How to build a reciprocal roof: Difference between revisions

Revision as of 18:16, 14 May 2014

Coming Soon! In this page we will describe to you how to build a basic understanding of reciprocal roof construction with step by step instructions.

A reciprocal frame is a class of self-supporting structure made of three or more beams and which requires no center support to create roofs, bridges or similar structures. As quoted from Wikipedia.org

This page is intended to show the basic How-To's of installing a reciprocal roof on a structure.

The reciprocal roof lends itself to round walled structures. This structure is a hexagon, although, an octagon, decagon, or vertex-less/circular one would make installation easier. The reason being that the reciprocal roof pitch is determined by the x distance from the top plate to the tangent of the center ring where the rafters lay reciprocating over each other. If the x distance changes, ex: in a square with four corners the x distance from the center point of the square to the edges of the square box are not equal. It is a greater distance from the center to the corner than to the center of a face/side of the square. Therefore, the pitch of the roof will be shallower at the corners and steeper at the faces. In theory, the non sided circle is the best way to achieve an even pitch around the whole structure making a conical roof.
In this hexagonal structure built in a series of community workshops the roof pitch does vary slightly from vertex to face; but this can be mitigated slightly by placing the rafters a distance away from the vertices.
Enjoy this How-To for educational purposes, if this page does not help or if you are looking for more, here is another reciprocal roof how to with blog The year of Mud Reciprocal Roof Blog, enjoy.

File:Reciprocal Roof Construction 1 Finished walls with no roof.jpg

Round Pole Reciprocal Roof How To:

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   |File:Reciprocal Roof Construction 8 Rafters half way up.jpg |Half the roof is up, not yet trimmed. |8 |In this step we can see about half the rafters up.  Notice the relatively even distance between the rafters at the top plate.  Also notice how long many of the rafters are, each one adjusted around until well set.  <br />The ends will be cut off before we release the charlie stick. <br />Leaving the ends long also lets us choose the length of our eave.
   |File:Reciprocal Roof Construction 9Temporary Rafter Ties.jpg |Temporary ties holding the rafters from slipping down. |9 |Here we are with about the first 12 rafters up.  Temporary ties secure each pole to the next.  At this stage we are really starting to see the center ring taking shape. <br /> We can slightly adjust the position of each pole but remember, trying to adjust a pole laid several courses back will move every subsequent pole up to the current unless you carefully lift the weight off of the member when adjusting.
-  |File:Reciprocal Roof Construction10 Fitting Last Rafter.jpg |Fitting in the last rafter can be a little tricky. |10|The only really tricky part of a reciprocal roof is fitting in the last rafter to balance the forces. The vertical arrow on the left shows the last rafter on its way up to the last tight spot '''underneath''' the first rafter placed on the charlie stick indicated by the upper arrow. <br />In some cases the space is too small and a little lifting of the first is required. In other cases, the gap for the last rafter is too big and the charlie stick has to be let down a little to get the gap to close.  <br />Both maneuvers have the potential to knock the center ring out of center so be careful. In this the last rafter was [http://www.theyearofmud.com/2008/11/26/how-to-build-a-reciprocal-roof-frame/ tight], and loose in this one.
+  |File:Reciprocal Roof Construction10 Fitting Last Rafter.jpg |Fitting in the last rafter can be a little tricky. |10|The only really tricky part of a reciprocal roof is fitting in the last rafter to balance the forces. The vertical arrow on the left shows the last rafter on its way up to the last tight spot '''underneath''' the first rafter placed on the charlie stick indicated by the upper arrow. <br />In some cases the space is too small and a little lifting of the first is required. In other cases, the gap for the last rafter is too big and the charlie stick has to be let down a little to get the gap to close.  <br /><br />Both maneuvers have the potential to knock the center ring out of center so be careful. In this the last rafter was [http://www.theyearofmud.com/2008/11/26/how-to-build-a-reciprocal-roof-frame/ tight], and loose in [[https://www.youtube.com/watch?v=QanmUUG2wes this one]].
-  |File:Reciprocal Roof Construction 11 Adjusting the Charlie Stick and Layout Ring.jpg |Hexagon Structure Awaiting a Reciprocal Roof |11 |Whatever you do in step 11.
+  |File:Reciprocal Roof Construction 11 Adjusting the Charlie Stick and Layout Ring.jpg |Final adjustments of the center ring. |11 |In this step some of the temporary ties were removed from the rafters to adjust the shape of the center ring slightly. In this case, the charlie stick was placed just a little too close to the center ring and was becoming stuck, and the gap for the last rafter was a little big, so a little shaking of the charlie stick and half the rafters got it to drop into shape.  <br /><br />I would '''NOT''' attempt to do this much adjusting if i were using rafter poles over 6 inches in diameter, the weight at the top would be too great and the possibility of collapse much higher.  <br /><br /> Also notice from Step 6, the charlie stick is '''outside''' the center ring and can be freely kicked out when the time comes
   |File:Reciprocal Roof Construction 12 Cut off Ends of Rafters to Desired Length.jpg |Hexagon Structure Awaiting a Reciprocal Roof |12 |Whatever you do in step 12.
   |File:Reciprocal Roof Construction 13 Wire wrapping center ring.jpg |Hexagon Structure Awaiting a Reciprocal Roof |13 |Whatever you do in step 13 [[File:Reciprocal Roof Construction video Removing the Charlie Stick Video.flv]][[File:Reciprocal Roof Construction Removing Charlie Stick SWF.swf]]. There is also a video on the removal of a charlie stick on a bigger scale at [http://www.small-scale.net/yearofmud/2008/11/26/how-to-build-a-reciprocal-roof-frame The year of Mud Reciprocal Roof Blog]