Steel Connectors for Wood
This is possible the easiest wood connection system. You will cut 9 degrees on the ends of all your wood struts. Your cord lengths (struts) will be measured on the same side and longest side. 20 of these struts lying end to end will create your foundation layout ( the D lettered cord and great circle of the 4V geometry). Using 2X6 materials will give you an R-19 insulation wall using fiberglass
bat material.
Simpson Strong -Tie connectors and strapping are the national engineered
fastening systems for residential and commercial structures. You will find these products in every hardware store. To create your hexagon connector, Simpson makes their Gazebo connector # GT6Z. They are listed under Home Project Connectors in their catalog. You may have to order these. A box of 8 will cost under $50.
The Gazebo connectors come flat and you will bend a 9 degree angle to each end. A pair of 6" C clamps is real handy as an extra pair of hands. 1-1/2"
Philips head wood screws can be used to fasten your connectors to your wood struts. A cordless drill with a magnetic tip makes this an easy task. With your connector lying flat on the side of your wood strut it will stop at the
recessed impression of the connector. All your struts should meet at the same location on every connector.
The inside and outside connectors will all stop on the connector in the same location. The inside connectors will be bent in the
opposite direction as the outside connectors at 9 degrees. Your connectors will find their 9 degree bend by themselves when you have both the connectors
attached to your wood strut with 9 degrees cut on the ends.
The addition of strapping will add to the structural engineering of your connection. Simpson Strong -Tie offers many straps to choose from. # MSRA24Z is the
preferred strap used by Spherical Geodesic Structures. The number 24 refers to 24". Any Simpson strap 18" to 24" X 1-1/4" will work fine. The same 1-1/2" wood screws you use for your connectors can be used for your strapping.
Three straps can cross threw your connection when you use a 2X6 strut. All the weight of your geodesic structure is pushing out on the connections at the lower levels. Adding the steel strapping adds to the structural integrity of the connection system and geodesic structure. The straps have predrilled holes in which to add your screws. The screws are coated and will not rust like nails do.
If you have any spherical design, engineering or building code questions please send us an e-mail and we will try to reply as quickly as possible.
You will have 6 pentagon connectors to make. With some pliers and a hammer you can make adjustments to your gazebo connector. Your strapping will be done in
basically the same way as your hexagon connections. On your vertical strut you will have a strap on each side of the strut. You may want to drill some holes for your screws and bend the corners down.
The plywood is most important to the structural integrity of the geodesic structure. The connection from one triangle to the next relies on end nailing or screwing. OSB or particle board should NEVER be used for exterior sheathing on a geodesic structure. The edges have no
structural strength and it is very susceptible to moisture damage. Multi-ply wood sheathing is the only acceptable standard for geodesic structures. The bottom two rows should be sheathed first. This is the weakest area on the geodesic structure and any other shaped structure.
