Lesson 4-1 LADDERS
Ladders are devices that are used to gain access to work that is performed at higher levels. It is possible to paint the entire exterior surface of a one- or two-story building from a ladder; however, it is often more comfortable and timesaving If a scaffold is erected. Ladders are of several types: single rung, extension, step, and trestle. Each ladder is designed for a specific use and should not be used for any other purpose. Ladders are made of magnesium, aluminum, steel, or well-seasoned wood which is free of knots or other defects.
a. Single-Rung Ladder. A single-rung ladder consists of two side rails that measure from 8 to 30 feet in length. Between the side rails, rungs (steps) are spaced 12 inches apart. Each rung is capable of supporting weights up to 500 pounds. The size of a ladder is determined by its overall length. Although single-rung ladders are available in lengths of up to 30 feet, it is better to avoid ladders that are over 20 feet because of the difficulty in raising them. Figure 4-1 shows a typical single-rung wood ladder. To help keep the bottom of the ladder from slipping, it is necessary to equip it with ladder safety shoes or spikes (Figure 4-2).
Figure 4-1. Single-rung wood ladder
Figure 4-2. Ladder safety shoes
(1) Selecting a ladder. Ladder selection depends on the height at which you must work. You will work most efficiently in a space not higher than shoulder level nor lower than knee level. The length of a ladder is critical because the area that you can safely reach is limited. Use a ladder that is long enough for you to reach your work without climbing past the third rung from the top of the ladder.
(2) Raising and placing a ladder. To raise a ladder (Figure 4-3), place the ladder base against the foundation of the building, raise the top end of the ladder, and walk under it toward the building. As soon as the ladder is perpendicular, pull the ladder bottom out from the building to a distance of one-fourth of the working length of the ladder (Figure 4-4). If it is necessary for you to get on top of a building, the ladder must extend at least 30 inches above the eaves. The ideal ladder angle is about 70 degrees, this is shown on the far right of Figure 4-5. At this angle, the feet of a 28-foot ladder touches the ground about 72 inches from the building. The ratio is 1 foot away from the wall for every 4 feet of the ladder's height.
Figure 4-3. Raising a ladder
Figure 4-4. Placing a ladder properly
Figure 4-5. Getting the right ladder angle
(3) Lowering a long extension ladder. Lowering a long extension ladder requires a helper. To do this, follow the steps as shown in Figure 4-6. In step 1, a helper (shown on the left side of the ladder) braces the ladder foot. As the helper balances the ladder, you need to move out to catch the ladder at its midpoint. In step 2, the helper slowly lowers the ladder as you move toward the top end of the ladder. In step 3, catch the falling ladder and stabilize it by moving quickly toward the top rungs of the ladder.
Figure 4-6. Lowering a long extension ladder
(4) Carrying a ladder. When carrying a ladder, use your arms to stabilize it then carry the ladder horizontally at waist-height (Figure 4-7). A long ladder may require two people to carry it.
Figure 4-7. Carrying a ladder
(5) Using extension planking and ladder jacks. Two ladders may be adapted to hold a scaffold board or extension planking by using one steel ladder jack (Figure 4-8) for each ladder. Mount the jack on the front or back side of the ladder. By placing the ladder jacks between the ladder and the building being painted, you can work closer to the wall. Extension planking (Figure 4-9) is made of well-seasoned material that is straight-grained and free of any knots or defects. Extension planking is available in various sizes and is constructed so that its length is adjustable. As shown in Table 4-1, the size of the lumber used for planking depends on the scaffold span. A scaffold board made of lumber that is straight-grained and free of knots or any other defects may be used in place of an extension planking.
Figure 4-8. Steel ladder jack
Figure 4-9. Extension planking
Table 4-1. Sizes of extension planking
b. Extension Ladder. An extension ladder (Figure 4-10) consists of two or more sections that are adjustable to various lengths. The ladder sections are adjusted by pulling on a rope that is reeved (threaded) through a pulley. The pulley is mounted on the ladder's stationary section, and a rope is attached to the ladder's extension section. The extension ladder overlaps to hold the sections together. The sections will overlap at least 3 feet for ladders up to 38 feet long, 4 feet for ladders up to 45 feet long, and 5 feet for any extension ladders over 45 feet long. Lock the rungs of one ladder section to another section with a secure locking device. Ensure that the ladder sections are in the down position, then erect the extension ladder in the same manner as a straight ladder. After the ladder is erected, lean the top away from the building and raise it to the desired height with the pulley and rope arrangement. Ensure that the ladder sections are locked in place before ascending the ladder.
Figure 4-10. Extension ladder
c. Stepladder. Use a stepladder (Figure 4-11) on flat surfaces where secure footing is obtainable. A stepladder is available in lengths up to 20 feet. Ensure that the brace is extended and locked when erecting a stepladder.
Figure 4-11. Stepladder
d. Trestle Ladder. A trestle ladder consists of two single ladders that are hinged at the top to form an A-shaped device. Erect two trestle ladders and extend planking or an extension platform between the rungs of the two ladders to form a painter's trestle (Figure 4-12).
Figure 4-12. Painter's trestle
e. Ladder Care and Safety. You must keep ladders clean and free from dirt and paint. Protect wood ladders against weather with coats of shellac, varnish, or linseed oil. Do not paint wood ladders because it would hide any obvious defects. Before each use, you should ensure that the locking devices are secure on step and extension ladders. When ladders are not in use, store them in a sheltered, well-ventilated place that is away from weather elements. To prevent warping, hang ladders on brackets by the ladder's side rails. Observe the following additional safety precautions when using a ladder: