Treehouse attachment bolt

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. Since treehouses are subject to frequent load reversal produced by winds, TABs must be made of spring steel The bolts are able to support from between {{convert|9000|and|12,000|lbs|kg}}, 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.{{cite book | title=Moon Living Abroad in Costa Rica | publisher=Avalon Travel Publishing | author=Van Rheenen, Erin | year=2010 | pages=375 | isbn=9781598808445}}{{cite web | url=http://land8.com/profiles/blogs/interview-with-pete-nelson-of-animal-planet-s-treehouse-masters | title=Interview with Pete Nelson of Animal Planet's "Treehouse Masters"}}{{cite web | url=http://press.discovery.com/ekits/treehouse-masters/bios.html | title=Pete Nelson – the Treehouse Expert | publisher=Animal Planet | accessdate=28 December 2013}}{{cite web | url=http://animal.discovery.com/tv-shows/treehouse-masters/about.htm | title=About Treehouse Masters | publisher=Animal Planet | accessdate=28 December 2013}}{{cite news | url=https://www.nytimes.com/2013/05/31/garden/pete-nelson-on-the-new-reality-television-series-treehouse-masters.html?_r=0 | title=Houses for Dreamers (and Kids) | newspaper=The New York Times| date=29 May 2013 | accessdate=28 December 2013 | author=Kurutz, Steven | quote=Pete Nelson, an owner of TreeHouse Workshop, outside Seattle, is an expert in his field: the design and building of treehouses}} TABs are designed so a tree's added girth can further envelop it.{{cite news | url=http://tdn.com/mobile/article_b64cf932-e5bb-11e2-bcc5-0019bb2963f4.html | title= Bird's eye brew: Treetop tasting room draws visitors | newspaper= Akron Beacon Journal | date=6 July 2013}}{{cite magazine | url=http://www.outsideonline.com/outdoor-gear/design-and-tech/Elevate-Your-Game-Built-Your-Ultimate-Treehouse.html# | title=How to Build the Ultimate Treehouse | magazine= Outside Magazine | date=October 2013}}

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.{{cite web|url=http://www.treehouseattachmentbolts.com/construction.html |title=History of the TAB |accessdate=2014-02-28}} Shear plates provide a larger load-carrying capacity in shear than can be otherwise achieved by a bolt alone.{{cite web|url=http://www.shearplates.com/ |title=Information regarding shear plates |accessdate=2014-02-28}} 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.{{cite web|url=http://www.thetreehouseguide.com/treedamage.htm#compartment |title=Live tree reactions to TABs |accessdate=2014-02-28}} Michael Garnier became involved in treehouse construction{{cite news | url=http://docs.newsbank.com/openurl?ctx_ver=z39.88-2004&rft_id=info:sid/iw.newsbank.com:AWNB:SPIB&rft_val_format=info:ofi/fmt:kev:mtx:ctx&rft_dat=11B3A9A213E20EB0&svc_dat=InfoWeb:aggregated5&req_dat=0FB3382EE6AD1E46 | title=Northwest Innovators Helped Revolutionize Construction | newspaper=Seattle Post-Intelligencer | date=23 August 2007 | accessdate=28 December 2013 | author=Goodnow, Cecilia}}{{cite news | url=http://docs.newsbank.com/openurl?ctx_ver=z39.88-2004&rft_id=info:sid/iw.newsbank.com:AWNB:MIJB&rft_val_format=info:ofi/fmt:kev:mtx:ctx&rft_dat=0FAA9D222C57A367&svc_dat=InfoWeb:aggregated5&req_dat=0FB3382EE6AD1E46 | title=Refuge among the boughs | newspaper=Marin Independent Journal | date=26 April 2003 | accessdate=28 December 2013 | author=Kugel, Seth}} 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.{{cite book|last=Miskimon|first=Robert|title=The Complete Guide to Building Your Own Tree House: For Parents and Adults Who Are Kids at Heart|year=2008|publisher=Atlantic Publishing Company|isbn=978-1-60138-244-3|pages=88–89|url=https://books.google.com/books?id=7ynNOj4660UC&q=garnier+limb&pg=PA89|author2=Chmienlnicki, Steven |accessdate=29 July 2011|quote=[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.}}{{cite web | url=http://treehouses.com/joomla/index.php/construction/garnier-limb | title=Official Garnier Limb Origin and Histree | publisher=Out'n'About Treesort, LLC | accessdate=28 December 2013 | author=Garnier, Michael}}

Engineer Charley Greenwood, with the help of Michael Garnier and machinist Michael Birmingham, added a {{convert|3|in|mm|adj=on}} collar onto a {{convert|1.25|in|mm|adj=on}} hex cap screw to maximize the surface area and minimize compression in the contact area between the tree and the screw.{{cite web|url=http://www.treehousesupplies.com/TAB-vs-GL-specs_a/266.htm |title=Creation of the TAB |accessdate=2013-09-21}} Garnier was initially the sole producer of these bolts under the names, "Artificial Limbs" and "Garnier Limb".

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Category:Screws

Category:Threaded fasteners

Category:Woodworking