Pole Barn Shear Wall

[mattradk]

I am planning a 30'x48' pole barn with a 14' ceiling. I plan to put the posts directly on a footing pad 4' below ground, so the posts will be 18' tall in total. There'll be 8' between posts. The exterior will be steel installed on girts 2'OC.

Many drawings show the use of knee braces between the posts and bottom chord of the trusses to stiffen the building. Instead, I'd like to place 1/2" OSB panels from the skirt board to the tops of the inside wall for a distance of 16' from each corner on the 48' wall, and 10' from each corner on the short walls.

Does this seem reasonable, or do I need the knee braces in addition to the OSB sheets for shear protection? Thanks!

 

[buddyboy]

i might be wrong but i think you need to be on 16" centers when you use sheet goods for sheer...

i used t111 for my exterior and needed the girts to be on 16" centers for sheer.

i would think you could replace the knee bracing with osb as long as the osb was fastened correctly for sheer

but again I don't know I'm just saying that makes sense to me

 

[larry_g]

I am planning a 30'x48' pole barn with a 14' ceiling. I plan to put the posts directly on a footing pad 4' below ground, so the posts will be 18' tall in total. There'll be 8' between posts. The exterior will be steel installed on girts 2'OC.

Many drawings show the use of knee braces between the posts and bottom chord of the trusses to stiffen the building. Instead, I'd like to place 1/2" OSB panels from the skirt board to the tops of the inside wall for a distance of 16' from each corner on the 48' wall, and 10' from each corner on the short walls.

Does this seem reasonable, or do I need the knee braces in addition to the OSB sheets for shear protection? Thanks!

I would assume that some of the answer you require depends on your location. Are you in 'Tornado ally' or just around the corner? Pole size will play into the equation.

lg
no neat sig line

 

[Moose97]

To properly use OSB for shear wall the 16" oc spacing would be required. Also the nailing pattern would be 6"oc around the perimeter and 12" oc in the field.

 

[James-W]

Are you planning on building the pole barn yourself? If you are, that's fine, it's just that I don't think I have ever heard of that done before. Generally speaking, people who want a pole barn will buy it from some company and then have the company send a crew to build it. As for myself, I wouldn't have a clue how to build a pole barn from scratch. A regular stick built structure, not a problem, I can handle it. A pole barn is a different animal altogether.

 

[larry_g]

Are you planning on building the pole barn yourself? If you are, that's fine, it's just that I don't think I have ever heard of that done before. Generally speaking, people who want a pole barn will buy it from some company and then have the company send a crew to build it. As for myself, I wouldn't have a clue how to build a pole barn from scratch. A regular stick built structure, not a problem, I can handle it. A pole barn is a different animal altogether.

James

I think you need to get out more. Lots of members here have built their own, including me.

lg
no neat sig line

 

[matt_i]

Many drawings show the use of knee braces between the posts and bottom chord of the trusses to stiffen the building. Instead, I'd like to place 1/2" OSB panels from the skirt board to the tops of the inside wall for a distance of 16' from each corner on the 48' wall, and 10' from each corner on the short walls.

If I am understanding/visualizing correctly, I think that this is apples and oranges.

Assuming one truss set every 8 feet on top of a post, for the triangulation to work properly, it has to have a very solid pin/nail at the corner/intersection of the top of the post and the bearing area of the truss. Toenails, I guess, but that's not much pinning there as compared to the moment one gets from trying to spade out 4ft of earth as a pole would attempt to tip over. Framing screws would be tough to drive in the haunch area of the truss.Helpful for sure, seems like a good practice but might be a purposeful leftover framing member from setting the truss high atop two poles and wanting it to stay and not tip over.

You could definitely get some shear diaphragm from plywooding the endwalls, or the sidewalls for that matter. But, to get the full effect, you'd need to nail the entire perimeter solid as above. The horizontal purlins stick 1.5" proud of the plane of the posts' outside skins, so I think there would be the extra step of putting in vertical fillers so the nail works more in shear and not just bending the thin shaft over 1.5" of air.

Then nails, #10s are 3" but 2" of that will be taken up by ply and then purlin/filler leaving only 1" of penetration into the posts (on the ends). So I'd use #16s on those ends. But to nail the purlins horizontally would need a shorter 1-1/2" to 2" nail to avoid having jagged teeth sticking thru all over.

TL;DR...I think you could probably take out the diagonal braces at the end if you didn't like the look and had completed sheeting the roof. Picking up shear is definitely possible but requires some detailed thinking.

 

[James-W]

James

I think you need to get out more. Lots of members here have built their own, including me.

lg
no neat sig line

You could be right, maybe I do need to get out more and get in touch with the real world. It's just that every time I see a pole barn going up, I notice trucks with lettering on the side (obviously company trucks) and I automatically figure it is being built by the company that sold the customer the pole barn.

How did you get everything straight when you built your pole barn? When I built my garage the concrete guys made the foundation, floor and stem wall straight and level. I just built the garage on top of it. Pretty simple to do once the concrete work is all done and done correctly. But with a pole barn you don't normally have the concrete work done first so that you have a "straight edge" to work off of. You need to get everything perfectly square and straight and everything needs to be aligned so the walls are straight. That must be a bit of a challenge in itself. I commend you on being able to do all that yourself. I have serious doubts I could do that and get it right.

 

[mattradk]

I'm in upstate NY, so tornados are not an issue. I figured OSB would work with 2'OC girts because OSB is used in residential structure for shear even when construction is with 2x6's 2'OC. The posts will be 8x8 by the way, so the girts will be 2x8.

 

[jack stand]

They make a "t" shaped brace that fit's in a saw cut to make for an easy diag. brace. No compressive strength so you'll need to either "X" them between posts or run them opposite in alternating bay's. This with your OSB & 4' of post in the ground will prolly be overkill.http://www.bing.com/images/search/?...E5A6D756FDFAA98E294CB92E370116D1D&FORM=BRQONH