Barn loft support and interior room framing questions

[ultrarunner]

I love threads like this... always a lot to learn.

Thanks LD1

 

[petebert]

Couple of options is you could either add a 2x12.....or add a 2x10 to EACH side. So 3 2x12's....or 2 2x12'x and 2 2x10'x.

And IIRC, 1/2" bolts are only good to ~250#. So as you can see, its gonna take more than just a few bolts and some nails. You should really consider notching the tops of the posts, and letting the board sit on the post. That eliminates fastener shear as a consideration, all the fastener has to do is hold the beam ontop of the post, but the weight is all transferred directly to the 6x6.

Notching the posts at this point would be quite a bit of labor since there's already an entire loft sitting up there. But your saying I could just run an additional 2x12 the length of the beam on one side. Then there's the matter of holding the entire structure up. What about putting an additional post right next to the existing post so the now sandwiched beams are sitting on top of the new post?

 

[LD1]

That would work as long as it has a solid bottom/footer.

Remember, the post is supporting 5000#. If you just set a 6x6 on dirt and put 5000# on top, it would sink over time

 

[petebert]

And does only the middle row of posts need the extra beam since that one is supporting weight both directions?

 

[LD1]

I'd at least run a 2x6 all the way to the ground and nailed to the 6x6 to bear the load

 

[petebert]

Thanks for the help. So to summarize to see if I have this right.

Because the middle row covers a 10' span it needs a 3rd 2x12. It also needs something to support the beams aside from nails, like another post with a good footing. Do I attach the posts to each other and does the 2nd post go in the ground 4' like a standard post in Michigan or is it up higher with the footing?

The outer rows only cover a 5' span so they just need something other than nails holding the beams up, so they get a 2x6 down to the ground.

 

[LD1]

There are many ways to skin the cat. You just have to analyze all the facets and make sure they can handle the load.

But also keep in mind, different grades and species of lumber have an effect. For example, a pair of 2x12's spanning 10'....

If #1 SYP would carry 405plf. Given your 10' joists....that would equate to a 40.5 PSF total floor load.....
If #2 SYP You loose 100plf capacity, and thus only a 30 psf floor rating
If #3 SYP TAkes you all the way down to 180 PLF or 18 PSF floot. And even a 4-ply of #3's is on good for a 40 psf floor.

As to the exterior wall...yes, it only supports 5' of the floor.....so each foor of the carry beam only needs to be good to 250#.
AND, the beam is spanning a shorter distance. The result:
A pair of 2x12's at an 8' span if #2's is good to 474 PLF. Well over the 250 needed.
Even a pair of #3's over 8' is good for 284plf.

So yea, the exterior beam is good. BUT, at 250PLF, and 8' span......the post to beam connection has to support 2240#, OR 1120 per 2x12. So you would need about 11 nails each.

But what size are the footings since you used exterior posts designed to support the rest of the structure? Can the footing support an extra ton of weight? Footer sizing is usually based on soil type, and anticipated snow loading, etc.

As to the interior posts.....Yes if you put another post in, I would dig down to the footing. But I really dont think it would be that hard to notch the post. Remove the 2x12's one at a time. (a single 2x12 should support an empty floor above). Notch the post, put 2x12 back and toe nail joists. Repeat on other side.

 

[ajmaxham]

Can you add the extra 6x6 in the center of the 10' span? That way you can notch the 6x6 for support and reduce the span from 10' to 5'. Put the center post 4' in the ground with a good footing (24''x24''x8'').

 

[truckdiagnostics]

That would work as long as it has a solid bottom/footer.

Remember, the post is supporting 5000#. If you just set a 6x6 on dirt and put 5000# on top, it would sink over time

Around here anyway once the clay under post gets soft into the ground it goes. That would be my concern. The guy that helped me build my pole building. He does it on the side and he can keep himself busy just fixing pole building. If you are not 100% sure those poles are designed for the load and chances are they are not. You need to support the loft to the slab, and cut it loose from the poles! Then the center poles need to go too the same monolithic slab, so that it can move independent of the surrounding building.

 

[GLyford]

If this is going to be a milking parlor, are you going to have to build it all to be wash-down rated?