Putting a header above trusses or inbetween trusses

15 years ago

I have a 1978 ranch style house. Right now the living room and kitchen are seperated by a 8x4 ft pantry with a 8 ft header on each side with one header thats over a 2x4 wall above block basement and other side is over a 2x6 double header above an opening leading down torwards hallway. I want the space opened up with a flat ceiling. I know the trusses were not factory made but are designed the same. I have had 1 gc tell me that he would put a header up above the trusses to span the difference. I have had another gc want to put a double lvl in between the trusses to span the area. (Cutting out 3" and sliding the header in and attached to each side using hangers.) Hopefully I can paste my diagram to this site somehow because I know this can be confusing trying to fiqure it out. I dont know which way is better and to put a header up there and am concerned which way I should go. and I cant fiqure out how to post my diagram that I created so if anyone would like to look at it I would gladly send it to them. thanks

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mightyanvil

15 years ago

I can't make much sense out of the diagram or the photos because you don't say which way the trusses span, how they are spaced, and the diagram is apparently not to scale (24 ft wall is shown longer than 28 ft wall?)

If the trusses are designed to span the 28 ft dimension of the house, then walls near the mid-span would have no load to carry and could simply be removed. Bearing walls under trusses are rare and would occur at about the 1/4 points where the V-shaped intermediate chords meet the bottom chords. The force at the bottom mid-span of this kind of truss is horizontal tension only. If the headers/walls in question were actually carrying the load of the roof, double 2x10's would be needed (or larger in a cold climate).

So, it appears to me (although I don't really understand enough about this structure to have a clear opinion) that someone might have tried to remedy the bottom chord sag in overloaded or poorly designed and/or fabricated trusses by reinforced them with plywood gusset plates at the connections and adding walls/headers at the mid-span. However, it does seem odd that vertical or angled chords were not added to the truss to transfer load to the walls/headers. Perhaps there are transfer beams along the bottom truss chords extending out 7 ft or so in each direction from the walls/headers. Of course, they would have to be very large inefficient members. Perhaps they span the entire room.

Then again, maybe someone just added some walls and doorways to separate the spaces and used 2x6 headers in case the trusses sagged a bit.

Are there sufficient supports below the wall and the jambs of the opening that take loads to the ground? If not, these walls are definitely not structural. A center beam might have been designed to only carry the floor load. This would be obvious to an engineer.

You should strip all finishes and then have an engineer tell you how to repair the trusses so they can span the entire space without any walls or headers (if you can find one willing to take responsibility for patching a poorly designed truss). If the exterior walls are leaning out at the top plates, then the connections at those points may have failed, spread, and forced the bottom chords downward. Sistering some chords and proper joint reinforcement should make the existing trusses work properly but if the exterior walls are not plumb, you might have to pull them back in place first.

Truss design may look easy but it is a job for a structural engineer. Don't rely on advice about complex structural conditions from a contractor or anyone on the internet. Get an engineer on site.

Your son might be wiser than you think.

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