Loft build in metal building question

[biggziff]

I'm adding an 8X20, 72" to bottom of joists, loft in our metal shed. I've anchored a ledger to the building, but am trying to figure out a way to support the front rim band with as little obstruction to the space as possible. I will have at least 6 4X4 posts around the perimeter of the platform so that it is basically self supporting (not relying on the steel building for support). I can take the easy route and drop a 4X4 at the front center of the rim band, but I'd like to have the space under this loft as open as possible. We park multiple items here (zero turn, JD X590, Ventrac, snowblower, etc.). We will be storing plastic totes with relatively lightweight items on the loft floor. Beekeeping equipment, my wife's landscape decorations, shovels, rakes, etc. Probably less than 500 pounds total.

I'm looking for suggestions on how to keep the space as clear as possible, but still support the loft adequately. I'v considered using cables to the rafters, diagonal bracing off the rear wall, laminated beam at the rim band and simply putting a 4X4 under a doubled, center joist.

Thanks in advance.

 

[PCustoms]

What size joist are you spanning the 20' with?

 

[biggziff]

What size joist are you spanning the 20' with?

Undecided. I've been looking at span tables and trying to determine best case. I need other brains to look at this and provide input.

 

[billconner]

My sense is this type of building is engineered to within an inch of its life. No extra structure at all. I wouldn't support anything of the frame.

 

[PCustoms]

My sense is this type of building is engineered to within an inch of its life. No extra structure at all. I wouldn't support anything of the frame.

That's a good point.

You should add some 4x4 posts along the ledger in the back, and plan for at least one on each end of the rim/band.

 

[biggziff]

My sense is this type of building is engineered to within an inch of its life. No extra structure at all. I wouldn't support anything of the frame.

The stamped plans for this building look a lot better than what you might expect. I did upgrade everything available when I spec'd it for snowload, wind, etc. Yes, it's not a stick built building, but not terrible. I am using 4X4 posts at the corners of the loft and at least one on the rear ledger, so it will be attached to the walls, but also self supporting (mostly)

 

[FL Guy]

My building is like yours.. I’m going to be putting up a loft as well. No way around that 20’ span with wood. Going to need a 6x6 in the middle, unless you get a big I- beam

 

[biggziff]

My building is like yours.. I’m going to be putting up a loft as well. No way around that 20’ span with wood. Going to need a 6x6 in the middle, unless you get a big I- beam

I thought so, but span charts state a 2X12 can span 23' with 40 psi live loads. I just don't think that's going to be the best option. I suppose I could make up a laminated beam with ply center and 2 2X12X20, but again...that seems like more work than necessary.

BTW, an 8' 4X4 can support up to 6000 pounds without additional bracing. Hard to believe, but apparently it's true.

 

[larry_g]

One option that you can use is to put your support posts on the front spaced out 1-2' from the side walls. Now you only have to span 16-18' reducing the length of the support beam. Face it, we all have a bunch of **** leaned up against the walls, work benches or shelving so the loss of that 1-2' to the support post is probably not going to be missed.

lg
no neat sig line

 

[Youngandfree]

You really think those flimsy metal verticals are going to support a bunch of extra weight?

 

[readhead]

Don’t confuse snow load with collateral load which most tube steel gable walls have none. I don’t see a problem with attaching a ledger to the end wall columns but I would suggest that some sort of post be attached at each column to direct the tributary loads to the floor.

 

[billconner]

span charts state a 2X12 can span 23' with 40 psi live loads.

Sure, douglas fir select structural grade 12" on center.

 

[biggziff]

You really think those flimsy metal verticals are going to support a bunch of extra weight?

Show me where I said that. Maybe read the thread instead of being so negative?

 

[biggziff]

Don’t confuse snow load with collateral load which most tube steel gable walls have none. I don’t see a problem with attaching a ledger to the end wall columns but I would suggest that some sort of post be attached at each column to direct the tributary loads to the floor.

I mentioned elsewhere in this thread that I am placing 6 4X4 around the perimeter of the platform so that it is basically self supporting. Just trying to keep the front opening as clear as possible.

 

[dcg9381]

My building is like yours.. I’m going to be putting up a loft as well. No way around that 20’ span with wood. Going to need a 6x6 in the middle, unless you get a big I- beam

Sure you can. An LVL can do 20' all day long.

 

[dante2]

Not mine one of our members though.

My new garage build! 30x50 !

Leaves are falling and finally got to a point where just blowing them off the driveway wasnt good enough. With my wifes business now at our house I have had to step up the lawncare routine to keep it looking nice for her clients. Hard to charge a premium if your facility doesnt look up to par...

www.garagejournal.com

 

[biggziff]

Sure you can. An LVL can do 20' all day long.

That's an option. I spoke with one of the engineers at a local company that makes them. They did a great job with the monster LVLs they made me for our big shop build. This should be a piece of cake, but was trying to keep this as a budget build. Thank you.

 

[biggziff]

Not mine one of our members though.

My new garage build! 30x50 !

Leaves are falling and finally got to a point where just blowing them off the driveway wasnt good enough. With my wifes business now at our house I have had to step up the lawncare routine to keep it looking nice for her clients. Hard to charge a premium if your facility doesnt look up to par...

www.garagejournal.com

That's just about exactly where I'm heading. I may double the center joist and move the post back 3'.

 

[Youngandfree]

Show me where I said that. Maybe read the thread instead of being so neagtive?

I'm not the first person to mention the flimsy building. So get your ******* out of a knot.

 

[biggziff]

I'm not the first person to mention the flimsy building. So get your ******* out of a knot.

Nothing knotted here...people don't read the posts, then make comments that aren't applicable.

 

[mike93lx]

You've attached a ledger to the building... I get that the posts will support the weight, but any lateral load will be placed on the building, which it was absolutely not designed for. I would make this 100% free standing.

A beam in the center with posts front and back will split the joist span in half if you hang them from the sides. Should allows them to be considerably less tall, adding headroom

 

[biggziff]

You've attached a ledger to the building... I get that the posts will support the weight, but any lateral load will be placed on the building, which it was absolutely not designed for. I would make this 100% free standing.

A beam in the center with posts front and back will split the joist span in half if you hang them from the sides. Should allows them to be considerably less tall, adding headroom

Good points.
Joists will run front to back (2X6X8).
I intend to diagonally brace the posts at the back and sides, but this loft will be used to store items and seldom accessed by anyone walking on it, etc. It's an outbuilding used just for storage.

 

[mike93lx]

Good points.
Joists will run front to back (2X6X8).
I intend to diagonally brace the posts at the back and sides, but this loft will be used to store items and seldom accessed by anyone walking on it, etc. It's an outbuilding used just for storage.

Ah I assumed the other direction when you were talking about joist sizing for the full span.

 

[txvwnut]

The upstairs of my shop is 2x8's on 12" centers spanned 20 feet with two layers of 3/4" tongue and groove plywood for decking. For the OP's loft I'd make up a laminated beam or use doubled LVL on the 20' span then run the 2x8's on the 8 foot run. Deck with T&G 3/4" ply and call it good.

 

[biggziff]

Ah I assumed the other direction when you were talking about joist sizing for the full span.

Just the rim joist at the front. Thanks.

 

[mike93lx]

I'd call that a beam since it's carrying the joists. Just different terminology

Just the rim joist at the front. Thanks.

 

[billconner]

I'd call that a beam since it's carrying the joists. Just different terminology

Agree. Really a header in code terms.

Run the other way just 4 posts instead of 6, with short headers either end.

 

[biggziff]

Agree. Really a header in code terms.

Run the other way just 4 posts instead of 6, with short headers either end.

Yep, but I think I'd need to do something in the middle or it would bounce a bit. I already bought all the 8' 2X6 so I'll just run it this way. I have a pile of 4x4 from another project I want to use up anyway. Thanks.

 

[CraigStu]

A typical 16ft garage door header is two 2x12s some w/ plywood in between. Use 20ft 2x12s w/ larry-g's idea of setting it on support posts 2ft from the wall on each side. Easy, inexpensive, and works in millions of garages.

 

[housewolf]

I know I’ll be roasted for this and wasn’t going to post but decided to expose myself anyway since I started with almost the same intention as the OP. Almost everything on my property is or related to a rebuild after a tornado destroyed our house in 2020. Nothing is as I would have done had I started with a blank slate. I had limited/unknown funds to work with in spring 2020 while building costs were escalating daily but needed something up quick to get my “stuff” out of the weather.

I had a slab placed and put up a “flimsy carport type buildimg”. I needed to get lightweight “stuff” off the floor so I’d have room to get everything out of the weather. I was working alone (I’m not a young fella) so my methods had to account for that. I did have a lot of 2x2” square tube. I framed up a perimeter and filled it in with more tubing then decked with 1/2” OSB.

As time went by, I wanted to get rid of the center post and had some heavy 4” channel laying around so I made two columns and a header to get rid of the “post”

Since this last pic was taken, I wanted to remove as much weight as possible from the original structure so I added another header & two more columns from the channel 2/3 of the way back. The whole thing is 18’x8’. I maybe keep 1K#s total up there and do get up there to walk around to get stuff. The lift is functional now, it’s wired and I have conditioned air. It’s evolved into “my shop”. Am I going to die?

 

[dante2]

.

 

[dante2]

I know I’ll be roasted for this and wasn’t going to post but decided to expose myself anyway since I started with almost the same intention as the OP. Almost everything on my property is or related to a rebuild after a tornado destroyed our house in 2020. Nothing is as I would have done had I started with a blank slate. I had limited/unknown funds to work with in spring 2020 while building costs were escalating daily but needed something up quick to get my “stuff” out of the weather.

I had a slab placed and put up a “flimsy carport type buildimg”. I needed to get lightweight “stuff” off the floor so I’d have room to get everything out of the weather. I was working alone (I’m not a young fella) so my methods had to account for that. I did have a lot of 2x2” square tube. I framed up a perimeter and filled it in with more tubing then decked with 1/2” OSB.

As time went by, I wanted to get rid of the center post and had some heavy 4” channel laying around so I made two columns and a header to get rid of the “post”

Since this last pic was taken, I wanted to remove as much weight as possible from the original structure so I added another header & two more columns from the channel 2/3 of the way back. The whole thing is 18’x8’. I maybe keep 1K#s total up there and do get up there to walk around to get stuff. The lift is functional now, it’s wired and I have conditioned air. It’s evolved into “my shop”. Am I going to die?

So let me see if I have this right the rail across the back of the loft is held up by brackets and some self tappers? I don't see any posts supporting the rail but I might have missed them.

 

[housewolf]

So let me see if I have this right the rail across the back of the loft is held up by brackets and some self tappers? I don't see any posts supporting the rail but I might have missed them.

That’s how I held them up there so that I could weld them in place, this was a one man project. I had it like that (welded) a pretty good while until I added another header 18” from the wall, like the one in front.

 

[FL Guy]

That’s how I held them up there so that I could weld them in place, this was a one man project. I had it like that (welded) a pretty good while until I added another header 18” from the wall, like the one in front.

You welded the steel to the building uprights??

 

[housewolf]

You welded the steel to the building uprights??

Yeah

 

[billconner]

Wonder what the snow load is in East Texas. I'm in upstate NY like the OP and it's 60 psf here.

 

[housewolf]

Wonder what the snow load is in East Texas. I'm in upstate NY like the OP and it's 60 psf here.

About this much. That’s my slab about where the fence stops. It’s pretty rare we get any at all. This was a BIG deal. It hasn’t snowed again since the building went up

 

[FL Guy]

Yeah

Yea that’s not good. Then poles are 14 or 16 ga unless you upgraded to 12 ga. You have definitely weakened and made the steel uprights vulnerable.
I would put some 4x4s against the walls, anchor it to the ground and maybe secure the 4x4 to one or two posts. That may not be good also, but it’s alot better than welding. JMO

 

[housewolf]

Yea that’s not good. Then poles are 14 or 16 ga unless you upgraded to 12 ga. You have definitely weakened and made the steel uprights vulnerable.
I would put some 4x4s against the walls, anchor it to the ground and maybe secure the 4x4 to one or two posts. That may not be good also, but it’s alot better than welding. JMO

They are 12g, but that’s pretty thin too. I “upgraded” the uprights and the siding thickness and like I said have gone back and added another header like the one in front. If suddenly the building disappeared, the mezzanine would still be there. It’s totally supported now by 4 columns (4” channel b2b). I’m not bragging on it, in fact the opposite*, and I said in my first post I knew I’d be criticized. It wasn’t engineered and I’m not a steel erector. I have built supports for pretty heavy, 10K#+, equipment and piping though. I’m not “recommending it” but I’m 100% comfortable climbing up there and moving stuff around.

ETA; In my first post I did say this was NOT, a well planned/thought out/funded operation, in fact the opposite, a 911 after a tornado destroyed my home to get my welding machine, boat, tools, plasma cutter, etc… out from under tarps in the yard. (maybe not quite that bad but they were only protected from weather by tarps)

 

[CraigStu]

Housewolf it's been up for 4 years so I suspect it will be OK.