What size beam to use for 16' doors on polebarn?

[johnday]

Re: What size beam to use for 16\' doors on polebarn?

plumboy;I think I'm seeing what your saying a little clearer. Yes, by letting in the LVL it would be stronger than the bolt. Are you saying you would then use 2X6 for a face board? That would maintain the plane in line with your girts. After talking with the building dept., you will most likely to have to still double that LVL. I think if you use the 3X3 angle and bolt like I said, you should be good to go.

You installed the posts like I do except for the depth and pouring redimix around the pole. That bag of redimix in the bottom becomes a footer. I don't know what your frost line is in your area, but up here I have to go down a minmum of 42".

Another trick in building a house or garage for window/door headers, is to use that 1 3/4"X 11 1/4" LVL. That way you don't have to screw around cutting those rotten little cripple studs. A little overkill and few more $, but it sure saves labor and you wind up with almost a bomb proof header above doors. Gauranteed that header ain't gonna sag! /forums/images/graemlins/grin.gif

 

[plumboy]

Re: What size beam to use for 16\' doors on polebarn?

The 2x6's would go under the lvl's.I would still continue the outside 2x12 band around the top.I think I should have said I am planing on putting this where the 2x12 band runs at top.The lvl will be flush with the posts top giving me the most I can get for an opening.As for the frost line I know for footers they need to be 18" deep for building code and my water services have to be 30" deep.John and all thanks for the input.

 

[rambler]

Re: What size beam to use for 16\' doors on polebarn?

Posts go a lot deeper here in Minnesota, 4' at least. Not sure 3' was deep enough. At least you put a foot on it.

This would have been so much simpler with doors in the gable ends, maybe you don't get snow there, but here you end up with a 3-4' pile of snow in front of the door after every snowfall, & snow melt dripping on you every day. You can put a taller door in the endwall, with a roll up door you lose 3' on a sidewall, with a slider you lose the foot+ of the header - all wasted ceiling space now.

Dad made the same mistake on a 30x50 machine shed here, what a miserable building. I've spent 3 days chopping ice out of the door track after ice storms, finally the last 3 years just leave a door open over winter. I need to get to the tractors for the livestock, nothing else to do.

Never, never again will a door go in a sidewall here. Terrible construction.

--->Paul

 

[plumboy]

Re: What size beam to use for 16\' doors on polebarn?

4"-6" of snow is big here,but I guess 12" is not out of the question.The barn fit perfectly between my other barn and fence,but the other way I would of ran into some pad building.I am going to put a 16' deep shed that runs the eve when I'm done so you will actually be under roof entering and exiting the doors.

 

[johnday]

Re: What size beam to use for 16\' doors on polebarn?

plumboy; Sounds like you planned ahead with that overhang, that's a real good way to keep everthing almost snow free. And the best part is no rain dripping on your head. How high is your ceiling going to be ? /forums/images/graemlins/grin.gif

 

[plumboy]

Re: What size beam to use for 16\' doors on polebarn?

The eve should be about 12 1/2'.Going out the doors the land drops about a 1 1/2' to some swells.I'll have to biuld up a little with gravel but I want no less than 11 1/2' eve on the sheds even if I have to cut it down to 12' deep.

 

[johnday]

Re: What size beam to use for 16\' doors on polebarn?

plumboy; That's going to be great. You won't even have to fold your ROPS down. Right now, I just barely make it in the garage with the ROPS folded. Those 7' doors just don't make it. My polebuilding I'm planning will have to have at least 9' high doors, with a 10' ceiling minmum. Up where that is going they get real snowstorms and feet and not inches of snow at a time. Really can't wait to be there year round. /forums/images/graemlins/grin.gif

 

[bugstruck]

Re: What size beam to use for 16\' doors on polebarn?

Read thru this pretty hastily but here it is. Keep in mind I'm not a structural engineer but have sized many beams when the structural guys were struggling with wood loads, spans, and sizes. Most are a little weak in the wood area but real strong in steel and concrete.

If your snow load is 20 lbs. per square foot you need minimum (2) 1 3/4" x 11 7/8" beams. They are dsigned to be connected tight togeather and fastened to each other according to manufacturers instructions. As soon as you separate them to each side of the post without full solid wood infill these caculations are out the window. Technically you are point loading (in lieu of uniformly distributing the load) this beam with 8' truss centers and really should have a structural engineer certify the design. If your snow load is 30 lbs./SF you need (2) 1 3/4" x 14" beams. Same rules apply of course. If I were point loading this opening with a truss load near mid span I'd up this to (3) 14" beams or (2) 16" beams.

Keep in mind that these values are based on gang lam LVL beams that are 3100 Fb-2.0E which are commonly available. Different beam grades require different sizing.

As for the footers I'd guess your soil bearing capacity at just over 3,000 lbs per SF. You are loading either 5,600 lbs at each post or 4,000 lbs. at each post depending on a 30 or 20 lbs. snow load. Your soil could have much higher values than the 3,000 lbs. I reference. Even if you have the footers undersized you should get fairly even settlement rates on this structure and be OK. 30" down should be adequate for your area. Believe it or not the depth is more of an uplift issue in high winds if your frost line is less than 30". May be a little short there but still passable probably.

As for the 8' truss centers and 2 x 4 L- shaped purlins. Hope the trusses are designed for that spacing??? 2 x 4 purlins are inadequate even in L- shaped configuration. I'd guess 2 x 6 would be more like it.

If I were in your shoes I'd pull an engineer in.

Hope this helps (in the end). /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

Good Luck

 

[plumboy]

Re: What size beam to use for 16\' doors on polebarn?

Thanks bugstruck.The trusses are designed for 8' centers and there are going to be 2x6's between the trusses sticking up an 1 1/2" so the 2x4 will nail into it.I need to find out our snowload around here.

 

[bugstruck]

Re: What size beam to use for 16\' doors on polebarn?

Plumboy, you have the structure end figured out now. That is one nice size building. More work than many would think, I know. Well worth the effort though. I'm looking forward to doing mine in the next year or so. Hope the New Year treats you well. Send us a photo when you get it done. /forums/images/graemlins/grin.gif

Enjoy,