Creating post-free span in Post Barn?

[cattflight]

Greetings. I hope someone can guide me on this one. I am certain many have needed to accomplish this before me.

I have a workshop/barn where I am constructing an airplane. The barn is approx. 26'W x 40'L and it is a timber post construction (photos attached).

Currently there are Qty 3 4" x 5" interior posts that run from the centerline of the barn to the 18' peak at approx. 10' o/c. The distance from each side wall to the center posts is approx. 11.5'. The side walls are standard 16" o/c framing with a top plate. I would like to remove 2 of the posts to create an open span for the workshop area (the third post is fine where it is). This would create a post-free space approximately 24' x 30'.

Supporting the roof rafters are Qty 2 2x10 "Gang Lam" beams (exact dims are 1.75" x 9.25"). These are bolted to opposite sides of the centerline posts and support the rafters just below where they meet a 2x10 ridge beam sitting atop the centerline posts. My hope is to retain these posts from their roof location, cut them approx. 12-13' above the floor, and have them become the vertical part of trusses spanning the 24' width of the barn. Since I am trying to retain as much ceiling height as possible, I would like to construct a scissor truss, but I am not sure if structurally this is OK.

Also worth noting: we live in the countryside on the south end of Denver, CO (and yes, that is a Seahawks flag hanging in the barn. Don't ask!) We get a fair amount of snow. The roof is approx. 8/12 pitch, so I am hoping the load won't require me to eat up all the space above the top plate of the framed walls, which is only 9'.

OK, let 'er rip. Give me your thoughts. I will likely hire a barn specialist or consult a structural engineer to ensure this is done right. I just thought I would start here as a sanity check.

Thanks, all!

 

[Catadj78]

think you are stuck with them

 

[RivennHewn]

A proper sized beam underneath the existing ridge structure that bears on new post alongside the existing post could work, but would most likely require new footings.

A structural engineer will be required.

The Seahawks flag looks good there in Colorado.

How extensive a job is the plane?

 

[cattflight]

A proper sized beam underneath the existing ridge structure that bears on new post alongside the existing post could work, but would most likely require new footings.

A structural engineer will be required.

The Seahawks flag looks good there in Colorado.

How extensive a job is the plane?

Thanks. I was just thinking something similar after researching the scissor truss idea. Perhaps dual beams similar to what's above (or larger) spanning between new posts sort of "sistered" to the front wall and 3rd post interior post? Could work. I'll call an engineer.

To answer your other question....aircraft is about 90% complete with only 90% to go! I anticipate first flight in 2015. The kit is a Glastar made by Glasair Aviation in Arlington, Washington in your neck of the woods. You can check out more of my build activity here.

Thanks for the reply. Go Hawks!

 

[rodm1]

A proper sized beam underneath the existing ridge structure that bears on new post alongside the existing post could work, but would most likely require new footings.

A structural engineer will be required.

The Seahawks flag looks good there in Colorado.

How extensive a job is the plane?

This, Nice shop! The price could be prohibitive definitely contact a structural engineer on this one.

 

[Catadj78]

Anything can be done with the right amount of money thrown at it. I believe the costs would exceed the benefit.

The beams do not appear to have a great amount of vertical or downward load so it may be possible to get away with existing concrete depending on slab thickness. Or else go with a steel beam that would likely require some sort of footer on either end with the vertical support however I find it hard to believe any contractor would touch it without an engineer touching it somehow.

Or just remove the roof all together and install engineered freespan trusses

either of the above may work however again the costs may outweigh the benefit to you, may be able to just build another pole barn for your plane with the money it would take to do the project