The “barber chair” is a dangerous failure that occurs when felling a tree. This event happens when the tree’s forward momentum causes the trunk to split vertically before the hinge can fold and guide the fall. The uncontrolled splitting releases tremendous tension, causing the lower section of the trunk to kick back violently, often striking the saw operator. The phenomenon is named for the way the trunk base springs upward, resembling an old-fashioned barber chair. Mitigating the forces that cause this failure is essential for a controlled and safe felling operation.
Identifying High-Risk Tree Characteristics
The risk of a barber chair split relates directly to internal stresses within the tree’s wood fibers. A significant forward lean places the wood fibers on the backside of the trunk under immense tension, as the bulk of the tree’s weight pulls in the direction of the cut. When the back cut is made, this tension can overwhelm the remaining wood, causing it to rip vertically instead of folding horizontally along the hinge.
Trees with a high canopy or weight concentrated at the top increase the leverage acting on the base. This long lever arm generates excessive force at the stump, which is why tall, straight trunks are sometimes more prone to splitting. Certain species possess wood characteristics that make them inherently susceptible to this failure, generally those with straight grain that splits easily. Species like ash, white pine, tulip poplar, hickory, and locust carry an elevated risk of a vertical split.
Internal defects, such as rot, cracks, or substantial internal decay, further compromise the structural integrity of the wood. These imperfections reduce the trunk’s strength, meaning the wood cannot withstand compression and tension forces until the hinge is fully engaged. A thorough inspection for these defects must precede any cut, as they can turn a moderately risky tree into a high-risk scenario.
Essential Site and Tool Preparation
Before beginning any cutting, the working environment and tools must be meticulously prepared to support a safe operation. The most immediate safety action is establishing and clearing an escape route for the operator. This path must be cleared of all obstacles and should extend 15 to 20 feet away from the tree, angled about 45 degrees away from the intended direction of fall. This ensures the sawyer can retreat quickly after the back cut is completed.
The felling operation depends entirely on the precision and performance of the equipment. The chainsaw chain must be sharp and the saw must be running at full power to execute cuts quickly and cleanly. A dull chain slows the cutting process, increasing the time the wood is under tension and contributing to a higher risk of a split. Felling wedges and a mallet must also be readily available to manage the forces within the tree.
The intended direction of fall must be confirmed, taking into account the tree’s natural lean and canopy distribution. If the tree is heavily leaning opposite the desired direction, mechanical aids like ropes or winches should be secured to reduce the strain on the wood fibers during the cut. Addressing these environmental and equipment factors creates a controlled setting where precision felling techniques can be applied.
Precision Felling Techniques for Controlled Descent
Preventing a barber chair relies on managing the internal tension of the tree trunk with precise cutting geometry. The first step involves creating the face notch, which should be cut to a depth of one-fifth to one-third of the tree’s diameter. Using an open-face notch, often cut at a 70-degree angle, helps the tree fall cleanly and allows the hinge to function for a longer duration.
The hinge is the narrow band of uncut wood between the face notch and the back cut, and it is the only element controlling the tree’s descent. To prevent a premature split, this hinge must be of uniform thickness, typically maintained at 10% of the tree’s diameter. A hinge that is too thin will snap quickly, while an uneven hinge will cause the tree to pivot or shear unpredictably.
For high-risk trees with heavy forward lean, the technique is modified to alleviate extreme tension before the final cut. This involves executing a bore cut, or plunge cut, into the trunk to establish the hinge wood first. The saw is plunged through the center of the trunk, cutting the holding wood on both sides while leaving the critical hinge wood intact. This technique isolates the hinge and allows the sawyer to cut the fibers that are under the most tension without risking the vertical split.
Once the hinge is established with a bore cut, the final back cut is made slightly above the level of the notch apex. As the back cut progresses toward the hinge, felling wedges should be inserted into the cut and tapped to lift the tree gradually. The use of wedges helps to relieve the tension in the wood fibers, preventing the remaining wood from being suddenly overwhelmed and ripping upward, which is when the barber chair split occurs.