Barn loft support and interior room framing questions

[petebert]

I'm wanting to do two things in my pole barn. Extend the loft and build a room inside of it. I'm looking for ideas on how to do this and to see if there's anything I should be doing differently. There is currently a loft down the middle. The barn is built on 6x6s, in the middle of the barn they are 10' apart, along the exterior walls they are 8' apart. For the original loft the builders nailed a 2x10x10 beam onto each side of the posts. The joists are also 2x10s, they were set on top of the beams 16" OC and toed in. The floor is 1/2" sheathing.

I've already added the joists for the extension. I toed into both exterior beams and nailed into the existing joists where the two overlap. It was recommended to me that I add bearing blocks under the beams since right now it's just nails holding all that weight. So that's what I'm working on before I go any further. Below is a pic showing what I have going on so far, you can see the new joists going to the exterior wall and a bearing block in place. The bearing block is currently just nailed in place in case I need to remove it and go a different direction, when I am sure they're staying I'll be putting 1/2" bolts through them.

So lets start with the floor, 20 wide by 40 long, 800 sq ft. Lets says I put 500 bales of hay up there, that's 25,000lbs or 31.25 psf, will this be able to hold that? Ignore those random 2x4s attached to the beam, they're part of a chicken pen that's coming down.

I also want to build an interior room, pretty much in place of where the chicken pen currently sits. I'm just not sure how to frame it, I'm assuming I wouldn't frame it like a wall for a house because even pressure treated I wouldn't think I could sit a bottom plate right on the dirt, plus it wouldn't really be secured to anything. I'd like it to be a fully enclosed room with a sliding barn door. I also don't want to add extra stress onto the loft beams. The picture below shows where I'd like the room to extend out to, it's aligned with an exterior post. Should I put another 6x6 post down to create the rooms corner? This could also add extra support to at least those two beams that it would be attached to. The orange line shows where I want the wall to go to. Should I build it like a horse stall and just run the boards all the way to the top?

This shows the entire area I'd like the room to be. Red line on the right shows the post I'd like to line that all up with, red circle on the left is the area for the other wall.

 

[GLyford]

Looks like you'd have to do like a lot of the guys building walls in houses with trusses do, rely on the floor to support the walls, and have a flex connection at the top to keep things sort of in line but allow for differential movement. If you're not running sheetrock over the gap where they meet it's pretty easy. If you are, then you stayrt having to play games like stop nailing the ceiling some distance away sothat at the corner it rests on the wall rock and lets the ceiling frame above move where it wants. Or if there will be a wall going up the side of the loft, there is some sort of expansion channel you can use where the surfaces meet so regular rock won't crack.

But I think no matter how you slice it, you're going to have to come up with a way to support your wall system off the floor: footings or piers and a wooden floor, a slab, something. Maybe one of the contractors on the list can give you a more refined idea here....

 

[truckdiagnostics]

Well it sounds like the lofts weight is supported by the exterior poles, which is a no no unless they are designed for it. I am doing just what you are doing, going to pour a grade beam and have the loft supported all the way down to the concrete slab. Its almost a building inside a building. The room your building inside has to beable to move when the ground freezes the slab can heave, pushing on your pole building. Seen guys pour concrete inside there pole building not being careful and have it grab onto the poles when it freezes. You can turn a building into junk real fast if your not careful

 

[truckdiagnostics]

Well it sounds like the lofts weight is supported by the exterior poles, which is a no no unless they are designed for it. I am doing just what you are doing, going to pour a grade beam and have the loft supported all the way down to the concrete slab. Its almost a building inside a building. The room your building inside has to beable to move when the ground freezes the slab can heave, pushing on your pole building. Seen guys pour concrete inside there pole building not being careful and have it grab onto the poles when it freezes. You can turn abbuilding into junk real fast if your not careful

 

[TnAndy]

Simply nailing beams to the side of posts is extremely poor construction, although done a lot. As you've noted, you need to take steps to correct it.

Somehow some folks don't get that 'post and beam' means the beam sits ON the post, not scabbed in with a few nails that can shear or pull out. Start looking at catastrophic deck failures, and you'll see this a lot.

As to framing an inside room:

1. Yes, use more 6x6 for corners.....but cut a couple of 2x8 or 2x10 blocks to go under the double beam, then run the 6x6's under the blocks so they support the beam (post and beam).

2. For the walls, either dig out and pour a small footer to attach the wall to at the bottom....it doesn't need to be much, as it is basically only bearing the weight of the wall itself...so I'd be fine with a 6"x6" footer with a few bolts cast in it for the bottom plate.

OR

You could notch the corner 6x6's in about an inch deep x 5 1/2" high (finished 6x6), and run a 6x6 from one post to the other at ground level notch to notch. That gives you a bottom 'footer' of wood to tie the wall into. Run a couple long 'timber lock' hex head screws into the other side of the vertical 6x6 to hold the horizontal one in place.

 

[petebert]

I had actually been thinking about what you listed for option 1 yesterday. I sat and stared at it a while trying to figure out how I'd even fit a new post into existing construction and that seemed like the best option. I'm trying to figure out how all the pieces get attached to each other. My guess is, nail 2x10 #1 to existing beams, attach 2x10 #2 to top of 6x6, nails okay there? Wedge into place, nail 2x10 1 and 2 together.

The room I'm wanting to build, at least to start out is going to be a dairy milking room. It ups the price a bit but I really like the horse stall style look. Could I put in a 3rd vertical 6x6, between the existing and the new corner one we've been discussing. It could either be standalone or I attach it the joist above it, then run 2" boards for a wall or 2x6 tongue and groove for a wall with a couple pressure treated boards at the bottom.

 

[Egon]

You may be in need of some onsite knowledgeable advice/inspection if there is weight going on that floor!

Might also look at some building codes and design criteria.

 

[LD1]

Too much missing info to tell weather the loft will hold ~35PSF live load of hay or not.


We know post spacing.......8', with a pair of poorly connected 2x10's for a beam that you are working on making the connection better on.....check.

We know 2x10 joists at 16" OC......check.

How far are the joists spanning? From the exterior wall to the double 2x10 beam?

How are the joists connected on the exterior wall side?

The joists other joists sitting on top of that beam, and coming towards us in the picture.....how far are they spanning? What are they connected to?

Joist sizing and spans is easy......there are tables for that.

For the header/beam......you basically gotta break it down to PLF (pounds per lineal foot). So each joist sitting on top of it, is carrying the load of that joist half way to the next connection.

IE; If both joists (going to each side of that center beam) span 10' till their next support. Each joist is supporting 5' of floor ON EACH SIDE of that carry beam. So the beam, is essentially carrying 10' width of flooring. So thats 10 sq ft for each lineal foot. You need to design for 50PSF would cover the hay, dead load, and some margin of safety. So in that scenerio, you would need a beam capable of 500PLF at a span of 10' between posts.

Well.......A 2 ply 2x10 spanning 10' (between your posts) is only good for 219 PLF. That dont support many sq ft of flooring with a 50PSF load. Bout 2-2.5' of floor on either side. Which means your joist spans would only be ~4-5'. And they sure look longer than that.

Me think your beam is grossly undersized. But simply shortening the span (by adding more posts).....if you had a post every 6'.....you could support 600+ PLF on the beam.

Again, need lots more info to make an accurate suggestion. As of fight now, we have no idea how much flooring is being supported by the beam, how much by the walls, etc.

 

[petebert]

Will this crude drawing help? It's essentially 10' between all posts, except the exterior wall, 8' between those. Red lines represent the exterior walls. The beams are 2x12's, one nailed on each side of the posts, represented by the yellow lines. The joists coming towards us are sitting on top of and toed into the exterior wall beams, on the side closest to us they are nailed into the center alley joists.

 

[LD1]

That helps.

So if you can follow along.....

Your 2- ply 2x12 beam has to support 5' of floor on each side of it. Or 10' total.

So...each foot of that beam has to support 10 sq ft of flooring.

With your estimate of hay at 31psf and change....then you got the weight of the flooring and joists themselves.....perhaps you could get by with 40psf, but 50 psf is a safer margin

2-ply 2x12 over 10' is only good for 303plf. Which would make the floors max capacity 30.3 PSF, and that includes flooring and joist weight. Thats assuming at least #2 SYP lumber too.

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.

2x10 joists are more than sufficient. could have even been more than adequite with 2x8's only spanning 10'. And 2x6's would have almost worked (good for 9'6" span with 50psf).

But that post connection, as others mentioned, is real critical also. Same deal with the beams. That post connection has to support 5' of beam on each side of it. 10' total. And the beam supports 10' of flooring.

So a middle post is supporting 10' x 10' of flooring. At 50 psf thats 5000#. And rule of thumb is 100# of shear per 16d nail so that would mean the 2x12 to post connection + your ledger board under it, would need 50 nails.

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.

 

[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?