I have two barn doors covering an 18' foot opening. The opening has wooden 4x4 at each end, and one in the middle. There are two spans of 2x8, 9' long as a header at the top of the 4x4s.
After hanging the ~9ft barn doors which weight about 100lbs each, the middle of each 2x8 is starting to bow out in the middle, at the top of the header where the barn door hardware / railing is attached.
It seems the weight of the door on the railing is causing too much torsion on the 2x8 header causing the bowing.
To rectify this I was wondering if anyone had thoughts on the best / cheapest course of action. Some ideas we were considering:
Add a 2x4 bracing on the inside of the header to the next parallel member approximately 3ft away. The logic is this will pull the header inwards to counter the force of the barn door pulling the header outward. The problem is putting a screw through the header to the end of the 2x4. The 3.5inch #10 screws did not grab enough into the 2x4, and simply drilled out a hole. I was hoping there was some metal bracketing we could attach instead between the 2x4 and header, though haven't found a suitable piece yet.
A stronger header. I thought about doubling (or tripling) the 2x8 header boards. this is guess work though, I looked around and could not easily figure out the torsional strength of a 2x8 to figure out what was needed. Over time it seems an uncountered load (e.g. from 1) will eventually warp it. Perhaps there is a metal beam which could work, though this is pricey and heavy.
reinforce the header with a metal L beam. I was looking into a long strip of 1.5" x 1.5" L beam and screwing it to the top of the beam. However, the bowing is slight, and I'm not sure the L beam is going to remain rigid enough to counter the load.
Other ideas, or thoughts on what we could do? It's for an old bike shed, so we would like to minimize the costs if possible.
Thanks for your thoughts and insights!