Building an "old fashioned appearance" new barn

[schweizer]

I'll post more pics of the land and views eventually.

I have a couple options for "engineering" the loft floor:

1. Support beams lengthwise/North-South (12 ft) and then floor joists horizontally between/East-West (16 ft)
2. Support beams horizontal/E-W (16 ft) and floor joists lengthwise/N-S (12 ft)

Is there a clear winner between either option? See attached drawings. I'll tell you after I get some replies what my reasoning is in favoring one over the other, but I'm not a contractor.

Needs to be engineered for about 3 bales high of hay storage.
By my reckoning that equates to about 60 psi live load or 70 psi total load.
16' x 24' loft = 384 ft2
384 ft2 x 70 psi = 26,880 lbs total load max (like I'll ever put that much up there!)

Thanks.
Marcus

 

[Darrenone]

I would think 16' is a long span for floor joyce without any middle support. To get the max load capacity I think your floor joyce needs to be the 12' way. Are they going to sit on top of the beam or are you using hangers? As far as those load calculations, I don't think you can build it to hold any where near that much weight. But I'm no engineer.

 

[Iplayfarmer]

I'd also suggest you go with the 12' span for your joists. Shorter span = more load bearing capacity.

There are a few good joist span calculators out there that will help you know what kind of load you can put on a given size of joist with a given span. If in doubt, overbuild. The extra few dollars for a deeper joist will likely pay off later in less sag and a more stable floor.

 

[schweizer]

No, hangers would never handle that load. I'm going to through-bolt 2x6's to the side of the posts and set the beams on those. (Common on pole barns.) LVL's (or gluelams) could handle the loads either direction I pick. BCI's (wood I-joists) or 2x12's can handle the 16' span easily enough if I go with 12' for the beams/LVL's in the opposite direction.

edit: Ooops! @Darrenone, sorry, I misread your post. Yes, hangers are an option for the joists, but not for the beams. I'm trying to keep 10' ceiling clearance underneath for the tractor and backhoe, so if the joists sat on top of the beams I'd lose some clearance.

 

[schweizer]

Here are some of the load tables I've been using:


For floor joists w/ regular lumber (web link)

For glulam's (PDF)

Timber beams - load tables (PDF)


If the beams span 16' East-West, there are 3 beams. The center beam will need to carry 1/2 load and the other 2 will each carry 1/4 load.

If the beams span 12' North-South, there are 4 beams. Each beam will carry 1/4 of the total load.

(i.e. 26880/4 = 6720 lbs --> 560 lbs/lineal foot for the 12' direction at 1/4 of the load per beam)

 

[Groo]

I'd do 2 long beams, and a bunch of shorter joists.

 

[ultrarunner]

Steeldust built something similar a few years ago and posted lots of pictures...

http://www.tractorbynet.com/forums/projects/110718-want-see-yet-another-pole.html#post1310013

 

[schweizer]

Yes, steeldust built a beautiful barn. I commented on it near the end of his thread. Got some ideas from him.

 

[jimmysisson]

If you imagine the upper rafters pushing out horizontally on the beams, spreading them apart, that's what you're trying to contain. If your floor beams run between the posts (is that east-west in your building?), then the major requirement is that connection between the floor beams and the posts. Strap steel wrapped around the post and bolted along the beam would be secure.
Next connection is the top girt at the post tops. The roof load pushes the girt out and the post tries to stop that push. That post-girt connection has to resist the push. Plywood on the shed roofs will help resist the push as well, though if you're going for the classic look you may not want to see it when you look up. You also need to be sure the upper rafters are well pinned to the top girt.
In reality, the thing is not going to fall down. It's just that nagging disappointment a couple of years after you're done and the sag starts to become evident. That's also a reason to figure your loads at 100#/sf, just to be sure. It won't take too long to forget the extra cash the big joists cost, compared to being irritated by the sag.
Keep up the blow-by-blow.
Jim

 

[schweizer]

Thanks for the responses. In the end, running the floor support timbers (6x12 microlams) north-south on the short span, and running the BCI floor joists across the longer 16' span won out. Contractors I spoke to didn't think it would matter either way because the floor diaphragm would hold the posts from spreading any. They thought building w/ BCI's would be better than 2x12's for floor joists and it priced out similarly.

Today is a long day at work, but yesterday was a big work-outside day. *Lots* of tractor time. I wanted base rock under the barn and around the perimeter and the guy I contracted to bring it was supposed to bring 60 yards of 4"-minus and drain rock for the French drain. Well, when his drivers arrived w/ tandem trailers, they had 4" *clean* rock, not 4" *minus*. That means I had spend a bit more time than expected spreading out that stuff, then I had to order 20 yards of decomposed granite to spread over top. Part of that was spread by hand. Now the rock around the perimeter is real rough still. After talking to the contractor this morning, he's going to give me a discount on 3/4" minus to spread over top.

The material for the barn was delivered a few days ago. Hopefully I'll start setting loft beams this weekend. Since I know you all like to know how much things cost, I'm including a materials list (text format). Aim was for around $10,000 but I'm over that now, but the metal roof and installation is the main expense remaining. Just my labor on everything else...

Marcus

Materials List w/ Running Total (Sorry, formatting is not coming out right, will fix later.)