Ladder Roof Access: The Critical Moment
Stepping onto or off a ladder at height should be one of the roofing contractor’s most serious safety concerns.
Ladder hazards certainly arrived with the first prehistoric ladder constructed from a dead tree trunk leading up to a cave dwelling. While portable ladders have changed since then, gravity has not, so making sure workers are trained to use them properly is crucial. All it takes to prove it is a brief look at the statistics.
A recent National Safety Council (NSC) study cited some 300 ladder-related deaths and more than 130,000 non-fatal accidents every year. According to the Center to Protect Workers’ Rights (CPWR), as many as 92 percent of all falls each year from sloped roofs launch from the eaves, where ladder access ways are commonly established. As with most construction site incidents, a key root cause of many ladder-access accidents involves the transfer of loads to and from the rooftop. The act and conditions of an employee stepping onto or off a ladder at height should be one of the roofing contractor’s most serious safety concerns.
When we look at the Electronic Library of Construction Safety and Health (eLCOSH) chart for falls from construction ladders (Figure 1), it shows that the dislodged ladder accounts for 40 percent of all roof falls. The breakout graph subcategorizes the types of ladder movement. One quarter of these falls were caused by the bottom of the ladder “kicking out” and another 9 percent by the top sliding sideways (which may lead to a kick-out). There are cases when lateral displacement may not actually topple the ladder but will cause the worker’s center of gravity to extend beyond the support of the ladder, ultimately causing a fall.
Transitional forces are imposed when a roofer gets on or off a ladder when accessing or leaving the roof deck. All forces are comprised of two components: magnitude (foot-pounds) and vector (direction). Under most conditions, it takes as little as 9 foot-pounds of force to dislodge an unsecured ladder occupied by a 200-pound worker when resting on a metal gutter, and only 16 foot pounds of force when the ladder is resting against a plywood deck edge. When a roofer sidesteps off of the top of an extension ladder reclining at the ANSI-recommended 75.5 degrees (4:1) against the eave, the Law of Conservation of Energy is demonstrated. The law holds that energy can be neither created or destroyed, but only transferred (or transformed) from one form to another. A ladder side discharge converts stored (potential) energy into active (kinetic) energy. The roofer’s mass, which previously stabilized the ladder, decreases in magnitude while his trailing foot discharges the remaining force in reaction to his shifting center of gravity. Both of these reactions are capable of (1) moving the ladder;(2) causing the lead foot to miss or slip; and (3) shifting the worker’s center of gravity and causing a loss of balance. All three of these effects add up to a extremely high potential for a fall from either the ladder or the roof during load transfer.
The direct cause of most roof-ladder-access accidents can be traced back to one or more of the following acts or conditions:
- Poor housekeeping.
- Non-compliant use.
- Improper footwear.
- Defective or damaged ladders.
- Lack of ladder stabilization.
- Inadequate training.
- Insufficient competent person (CP) site safety audits.
After identifying the most likely ladder hazards on site, the employer’s CP for ladders should consider implementing one or all of the following six practical hazard abatement methods:
- Inspect ladders and accessories prior to use and regularly during use for visible defects to ensure they are maintained in their original condition of manufacture.
- Set up your ladder in a 4:1 pitch, utilizing adjustable legs on uneven surfaces or securing base with ground stakes on unstable soils.
- Keep a 3-foot-square (minimum) discharge area clean from debris at the top and bottom of the ladder. Roofers should always avoid carrying any item which prevents 3-point contact during climbing.
- Install either a roof-mounted or fascia-mounted ladder stabilizer to the top of the ladder to prevent unintentional lateral displacement.
- Install two temporary ladder rail extensions to permit straight walk-through to the rooftop and eliminate sidestepping, while also providing adequate 36-inch-high stabilizing handholds.
- Wear footwear appropriately designed for roofing operations in order to maximize traction on pitched roof/ladder bearing surfaces. Gum or consumable rubber soles without heels are recommended. Special care should be taken to keep the soles of boots clean from tar, adhesives, oil, grease and debris, which could cause loss of adhesion.
Employee training in Safe Work Practices (SWP) for portable ladders is the essential principle before using any ladder. The employer’s written Ladder Safety Program should be reviewed at least annually by those governed by it. Refresher training is always recommended, as portable ladder use and condition continue to be a leading root cause of falls on construction sites nationwide.
Ladder Safety Program
According to a 2013 National Safety Council and Consumer Products Safety Commission report, there were 390 ladder-related fatalities and 165,000 injuries requiring medical treatment nationwide in 2012. An American Journal of Preventative Medicine study of ladder accidents from 1990 to 2005 determined that more than 2 million serious ladder injuries were incurred during that period, with more than 10 percent requiring hospitalization. The most common non-fatal injuries (88 percent) were spinal and bone fractures. More than 90 percent of these accidents occurred at residential worksites, and 77 percent of the victims were male. The portable extension ladder is one of the roofer’s primary tools — one that is typically used daily. The evidence suggests the ladder is also, more likely than not, the single piece of construction equipment most prone to operator complacency during use, as well as physical abuse and neglect over time. Workers have to exercise proper caution at all times, especially at the crucial moment when they are stepping onto or off a ladder at height. A well-designed, trained and implemented Ladder Safety Program will be the roofing contractor’s best insurance policy. Profits cannot be maximized until losses are minimized, so safety must always come before productivity. Falls from access ladders are not, and never will be, affordable.