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I am wanting to reinforce my pre-fab roof trusses so that I can add a storage area in the attic of my garage. The span of the trusses is 30 feet; they are spaced every 2 feet. The garage is 30' x 30'. I have thought about adding a steel beam across the center of the garage, supported at each end by the wall, and 2 metal posts spaced 10' in from each wall. I would like to place a plywood floor in the center of the attic to store things. Does this sound o.k.? Anyone out there with a better, less expensive, or easier solution? Thanks, Gary  


I assume you are considering adding the steel beam to support the trusses at midspan.  This is not a good idea as it is likely the trusses were not designed for a point of bearing in the middle (some truss styles can take it, some can't).

For such a modification, I would suggest that you get a local structural engineer to look at it.  He can guide you in the modifications and have them meet local codes and standards.

It is relatively easy to modify a truss in such a manner that forces and stresses are redistributed in a dangerous manner. I'm sure you don't want that!



I agree with Ron.  At first glance an additional support might look like a good idea, but if you start putting members in compression that were designed for tension, well................. that's a very bad idea.   


I second both opinions. I had the opportunity to strengthen a O.w.s.j. When I analysed using a temporary support in middle. Every thing gets screwed up. I vaguely remember that support at top chord only was reasonable. Than I added angles on web and rebars on T & B chords. Gettonna bottom line is "It is better to structurally analyse the real situation"

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