|(1) The swelled-center round design uses hickory hard wood. The changing diameter saves on weight and allows personal secure grip preference. The 12-inch rung spacing is safer and allows for increased leg climbing power when carrying heavy equipment or a victim. (Photo courtesy of ALACO.)|
|(2) Aluminum ladder rungs are hollow and spaced 14 inches apart to gain height and save on weight without decreasing load-carrying capacity. Rungs have serrated or corrugated surface for a firm nonslip grip. The welded-expanded process eliminates looseness and provides the strongest rung-to-beam joint. The rung is as strong as the beam. (Photo by author.)|
|(3) Bangor ladders, in 40- to 50-foot lengths, come with tormentor poles to raise, extend, and stabilize the ladders. The poles also prevent the ladder from bouncing. (Photo by author.)|
I remember seeing a DVD called Iron Men, Wooden Ladders, a documentary about the great Toronto fire of 1904. I liked that title and have never forgotten it. Prior to 1930, all fire service ground ladders were made of wood. Sam Carbis is credited with inventing the first aluminum ground extension ladder in 1930. As building heights grew, the fire service needed ground ladders that were longer but would not be too heavy for firefighters. Carbis started the Aluminum Ladder Company (ALCO), and it has been around ever since. It’s based in Florence, South Carolina, and manufactures the ALCO-LITE ground fire ladders.
Duo-Safety, another aluminum ladder manufacturer, was established in 1931 in Oshkosh, Wisconsin. Together, these two companies have been equipping the fire service with aluminum ground ladders with comparable models ranging from 12-foot attic ladders to 50-foot bangor ladders. Bangor ladders are the largest ground extension ladders, are usually 40 to 50 feet long, and require tormentor poles to raise and stabilize them. Bangor ladders require a minimum of four firefighters to raise and extend. It has been accomplished with three firefighters, but it’s safest to use six firefighters. These are monster ladders.
The tapered-truss, wood ground fire ladder stems from an original design by Frederick Seagrave, who was making wood orchard ladders at the time. In 1881, he began making fire apparatus in Columbus, Ohio. The Los Angeles Ladder Company (LALCO) was established in 1883. At one point in the early 1900s, LALCO made ladders for all the United States fire apparatus manufacturers. Wood ladder manufacturers for the fire service have all but disappeared, but LALCO continued to supply the Los Angeles (CA) City and County Fire Departments, as well as many other southern California fire departments, with its wood ladder inventory. The San Francisco (CA) Fire Department makes its own wood ground ladders in its ladder shop, but its original craftsmen were trained at LALCO. The company was sold in 1982 and is now known as ALACO, based in Chino, California. Many of the LALCO master craftsmen stayed on. Today, the current ALACO crews have more than 30 years of experience in the specialized process of making tapered truss wood ground ladders, all of which are made by hand.
Although Los Angeles City and Los Angeles County are well known for their traditional wood ladders, the Salt Lake County (UT) and Nyack (NY) Fire Departments have also managed to stick with wood ground ladders. And, therein lies one of the great debates among firefighters: Which type of ground ladder is better? There are pros and cons with both. Before reviewing them, here is a note on fiberglass ladders. Many municipal power companies use fiberglass ladders because they don’t conduct electricity. However, when exposed to high heat and flames, fiberglass ladders emit toxic gases. That’s why most fire departments do not use them.
ALACO ladders are made from west coast Douglas fir, oak, and hickory. These species produce the toughest and strongest wood. Longer ground ladders are made of lumber that comes from trees that are 100 to 200 years old, harvested from Oregon’s Willamette Valley. The rungs are hickory hardwood. The rails, beams, and slide guides are made of red oak or fir. All components are fitted to the ladder by hand. The trussed beams reduce weight by eliminating material (wood) that is not essential to the load- carrying design while maintaining the rated strength capacity of the ladder.
Wood Ladder Pros
• Wood ladders do not conduct electricity, protecting firefighters from electrocution when they accidentally come in contact with an unknown live power source.
• Wood ladders do not conduct heat. The insulating value of Douglas fir is superior, comparable to rock wool. If the tip of the ladder is exposed to high heat and flames, the rest of the ladder remains cool to the touch and stays strong. Exposure to flames does not weaken or damage the rest of the ladder. While the exterior layers of wood may be charred or burned, the wood inside the rest of the ladder retains its original strength. This is a considerable plus if you have a victim on the ladder with you. Wood doesn’t anneal, (explained later) and fire damage is immediately apparent and visible.
• Wood ladders resist flexing, allowing for sure and quick climbing with little or no bounce. Douglas fir is not springy like aluminum. The extra deep trusses resist bending.
• The swelled-center rung design saves on weight. The changing range of diameters allows large hands to grab the center of the rungs while smaller hands can grab the rungs next to the beams. Wood ladder rungs are solid wood and are spaced 12 inches apart. Aluminum ladder rungs are hollow tubes spaced 14 inches apart. This allows more ergonomic climbing power for carrying heavy equipment or a victim. After 34 years of climbing up and down and worn out knees, I’d much prefer the 12-inch spacing vs. the 14-inch spacing on my ladders. When you’re carrying heavy equipment in addition to your own weight in full gear, that extra two inches can be a stretch.
Wood Ladder Cons
• Wood ladders are heavier but, depending on the model, some are actually lighter. For the most part this is true, but two-person ladders are still two-person ladders with wood, and all wood ground ladders are being raised with the minimum-staffing crew of four. Because you’re dealing with milled wood, the weights vary but they are usually within 10 percent or 20 pounds of the weight of an aluminum ladder of the same length with the same duty rating.
• Wood ladders are substantially more expensive. Some lengths are cheaper than the aluminum equivalent, but for the larger ladders this is true. For example, where some aluminum ladders cost hundreds of dollars, a comparable wood ladder will cost in the thousands. Lumber is a natural resource; some believe lumber is getting scarce, which would drive up the price, making these ladders cost-prohibitive.
• Wood ladders do require significant maintenance and care compared to aluminum. But a well maintained wood ladder can give you 10 to 15 years of service.
Wood is a natural product; therefore some believe that every tree and board is different, which affects the load limit within specified weight parameters. They also feel wood ages rapidly without proper maintenance. Wood swells and shrinks with changes in temperature and humidity. They feel these would naturally affect and change the load limits of the ladder. Aluminum is not affected by these factors. However, every ALACO wood ladder meets or exceeds National Fire Protection (NFPA) 1931, Standard for Manufacturer’s Design of Fire Department Ground Ladders, and consistently passes NFPA 1932, Standard on Use, Maintenance, and Service Testing of In-Service Fire Department Ground Ladders. Repeated annual tests (required) have not adversely affected well-maintained wood ladders.
Duo Safety and ALCO both make aluminum ladders, and there’s not a lot of difference between them. All ladders meet or exceed NFPA standards, and repeated annual weight tests have not adversely affected the performance and durability of their ladders.
ALCO-LITE rungs have a serrated surface for a firm, nonslip grip for wet gloves and boots. The company boasts easy rung replacement if there is damage or failure that can be performed by firefighters in the field without special tools.
Duo Safety requires that a certified welder replace a rung in the field. But ladders would most likely be switched out because this type of repair is not a typical field repair. They feature 1¼-inch corrugated and welded expanded rungs. This two-step process makes certain that the rungs do not loosen and that the rung joints are as strong as the ladder beams.
Aluminum ground ladders and roof ladders are all rated for 750-pound loads with a 4:1 safety factor. This doesn’t mean they can only carry 750 pounds. Roof hooks are ¾ inch in diameter. Aluminum ladders can be trussed or solid beam. Longer-length ladders with greater load-carrying capacity are usually trussed beam but not always lighter. Many solid beam ladders are hollow, lighter, and rated for lighter carrying loads. Beams are also called side rails. The rungs are spaced 14 inches apart to achieve height without adding weight. They use an aluminum alloy called 6061-T6. The T6 means the metal was heat-treated at 360°F to achieve tensile strength of 42,000 pounds per square inch (psi). Welded 6061-T6 has a minimum yield of 8,000 psi. This makes the strongest rung-to-rail connection possible.
Aluminum Ladder Pros
• Aluminum ladders are lighter, taller, and cheaper. The tallest popular wood ladder is 40 feet; beyond that, they are simply too heavy. Aluminum ladders are made up to 50 feet. That’s one more story of reach.
• Aluminum is more readily available than lumber. There’s no guesswork in the design limits of the material. All the material is consistent. Production and quality control are fast and easy compared to wood. Aluminum assembly lines are not affected by the variances of wood ladder assembly, whether it is the quality of the wood or the experience of the craftsman.
Aluminum Ladder Cons
• Aluminum ladders without tormentor poles tend to bounce during a rapid ascent.
• Aluminum ladders conduct electricity. If the ladder comes in contact with a hot overhead power line, electrocution is possible. Or, consider a hot power line dropping from a burning house onto a chain link fence. If the ladder accidentally comes in contact with the now energized fence, the potential exists for electrocution before the ladder even gets to the house.
• Aluminum ladders conduct heat. Although heat is used to treat and strengthen the ladder during its manufacture, exposure to extreme heat and flames at a fire can have a devastating effect on an aluminum ladder. This exposure, even for a brief moment, may cause the ladder to anneal. This means it loses its original heat treatment and the ladder’s load capacity is greatly reduced, even though the metal shows no sign of damage or change in appearance. An annealed ladder experiences a tensile strength drop to 22,000 psi or less. That can be one half of the ladder’s carrying strength. The annealing process starts at 350°F. Since aluminum is such a good conductor of heat, the entire ladder may become annealed even if only part of it is exposed to high heat.
The higher the heat or the longer the exposure to temperatures of greater than 350°F, the faster and more complete the strength loss occurs. It may not even support the weight of one firefighter. This can be a catastrophic event in the middle of a ladder rescue because the ladder can show no sign of damage or weakness. The failure will occur when the ladder is weighted by a firefighter, a civilian, or both.
Because of this danger, aluminum ladders are required by the NFPA to have four heat sensor labels (dots) placed on each section of ladder. These dots, which are off-white or orange, change to black when temperatures reach 300°F or greater. The color change is nearly impossible to notice at night during a fire. That’s why ladders need to be inspected after every use. A black dot indicates the ladder may have lost 25 percent of its load-carrying capacity and must be placed out of service for testing, repair, or replacement. The dots have an expiration date and need to be changed out every five years.
It’s About Reach
The popularity of tapered truss wood ground ladders is growing; however, with budget crunches and firefighters facing layoffs around the country, aluminum ladders can meet the standard at the lowest bid. The pros and cons of both products are compelling. One thing is for sure, at least in my city: The population is becoming denser. Three- and four-story townhouses are popping up on lots that used to be single-family residences. Many of these townhouses are on the back side of the lot, away from any aerial access. So get ready; that means ground ladders-of wood or aluminum. Just make sure they reach.
RAUL A. ANGULO, a veteran of the Seattle (WA) Fire Department and captain of Ladder Company 6, has more than 30 years in the fire service. He is a member of the Fire Apparatus & Emergency Equipment editorial advisory board. He lectures on fire service leadership, company officer development, and fireground strategy and accountability throughout the United States, Canada, and Mexico.