Treehouse attachment bolt
Encyclopedia
Tree-house Attachment Bolts or TABs, also known variously as Tree Anchor Bolts, Artificial Limbs, GLs (for Garnier Limb), HLs (for Heavy Limb or Hyper Limb), STFs (for Special Tree Fastener or Stud Tree Fastener) are specialized hex cap screws, engineered specifically for treehouse
construction. TABs are used by private consumers and professional
tree house companies worldwide.
Building and Safety building permit
process and in response to dissatisfaction with existing treehouse attachment techniques tested in October, 1997 at the 1st Global Treehouse Symposium in Takilma, Oregon
. Testing conditions were agreed to and a team effort ensued to develop better fastening systems for construction attachments to trees. Factors to measure improvement included safety, load strength and the long term health & vitality of the host tree(s). At the 1998 Symposium, the newly developed TAB outperformed all other attachment systems presented by being less intrusive to the tree, holding more weight, and being easier to install. Michael Garnier has published his recollection of the prototype development and naming of the original product at http://garnierlimb.com. Michael Garnier, with the help of engineer
Charley Greenwood and machinist
Michael Birmingham, added a 3 inches (76.2 mm) collar
onto a 1.25 inches (31.8 mm) hex cap screw to maximize the surface area and minimize compression in the contact area between the tree and the screw. Tests showed that the altered screw could support up to 4 tons. Mr. Garnier was initially the sole producer of these screws and sold them under the product name "Garnier Limb" coined by Jake Jacob in 1999. In 1998 Mr. Greenwood performed tests to determine the crushing strength of the live tissue layer of several tree species, and as a result of this information developed much longer collars than those in use at that time. In 2002 the first Heavy Limb (or HL) variant was installed, and by 2007 single tree installations using four of these fasteners together supported 30 tons placed six inches outward from the tree surface. Sometime after 2007, Mr. Greenwood posted as open source the specifications of what he called a Stud Tree Fastener (STF) on the web and others began producing their own versions. With no patent protection for the basic design, Mr. Garnier trademarked his name in 2010 after one manufacturer started selling an unauthorized version.
or powder coating
for added durability in the elements.
Though TABs vary in size and treatment, all consist of a modified hex cap screw with a threaded end screwed into the tree, a collar (or boss) in the center, and a stem on the outer end terminated in a short threaded section to allow attachment of a nut
. TABs are engineered to achieve two goals:
To achieve maximum strength, TABs are typically produced with at least 1 inches (25.4 mm) diameter threaded steel with a welded collar to increase the surface area
and decrease compressive pressure on the tree's cambia. Too much compression would result in an open tree wound or possible wood fracture. Depending on the species of tree and lever
age distance, TABs of proper design and installation can support weights from 2000 lbs to 25000 lbs.
To minimize interference with tree growth, TABs provide several inches of space between the tree and attached beam and brackets to allow years of continual space for tree expansion as it grows. TABs also require only one hole to be drilled to hold the equivalent weight that multiple, smaller fasteners might have required. Trees often compartmentalize injured areas and multiple closely spaced, small injuries can result a large area being compartmentalized out of the sap flow; this then contributes to wood decay in the compartmentalized area.
The TAB revolution in design has led to the now burgeoning industry of building in trees.
Tree house
Tree houses, treehouses, or tree forts, are platforms or buildings constructed around, next to or among the trunk or branches of one or more mature trees while above ground level...
construction. TABs are used by private consumers and professional
Professional
A professional is a person who is paid to undertake a specialised set of tasks and to complete them for a fee. The traditional professions were doctors, lawyers, clergymen, and commissioned military officers. Today, the term is applied to estate agents, surveyors , environmental scientists,...
tree house companies worldwide.
History
The Treehouse Attachment Bolt was developed to satisfy the safety requirements of the Josephine CountyJosephine County, Oregon
Josephine County is a county located in the U.S. state of Oregon. According to Oregon Geographic Names, the county is probably named after a stream in the area called Josephine Creek, which in turn is probably named after Virginia Josephine Rollins Ort. In 2010, its population was 82,713...
Building and Safety building permit
Construction permit
A construction permit or building permit is a permit required in most jurisdictions for new construction, or adding on to pre-existing structures, and in some cases for major renovations. Generally, the new construction must be inspected during construction and after completion to ensure compliance...
process and in response to dissatisfaction with existing treehouse attachment techniques tested in October, 1997 at the 1st Global Treehouse Symposium in Takilma, Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
. Testing conditions were agreed to and a team effort ensued to develop better fastening systems for construction attachments to trees. Factors to measure improvement included safety, load strength and the long term health & vitality of the host tree(s). At the 1998 Symposium, the newly developed TAB outperformed all other attachment systems presented by being less intrusive to the tree, holding more weight, and being easier to install. Michael Garnier has published his recollection of the prototype development and naming of the original product at http://garnierlimb.com. Michael Garnier, with the help of engineer
Engineer
An engineer is a professional practitioner of engineering, concerned with applying scientific knowledge, mathematics and ingenuity to develop solutions for technical problems. Engineers design materials, structures, machines and systems while considering the limitations imposed by practicality,...
Charley Greenwood and machinist
Machinist
A machinist is a person who uses machine tools to make or modify parts, primarily metal parts, a process known as machining. This is accomplished by using machine tools to cut away excess material much as a woodcarver cuts away excess wood to produce his work. In addition to metal, the parts may...
Michael Birmingham, added a 3 inches (76.2 mm) collar
Collar
Collar may refer to:Human neckwear:*Collar , the part of a garment that fastens around or frames the neck*Ruff collar*Slave collar*Collar , a device of any material placed around the neck of the submissive partner in BDSM...
onto a 1.25 inches (31.8 mm) hex cap screw to maximize the surface area and minimize compression in the contact area between the tree and the screw. Tests showed that the altered screw could support up to 4 tons. Mr. Garnier was initially the sole producer of these screws and sold them under the product name "Garnier Limb" coined by Jake Jacob in 1999. In 1998 Mr. Greenwood performed tests to determine the crushing strength of the live tissue layer of several tree species, and as a result of this information developed much longer collars than those in use at that time. In 2002 the first Heavy Limb (or HL) variant was installed, and by 2007 single tree installations using four of these fasteners together supported 30 tons placed six inches outward from the tree surface. Sometime after 2007, Mr. Greenwood posted as open source the specifications of what he called a Stud Tree Fastener (STF) on the web and others began producing their own versions. With no patent protection for the basic design, Mr. Garnier trademarked his name in 2010 after one manufacturer started selling an unauthorized version.
Design
TABs are usually made using 4140 steel and some go through a heat treatmentHeat treatment
Heat treating is a group of industrial and metalworking processes used to alter the physical, and sometimes chemical, properties of a material. The most common application is metallurgical. Heat treatments are also used in the manufacture of many other materials, such as glass...
or powder coating
Powder coating
thumb|right|Aluminium extrusions being powder coatedPowder coating is a type of coating that is applied as a free-flowing, dry powder. The main difference between a conventional liquid paint and a powder coating is that the powder coating does not require a solvent to keep the binder and filler...
for added durability in the elements.
Though TABs vary in size and treatment, all consist of a modified hex cap screw with a threaded end screwed into the tree, a collar (or boss) in the center, and a stem on the outer end terminated in a short threaded section to allow attachment of a nut
Nut (hardware)
A nut is a type of hardware fastener with a threaded hole. Nuts are almost always used opposite a mating bolt to fasten a stack of parts together. The two partners are kept together by a combination of their threads' friction, a slight stretch of the bolt, and compression of the parts...
. TABs are engineered to achieve two goals:
- Maximise strength and durability
- Minimise tree growth interference and injury
To achieve maximum strength, TABs are typically produced with at least 1 inches (25.4 mm) diameter threaded steel with a welded collar to increase the surface area
Surface area
Surface area is the measure of how much exposed area a solid object has, expressed in square units. Mathematical description of the surface area is considerably more involved than the definition of arc length of a curve. For polyhedra the surface area is the sum of the areas of its faces...
and decrease compressive pressure on the tree's cambia. Too much compression would result in an open tree wound or possible wood fracture. Depending on the species of tree and lever
Lever
In physics, a lever is a rigid object that is used with an appropriate fulcrum or pivot point to either multiply the mechanical force that can be applied to another object or resistance force , or multiply the distance and speed at which the opposite end of the rigid object travels.This leverage...
age distance, TABs of proper design and installation can support weights from 2000 lbs to 25000 lbs.
To minimize interference with tree growth, TABs provide several inches of space between the tree and attached beam and brackets to allow years of continual space for tree expansion as it grows. TABs also require only one hole to be drilled to hold the equivalent weight that multiple, smaller fasteners might have required. Trees often compartmentalize injured areas and multiple closely spaced, small injuries can result a large area being compartmentalized out of the sap flow; this then contributes to wood decay in the compartmentalized area.
The TAB revolution in design has led to the now burgeoning industry of building in trees.