Tree Cabling
What is Tree Cabling and Bracing?
Tree Cabling & Bracing are specific methods of reducing the chances that a tree part will fail by adding structural support. Cabling and Bracing is the process of installing flexible cables or rigid rods between two tree leads/branches with defective unions.
Situations that may call for Cabling and Bracing include:
A tight fork or codominant trunk or branch union.
When two tree stems press against each other, as they grow they will increase in diameter, and push against each other. The wood fiber from either side never connects and bark is compressed in between the two trunks. If left unaddressed, this can potentially split the union. This split may begin unnoticed inside of the trunk, or it may begin to form a crack on the outside. Tree forks with cracks can be dangerous. Fortunately if this is identified early on, the two trunks can be "tied" together so that they do not completely break apart. This may be done in the form of bracing rods, and or cabling. Also known as Tree Cabling and Bracing.
Oversized (Disproportionately Large) Limbs
Trees will extend branches for many reasons, put the most important reason is to access sunlight. These limbs and branches tend to be heavy because of all the wood fiber, water and leaf material that it needs to be strong enough to hold up to gravity and winds. The physics principle of leverage applies here when the union where the branch connects to the trunk, is introduced to the force of gravity spread over the length of the limb. This can concentrate a lot of stress on the connection point to the trunk, especially when limbs are overextended, or the union is poorly structured/connected. In some cases wind and storms will apply too much force on the limb and it will fail and break. Sometimes the limbs will hang in the tree, and others they will fall onto whatever is below such as houses, streets, cars or even people. By installing cabling, and potentially pruning to reduce some of the weight, these incidents can be prevented.
Decay
Yet another situation that could be appropriate for cabling are trees with some decay. It must be determined that the decay is not advanced or a fast spreading disease, and that there is sufficient structure to build a cabling and or bracing system off of. This can be determined by one of our Arborist Representatives and our guidance and consulting services. In general hollow trees only need a thin stem all in order to be green and look healthy. Measurements and calculations can be done to determine whether there is sufficient strength for a cabling system.
Cracking
Cracking can form from several different causes. When temperatures drop abnormally low, or very rapidly, there is potential for cracking to occur. Wind and storms can strain a trunk or limbs enough to cause splitting, and even lighting can superheat and expand the water into vapor within trees enough that they will crack, and in some cases completely explode. Old cracks that may have happened years ago may be hidden by response growth over the vertical portion of the crack. It may appear as a rib parallel to the trunk or limb. Bracing may be a solution for these issues as well.
Preventatively
In this instance, there may not be a visible concern or issue with the structure of the tree, but as an extra measure of safety during storms, cables may be installed for peace of mind. Although not a guarantee, when installed properly cables can reduce the chances of damage resulting from failed tree limbs. If limbs or trees are damaged in storms, we provide 24/7 emergency storm response.
Cabling and Bracing The Right Way and The Wrong Way
When installed properly, Cabling can strengthen weak tree structures and provide an inexpensive “insurance policy” against property damage. However, when installed improperly, Cabling can create additional hazards. This can happen when installed too low in the canopy or when the wrong cable strength is selected.
All trees have an inherent level of risk -- as even healthy trees can be damaged in a storm. It is important to consult with your Arborist Representative to determine if a Cable system or Bracing rods are the best solution for poor tree structure. Cable systems also have a lifespan and will need to be replaced over time (typically 10 years), so visually inspecting the Cable every year is part of our recommended best practices.
When To Consider Cabling & Bracing
Poor tree structure, such as when co-dominant stems have included bark, is when we want to consider Cabling and Bracing. When two tree stems get bigger over time, they will eventually grow into each other and essentially push each other apart. This, coupled with high winds, may lead healthy trees to fail and split.
Damaged trees, at times, can be restored by installing cables or bracing rods. Whether the tree has an active split or if the branch already failed, cable systems can help prevent further damage.
Hazard mitigation is another reason to cable and brace trees. When trees are planted near highly populated areas, such as playgrounds, it is important to make sure the large limbs will not fall and cause injuries or property damage.
When viewed from afar, the tree cables are barely noticeable even when the tree is defoliated. Typically it is recommended that cabling be installed at a minimum of two-thirds (2/3) of the way up the tree for maximum support. This may vary if the branching structure requires a custom configuration.
Viewed from close up, the sythetic cabling is more visible and one can see in the middle of the span, there is a wider section of cable. This is wider because a rubber shock absorber has been installed in the center of the cabling so that quick and heavy bursts of wind do not jerk the cable and 'shock load' the system. In other words, the shock absorber has a dampening effect on the system. See Cobra Cabling.
