Truss/Column Spacing on Pole Barn

[jumbinidaho]

Looking to build a 16'x48'x10' pole barn this summer. Truss pricing ends up being about the same for 8' vs. 12' OC spacing. Going to put in bookshelf girts, and planning on putting a lid on the interior and doing blown in cellulose in the ceiling, 1" spray foam in the walls and then cut and cobbling foam (I have a lot left over from another project), plywood or OSB on the interior walls. 12' Spacing reduces my columns by 1/3rd, which would be $600 on this project, but other than that I can't think of any real differences. Any reason to go with one over the other?

 

[jack stand]

You'll spend more for the fill in framing as it will have to be bigger in dimension and length, but you're add less posts.
I'm a fan of 8' for strength in more ways than one.

 

[strutaeng]

Your purlins will be larger/heavier for the longer spacing. I'm assuming dimensional wood for purlins? 24" O.C. spacing?

Edit: meant roof purlins, NOT girts.

 

[jumbinidaho]

Your girts will be larger/heavier for the longer spacing. I'm assuming dimensional wood for girts? 24" O.C. spacing?

Yah, exactly.

 

[jumbinidaho]

You'll spend more for the fill in framing as it will have to be bigger in dimension and length, but you're add less posts.
I'm a fan of 8' for strength in more ways than one.

Yah i'm leaning toward 8' for ease of building it myself but wasn't sure if there were other things to consider.

 

[billconner]

I like the 12' spacing with double trusses at each column line. No headers (except at doors). Fewer pieces/connections will be faster. 2x6 bookshelf girts. Just seems like a more logical system. Hansen Buildings has worked this out very well.

 

[jumbinidaho]

I like the 12' spacing with double trusses at each column line. No headers (except at doors). Fewer pieces/connections will be faster. 2x6 bookshelf girts. Just seems like a more logical system. Hansen Buildings has worked this out very well.

Double trusses raise the cost substantilly, but local truss company send me single trusses that will work they said for 12' OC. Why does 12 vs 8 spacing change headers for windows? Thanks

 

[billconner]

No truss carriers with trusses just at posts - but indeed that is not a 8 vs 12 issue. Didn't know you were doing trusses just at posts. Good concept IMHO.

If your truss guy can do a single truss that works at 12' on center, good.

 

[Shoester]

Here in KS most builders I’ve talked to have highly recommended 4’ spacing on trusses and 8’ spacing on posts.

 

[PWC Repair]

About 9 or 10 years ago we had about 2 inches of sleet and then 8-10 inches of snow. It's NOT standard winter weather for us......most every barn with 10ft (or more) spacing came down.....including the HVAC supply house I worked at. So did several boat docks.....chicken houses, etc.

 

[jumbinidaho]

About 9 or 10 years ago we had about 2 inches of sleet and then 8-10 inches of snow. It's NOT standard winter weather for us......most every barn with 10ft (or more) spacing came down.....including the HVAC supply house I worked at. So did several boat docks.....chicken houses, etc.

Not really sure what to make of these anecdotes. I had a 12' OC spacing building quoted by a national kit supplier...thats an engineered building for my area in 85lb snow load. Sounds like you guys never get snow and everyone built as if you'd never get it and then you got snow and all the improperly built buildings collapsed?

 

[rayra]

Typically in multiples of 8' for reasons. Rest of the lumber, sheeting / sheathing etc.

 

[jumbinidaho]

Typically in multiples of 8' for reasons. Rest of the lumber, sheeting / sheathing etc.

You can actually get lumber in 2' increments from 8' quite easily, and my lumber yard stocks most of them (except 14' for some reason). Most sheathing, sheeting, etc. doesn't typically span more than 2' anyways, so you're going to be putting purlins, rafters, whatever to fill in whether it's 8' or 12'.

 

[BearyNelson]

My "kit"
Is for 12 foot bays, two trusses set on either side of each interior post. I like it. I've poked around a lot of pole barns built around here in lead up to my build and most are built this way with either 10ft or 12ft bays. I'm in north idaho so the snow is no joke.

 

[PWC Repair]

Not really sure what to make of these anecdotes. I had a 12' OC spacing building quoted by a national kit supplier...thats an engineered building for my area in 85lb snow load. Sounds like you guys never get snow and everyone built as if you'd never get it and then you got snow and all the improperly built buildings collapsed?

Yes, don't get much snow. Most everything around here gets spec'd for like 20# snow load and we exceeded that. My point I guess is to go ahead and overbuild so you can sleep at night.

 

[jumbinidaho]

Yes, don't get much snow. Most everything around here gets spec'd for like 20# snow load and we exceeded that. My point I guess is to go ahead and overbuild so you can sleep at night.

Yah that's for sure, I tend to be on the overbuilt side as I get kind of paranoid. I'm probably going to pay for an engineer even though my inspector is very relaxed and doesn't care.

 

[Spud McGee]

I went with 12' between some of my posts to allow for a wider roll up door. 8' on center gives you enough room for a 6' roll up door. May as well be a man door at that point.

Worth mentioning that you dont need to all be uniform. Some of my posts are 5' apart, some are 10', and some are 12'.

 

[WNYflyer]

In my area you would be probably be hard pressed to find an engineer to design a homeowner supplied and erected pole barn type structure and if you did it would probably be one of the guys I wouldn't trust to design my doghouse not to mention the potential additional cost.

 

[jumbinidaho]

In my area you would be probably be hard pressed to find an engineer to design a homeowner supplied and erected pole barn type structure and if you did it would probably be one of the guys I wouldn't trust to design my doghouse not to mention the potential additional cost.

I've seen some of your posts in other threads and you seem to have a good handle on the engineering aspects. Truss company can build me single trusses spanning 16' on 12' spaced columns, they said its not a problem (i'm in fairly high snow load, 85lb). I'm thinking of doing on edge 2x6 purlins on 2' spacing flush mounted to top of truss with hangers between the trusses and then the same thing for the ceiling between the truss bottom cord. One thing I am wondering is - the only info I can seem to find on this method is from hansen building, and they use double trusses. Will nailing hangers on opposite sides of a single truss directly in line with each other be a problem? Seems like that would be a problem with the nails pushing against each other.

 

[billconner]

2x6 - 12' span - does that work for a roof load? 85 LL + 10 DL is 2280 pounds per purlin.

Correct that - not 2280 - somewhat less because of slope and projected plan area - so maybe 1500. But still seems beyond 2x6.

 

[3pedal]

I bought a place with the building already there. It has 12' on center posts and double ply trusses. Still have headers for the garage doors, as they are 18' wide. The advantage to the wider spacing is more flexible positioning of my lift. With ~12 ' walls, I set up my 4 post to sometimes have something above the bottom cord of the truss.