floats on the concrete, one or two gasoline motors that vibrate the blade, metal support tubing, and handles to hold when you operate it. It works best for small to medium-sized jobs.

Benefits for the Worker and Employer

A motorized screed should reduce a worker's chance of developing muscle and joint injuries. This equipment greatly reduces the physical effort needed for hand screeding, and eliminates the frequent and prolonged stooping. Little effort is needed to move the plow over the concrete surface.

Screeding with motorized equipment can be faster than hand screeding. Many contractors report improvements in productivity. The vibration of the blade improves the consolidation of the concrete and reduces time spent "bull floating" the surface.

There are some drawbacks. Although you can work around electrical or plumbing stubs, some hand screeding may still be necessary. Also, it can be difficult to move the screed to and from the work location. A single-engine screed weighs around 50 lbs., and can be awkward to lift and carry. Some screeds have a quick-release system to remove the plow from the frame, which makes carrying easier.

Vibration can also be a problem. It is important to protect workers from hand-arm vibration syndrome (HAVS), a nerve disorder that can become disabling. NIOSH measured vibration levels on three types of motorized screeds. Two had the gasoline engine placed at the bottom of the frame and above the plow. One screed had the engine placed on a single shaft, and the operator held the shaft below the engine. Vibration levels for the two types with the engine at the bottom were below the current recommended guidelines to prevent HAVS. The third screed, which was also older and poorly maintained, gave off much higher vibration that could exceed current HAVS guidelines. Higher vibration levels are expected when the engine is connected to the frame or shaft that the operator must grip. When buying a motorized screed, ask about vibration levels and test drive the screed.

Approximate Cost

A single-engine motorized screed costs around $1,500. A twin-engine model costs around $4,000 and requires two operators.

For More Information

• Products related to this solution are described at www.cpwr.com/simple.html. Products also may be found on the internet using the following search terms: "power screed," "vibratory screed," or "concrete screed."
• Local contractor tool and equipment suppliers or rental companies may be another source of information on products.
• For general information on this solution, check www.cpwrconstructionsolutions.org and www.elcosh.org.

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TIP SHEET #3 Rebar-Tying Tools

The Problem

Ironworkers tie rebar by hand with pliers and tie wire. This work requires repeated, fast hand and arm movements while applying a lot of force. If you tie rebar at ground level, you also have to work in a stooped position, with your body bent deeply forward.

Tying rebar by hand increases your chance of developing hand-wrist disorders due to the high hand forces used to grip pliers, the rapid hand movements used to wrap and twist wire, and the high pressure on the hand and fingers when twisting and cutting wire. If you work at ground level, you also are at risk of low back injuries from frequent and prolonged stooping and bending.

One Solution

Use a rebar-tying tool. This lowers your risk of hand and wrist injury because it eliminates the frequent rapid hand motions required when using pliers. Some rebar tiers allow you to work standing up, so there is less stress on your low back due to stooping and bending.

How It Works

Both manual and battery-powered rebar-tying tools are currently available.

Battery-powered rebar tiers automatically fasten the bars together with tie wire. They can be used whenever a simple "wrap and twist" tie is needed. However, they do not provide the strength of "saddle" or "figure 8" ties.

Several companies offer power rebar tiers. With one tool design, you press the trigger and the tool feeds wire around the bars and then twists and cuts the wire. These models are not stand-up tools, but an adjustable extension handle is available.

A second tool is a stand-up power tier that uses coiled spring wire to hold the bars together. The tool automatically "screws" (or spins) flat coiled wire around the intersecting bars. This tool was designed using ergonomic principles.

Benefits for the Worker and Employer

Workers should experience fewer injuries. Studies conducted by NIOSH and the Construction Safety Association of Ontario (Canada) compared manual methods and one model of power tying tool, and showed that using the power tool may reduce the risk of injury to workers' hands, wrists, and low back.

There have been documented increases in productivity. The NIOSH-Ontario studies found that power tying tools can tie rebar twice as fast as hand tying. Actual productivity increases will depend on the type of work and the frequency of tying. Also, contractors and rod busters who used the model of power tool involved in the studies reported they preferred it to manual tying for flat work. Before using one of these tying tools, make sure the ties are approved for the job you will be doing.

Approximate Cost

Wire feeding tiers are under $2,700 and wire costs around 2 cents per tie. Tiers using coiled spring wire are under $1,300 and wire costs around 3 cents per tie. Powered models generally require extra batteries and chargers, which may be included in the price.

For More Information

• Products related to this solution are described at www.cpwr.com/simple.html. Products also may be found on the internet using the following search terms: "rebar tying system" or "rebar tier."
• Local contractor tool and equipment suppliers or rental companies may be another source of information on products.
• For general information on this solution, check www.cpwrconstructionsolutions.org and www.elcosh.org.

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TIP SHEET #4 Kneeling Creepers

The Problem

Many construction tasks require frequent kneeling, squatting, or stooping because the work is close to the floor. Kneeling on a hard surface puts a lot of direct pressure on your knee, while squatting puts stress on the tendons, ligaments, and cartilage of the knee joint. Working in either position often or for long periods of time can lead to knee problems, including knee osteoarthritis.

If you work in a stooped position, there is stress on your lower back as well as your knees, possibly leading to back pain and even a serious back injury.

One Solution

Use a portable kneeling creeper with chest support. When the job requires kneeling or squatting to work at floor level, these devices will reduce the stress to your knees, ankles, and lower back.

How It Works

Kneeling creepers are available with removable seats and cushioned knee supports. They are very low and have 2 to 3 inch casters. The knee supports on one model are only 3/4 inch above the floor. The cushioned knee supports reduce the pressure on your knees, just as ordinary knee pads do.

Some models are available with an adjustable cushioned chest support. It is useful when doing prolonged floor-level jobs like tile setting and concrete patching. It helps support your weight, reducing back strain and some of the pressure on your knees.

Benefits for the Worker and Employer

Kneeling creepers provide support when work must be done in awkward and stressful positions. They reduce stress on the knees and lower back, and can help prevent serious muscle and joint problems. Since work can be done with less discomfort and pain, productivity often also increases.

Kneeling creepers allow workers to move around more easily and quickly, and may also have an area where tools can be conveniently placed.

These devices can be used to assist injured workers retuning to the job, since they can work with less stress to their knees and back.

Approximate Cost

Kneeling creepers without the chest support cost around $200 and the optional adjustable chest support is around $75.

For More Information

• Products related to this solution are described at www.cpwr.com/simple.html. Products also may be found on the internet using the following search terms: "kneeling creeper."
• Local contractor tool and equipment suppliers or rental companies may be another source of information on products.
• For general information on this solution, check www.cpwrconstructionsolutions.org and
  www.elcosh.org.

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TIP SHEET #5 Adjustable Scaffolding for MasonryWork

The Problem

Masons often need to stoop to pick up brick, block, and mortar and place them on a wall. This work can require a lot of bending and twisting of the body.

You have to bend deeper and twist your body more often if you keep materials below hip height, or lay brick or block on a section of wall below hip height.

Frequent stooping causes fatigue and puts stress on your lower back. This stress increases your chance of developing low back pain or serious back injury. Your risk of injury is even higher if you also twist your body quickly, especially when holding heavy objects.

One Solution

Use split-level adjustable scaffolding. This allows a brick or block mason to stoop less because the materials and work surface are both kept near waist height, which is more comfortable and stresses your body less. Split-level adjustable scaffolds are available for jobs ranging from small single-story residential work to large high-rise building projects. This equipment may not be appropriate for all jobs.

How It Works

Adjustable scaffolding has separate platforms for the worker and the materials. Since the worker platform can be raised or lowered, the materials and the work surface can both be positioned around the height of the worker's waist. Small scaffolds can be raised manually using hand jacks or a hand winch. Taller scaffolds can be raised using a powered winch.

Benefits for the Worker and Employer

Masons reduce their chance of developing low back pain or back injury. Workers spend less time handling materials because brick, block, and mortar are moved shorter distances. Workers expend less physical effort and report less fatigue at the end of the day. They also appreciate the wider platforms, which give more room to move around.

Mason tenders who build conventional frame scaffolds also get important benefits. Split-level adjustable scaffolds reduce the heavy physical labor involved in continuously changing the height of a frame scaffold. There is less lifting and carrying of frames and heavy boards, and less moving materials to the ground and back. Split-level adjustable scaffolds also reduce the danger of falling that mason tenders face when building frame scaffolds.

Measurable increases in productivity have been reported when split-level adjustable scaffolds are used. One study found that masons' productivity increased 20% when using the scaffolds, and some contractors have reported even greater increases in productivity.

Approximate Cost

Costs vary depending upon how the work platform is raised (manual vs. powered), the height of the masonry wall, and the overall size of the project. Heavy-duty scaffolding for three-story commercial work runs about $300 per lineal foot. Light-duty scaffolding for residential and light commercial work of the same height runs about $200 per lineal foot. Contractors who have used these systems say that productivity increases allow them to recover the cost, but actual benefits will vary.

For More Information

• Products related to this solution are described at www.cpwr.com/simple.html. Products also may be found on the internet using the following search terms: "adjustable scaffolding."
• Local contractor tool and equipment suppliers or rental companies may be another source of information on products.
• For general information on this solution, check www.cpwrconstructionsolutions.org and
  www.elcosh.org.

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