Treehouse attachment bolts or TABs are specialized bolts engineered for treehouse construction. [1] [2] [3] Various models and trademarks exist, with names such as Garnier limbs (GLs); tree anchor bolts; artificial limbs; heavy limbs or hyper limbs (HLs); special tree fastener or stud tree fastener (STFs).
They may be either of through fastener style (for smaller trees) or side mount type for larger ones. [1]
One of the main features of TABs is their strength, requiring fewer tree penetrations for robust fastening of a treehouse and hence less damage to a live tree. A typical TAB consists of a threaded metal bolt and a larger diameter collar. The latter provides an extra bending strength by bearing upon the compression strength of the tree grain. [1] Since treehouses are subject to frequent load reversal produced by winds, TABs must be made of spring steel [1] The bolts are able to support from between 9,000 and 12,000 pounds (4,100 and 5,400 kg), [4] a much greater load than conventional lag bolts.
TABs are commonly used in conjunction with pipe brackets, allowing the treehouse structure to move independently with the tree. [2] [5] [6] [7] [8] TABs are designed so a tree's added girth can further envelop it. [9] [10]
The concept of using a collar or large cylindrical object to increase shear strength in wood construction has been around for several centuries in the forms of split rings and shear plates. [11] Shear plates provide a larger load-carrying capacity in shear than can be otherwise achieved by a bolt alone. [12] Because this idea utilized less bolts for equal strength, it transferred well into the use of live trees, as they compartmentalize more efficiently with a single, larger cut than several, smaller cuts. [13] Michael Garnier became involved in treehouse construction [4] [14] beginning in 1990 when he built his first treehouse in Josephine County, Oregon. Two years later, he was ordered by County official to close the treehouse to the public. He began developing what would become the Garnier limb, a high-strength alloy steel engineered bolt that can be screwed into a bore in the trunk of tree. In 1997 Garnier met Arborist Scott D. Baker who shared his knowledge of tree biology and tree structural responses. By 1998, Garnier had developed a commercial bolt product which he called Artificial Limbs. The Garnier limb was primarily developed to satisfy the safety requirements of the Josephine County Building and Safety building permit process. [15] [16]
Engineer Charley Greenwood, with the help of Michael Garnier and machinist Michael Birmingham, added a 3-inch (76 mm) collar onto a 1.25-inch (32 mm) hex cap screw to maximize the surface area and minimize compression in the contact area between the tree and the screw. [17] Garnier was initially the sole producer of these bolts under the names, "Artificial Limbs" and "Garnier Limb". [16]
A rivet is a permanent mechanical fastener. Before being installed, a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite to the head is called the tail. On installation, the rivet is placed in a punched or drilled hole, and the tail is upset, or bucked, so that it expands to about 1.5 times the original shaft diameter, holding the rivet in place. In other words, the pounding or pulling creates a new "head" on the other end by smashing the "tail" material flatter, resulting in a rivet that is roughly a dumbbell shape. To distinguish between the two ends of the rivet, the original head is called the factory head and the deformed end is called the shop head or buck-tail.
A tree house, tree fort or treeshed is a platform or building constructed around, next to or among the trunk or branches of one or more mature trees while above ground level. Tree houses can be used for recreation, work space, habitation, a hangout space and observation.
Bolted joints are one of the most common elements in construction and machine design. They consist of fasteners that capture and join other parts, and are secured with the mating of screw threads.
A clevis fastener is a three-piece fastener system consisting of a clevis, clevis pin, and tang. The clevis is a U-shaped piece that has holes at the end of the prongs to accept the clevis pin. The clevis pin is similar to a bolt, but is either partially threaded or is unthreaded with a cross-hole for a split pin. The tang is a piece that fits in the space within the clevis and is held in place by the clevis pin. The combination of a simple clevis fitted with a pin is commonly called a shackle, although a clevis and pin is only one of the many forms a shackle may take.
Framing, in construction, is the fitting together of pieces to give a structure support and shape. Framing materials are usually wood, engineered wood, or structural steel. The alternative to framed construction is generally called mass wall construction, where horizontal layers of stacked materials such as log building, masonry, rammed earth, adobe, etc. are used without framing.
A fork end, fork-end, or forkend is a slot in a bicycle frame or bicycle fork where the axle of a bicycle wheel is attached. A dropout is a type of fork end that allows the rear wheel to be removed without first derailing the chain.
A scarf joint is a method of joining two members end to end in woodworking or metalworking. The scarf joint is used when the material being joined is not available in the length required. It is an alternative to other joints such as the butt joint and the splice joint and is often favored over these in joinery because it yields a barely visible glue line.
A latch or catch is a type of mechanical fastener that joins two objects or surfaces while allowing for their regular separation. A latch typically engages another piece of hardware on the other mounting surface. Depending upon the type and design of the latch, this engaged bit of hardware may be known as a keeper or strike.
A set screw, also known as a blind screw or a grub screw, is a type of screw generally used to secure an object within or against another object, usually without using a nut. The most common examples are securing a pulley or gear to a shaft. Set screws are usually headless, meaning that the screw is fully threaded and has no head projecting past the thread's major diameter. If a set screw does have a head, the thread will extend all the way to the head. A set screw is almost always driven with an internal-wrenching drive, such as a hex socket (Allen), star (Torx), square socket (Robertson), or a slot. The set screw passes through a threaded hole in the outer object and is tightened against the inner object to prevent it from moving relative to the outer object. It exerts compressional or clamping force through the bottom tip that projects through the hole.
A screw is a mechanism that converts rotational motion to linear motion, and a torque to a linear force. It is one of the six classical simple machines. The most common form consists of a cylindrical shaft with helical grooves or ridges called threads around the outside. The screw passes through a hole in another object or medium, with threads on the inside of the hole that mesh with the screw's threads. When the shaft of the screw is rotated relative to the stationary threads, the screw moves along its axis relative to the medium surrounding it; for example rotating a wood screw forces it into wood. In screw mechanisms, either the screw shaft can rotate through a threaded hole in a stationary object, or a threaded collar such as a nut can rotate around a stationary screw shaft. Geometrically, a screw can be viewed as a narrow inclined plane wrapped around a cylinder.
An eye bolt is a bolt with a loop at one end. They are used to firmly attach a securing eye to a structure, so that ropes or cables may then be tied to it.
A wall plug, also known as an anchor (US) or "Rawlplug" (UK), is a fibre or plastic insert used to enable the attachment of a screw in material that is porous or brittle or that would otherwise not support the weight of the object attached with the screw. It is a type of anchor that, for example, allows screws to be fitted into masonry walls.
Anchor bolts are used to connect structural and non-structural elements to the concrete. The connection is made by an assembling of different components such as: anchor bolts, steel plates, stiffeners. Anchor bolts transfer different types of load: tension forces and shear forces. A connection between structural elements can be represented by steel column attached to reinforced concrete foundation. Whereas, a common case of non-structural element attached to a structural one is represented by the connection between a facade system and a reinforced concrete wall.
Shearing forces are unaligned forces pushing one part of a body in one specific direction, and another part of the body in the opposite direction. When the forces are aligned into each other, they are called compression forces. An example is a deck of cards being pushed one way on the top, and the other at the bottom, causing the cards to slide. Another example is when wind blows at the side of a peaked roof of a house - the side walls experience a force at their top pushing in the direction of the wind, and their bottom in the opposite direction, from the ground or foundation. William A. Nash defines shear force in terms of planes: "If a plane is passed through a body, a force acting along this plane is called a shear force or shearing force."
Out 'N' About is a southern Oregon company that operates treehouse bed and breakfasts and assists with the construction of treehouses. It is located about 10 miles (16 km) Southeast of Cave Junction, Oregon,
A screw and a bolt are similar types of fastener typically made of metal, and characterized by a helical ridge, known as a male thread. Screws and bolts are used to fasten materials by the engagement of the screw thread with a similar female thread in the matching part.
ISO 898 is an international standard that defines mechanical and physical properties for metric fasteners. This standard is the origin for other standards that define properties for similar metric fasteners, such as SAE J1199 and ASTM F568M. It is divided into five (nonconsecutive) parts:
A bolt is a form of threaded fastener with an external male thread. Bolts are very closely related to screws.
Adhesive bonding is a process by which two members of equal or dissimilar composition are joined. It is used in place of, or to complement other joining methods such mechanical fasting by the use nails, rivets, screws or bolts and many welding processes. The use of adhesives provides many advantages over welding and mechanical fastening in steel construction; however, many challenges still exist that have made the use of adhesives in structural steel components very limited.
Pete Nelson, an owner of TreeHouse Workshop, outside Seattle, is an expert in his field: the design and building of treehouses
[Michael Garnier's] battle with Josephine County officials in Oregon began when he built his first tree house, Peacock Perch, in 1990. In May of that year, Garnier sought a building permit from Josephine County Building and Safety to build a tree house, but county officials told him he could not even apply for the license." ...[court battles, national press coverage, testing and development]... "In March 1998, the county accepted Garnier's alternative construction methods and engineering as safe and sound and issued permits for existing tree houses, as well as permits to expand the existing bed-and-breakfast permit.
