Cabling, Bracing & Screw Rod Installation Services
" Mother Nature " is not always perfect. Many trees have structural defect that they can live with for years. If the tree is on your back border then you would probably not spend the money to try and rectify damage that may occur during high wind periods. If the tree is a feature plant on your property and has some structural defects. Then you need to read on as what can be done to help extend the life and enjoyment you can get from this tree.
Cabling is a simple process of installing permanent wire from one leader in a tree to another for the sake of holding the tree together during high wind. The cable actually braces both leader allowing some movement but stopping most winds that would cause the leader to split at the main trunk. The cable must be installed at ¾ the way up the leader and must have a straight direct line to the other leader. This would be a one way cable. There could be a two way cable with one leader cabled to two separate leaders if there is no direct straight line. Most of the time if this is the only option we would try to may this a three way cable system with all leaders have two splices on the same eyebolt. Once the type of cable system is determined the lines have to be found. These lines can be somewhat determined from the ground but will probably change slightly once we are up in the air. We drill a hole all the way through the leader and install a forged eyebolt which is one solid eye on the bolt with threaded back side with a washer and a nut. The leader must be winched together to get the right tension. Further tension can be tightened with the nut. Too much tension is worst than no cable at all. Cables that go from the top of a leader down to a lower leader should be avoided unless the are attached to the back of a direct straight line cable already installed.
Large feature trees can have a quite extensive cabling system. The tree will grow around the eyebolts giving even more strength. As the tree grows the first set of cable will eventually become lower in the tree canopy. When the cables are at 50% of the canopy height you may want to install a higher set of cables. This rarely happens. The tree would have to be in the juvenal life stage with a clear structural defect in order to install cables.
Forged eyes, they can't bend out, the hole went all the way through the tree, a washer and nut are put on the other side. The tree has grown around the nut.
A split in the main trunk sometimes we can install two screw rods, threaded rod ¼" - ½" - ¾" depending on the life stage - size of the split trunk. The cable system must be installed before any screw rod installation. Generally the screw rods are installed in pairs making a X pattern across the lateral portion of the split with one screw rod 6" - 12" higher than the other depending on the size of the main trunk. You may put in 2 rods or 4 rods. Drilling a hole all the way through the split, install the rod and place washers and nuts on both ends. Nuts are tightened, excess is cut off and a sledge hammer beans over the excess so the nuts can not back off. The tree will grow over the screw rods.
We have installed many cables and screw rods. The photographs you see below are on a Mature Red Oak , Quercis Rubra, located at our Tree Farm in Lakeville, Ma. The feature tree in the back yard shades the house, patio area and is 75' from the pool. It has 4 screw rods that have been covered by callas growth - wound wood. There are seven support cables in the upper foliar crown. The upper foliar crown was thinned by 20% in 2010. The upper foliar crow was thinned around 2000 and several more cable were installed to the original cable system. The original cable system and screw rod was installed about 1992. There is no doubt in our minds that without the cabling and screw rod installation this tree would not be standing today.
There is a second Oak of the same species with a single direct cable system located in front of our Green house. The original cable was installed in 2000 and the foliar crow was thinned. Thinning was also done in 2010. If you want to look at a quality preservation work to a Mature tree stop by and look for yourself.
Upper foliar thinning is almost always performed with cabling systems. It is generally done before the cables are installed. If done correctly it allows the wind to blow through the tree canopy with less resistance. Therefore less wind stress to the structural defects in the tree.
Cable screw rods