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Valley truss on existing truss system

Valley truss on existing truss system

Valley truss on existing truss system

(OP)
My client wants to place an additon on the rear of the existing structure (34'X24').  The existing trusses are paralell to the 24' dimension.  the trusses are 27' in length (1'6' overhang on each end) and 5'6"in height at the peak..4.89' pitch.  the addition is 15'X34' with the trusses parallel to the 34' dimension. The existing trusses and the new valley trusses wil be perpindicular to each other 2-0'spacing.  I have the following questions...
1) Is it possible to install a valley kit on the existing roof system starting with a valley truss 34' in length down to 0' in length to meet the existing peak 13.5' away..(intersecting roofs). and
2) When analyzing the additional dead load on the existing truss system would I spread the dead load evenly along the bottom chord #/ft or do I use the point loads indicated by the truss manufacturer where the purlin meets the bottom chord. The home-owner does not have a set of plans for the existing structure(approximatley 10 yrs old).  Section 3403.2 of the 2003 IBC states additions or alterations to an existing structure shall not increase the force in any structural element by more than 5 percent unless the increased froces are in complience with the code for new structures.

RE: Valley truss on existing truss system

I would suspect that the additional dead load on the trusses would be negligible.  If your valley set will be spaced at 2'O.C., then I would say that analyzing the  existing trusses with a uniform load along the top chord would closely approximate point loads.         

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