Truss Problems

    The above image shows a model of one of the roof trusses in the Stark Union Church.  This model was built by Trustee Bill Joyce to help people visualize the truss structure.  

    In analyzing this model, the weight of the roof is transferred to the outer edges of the truss by the two triangles formed by the vertical queen post, the horizontal 8" x 8" beam, the outer rafter,  and the 6" x 6" support brace located just inside of the outer rafter.  

    Looking at the outer end of the truss, you can see the 8" x 8" horizontal beam is notched to fit over the top wall plate.  This means that the loads from roof truss are all being transferred to the outer wall through only half of the horizontal beam (4" x 8").

   After decades of stress, the horizontal beam developed a crack from the inside of the notch back towards the center of the beam.  This crack is about 4' long and 1.5" wide.

   The crack has caused the bottom of the horizontal beam to drop down forming a sag in the ceiling.  This sag was the first indication of the the truss starting to fail.

    As a first step in analyzing the problem, an insulation company was hired to remove the blown-in insulation from the ceiling of the church.  This allowed engineers and contractors to safely walk through the attic of the church to see what was going on.

   The next step was to take measurements of all the truss components.  These measurements were used to build the truss model, but they can also be entered into a structural analysis and design program that will visually show how loads are being transferred.

    Engineers and experts in post and beam construction are now being consulted with the goal of figuring out how to support the failing trusses in the short term and how to permanently repair the trusses in the long term.