Maximum practical height for pole barn?

[NC357]

I recently bought some land and I plan on building two buildings there - a smaller storage building, and a very large shop/house. I used to have a big old wooden barn that was 3 stories high inside, I loved that. It kept the heat up high and gave me limitless room to work with. Also made for a great 3 story mezzanine. Unfortunately like most old barns, it had giant timbers and posts all over the place getting in the way.

Anyway, I'd like to replicate a BIG OLD barn, but with modern materials and mostly free span inside. At this time I am thinking wood poles, metal roof, and wood siding. Probably use steel roof trusses for something around 60x120.

My question is, what is the tallest practical eave height for a wood pole barn like this? I know I need to talk to an engineer, and I know I could build it 100 feet tall if I spent enough money. I'm wondering, what is practical using wood poles?

I'm thinking I would probably use laminated posts (8x8?) on something like perma-columns to reduce the length of the poles needed.

I am in Northern North Carolina, we don't get a lot of wind but the occasional hurricane or tornado can come through. I would imagine the wind load on a 120' wall is one of the biggest limiting factors.

 

[iagsxr]

My brother's farm shop has 18' tall doors so he can get combines with tank extensions inside. Wall height must be in the 20'-22' range. His shop is 60' × 120'. He also has just a storage building similar height that's 80' × 200'.

They're both pole construction, laminated poles. I think his poles are at least 10"×8". They're massive compared to the poles in my 14' tall building.

 

[matt_i]

A red iron or structural steel building might come into play here.

The plant where I work has 12" box tube steel columns with a 5/8" wall on 50' centers. Approx 35 feet tall. Not a gambrel roof, its a low pitch bar-joist affair.

The advantage of the steel is it will never rot, and I find the longer the timbers I buy, the more curvy they tend to be. Having to fight with super-long expensive timbers way up in the sky is not my idea of fun. You mentioned a 3 level mezz, the concrete foundation would be much more forgiving of large(r) column loads than a post set on a cookie in my opinion. Obviously you could pour more massive pads in the bottom of the holes to decrease ground -pressure.

 

[NC357]

A red iron or structural steel building might come into play here.

The plant where I work has 12" box tube steel columns with a 5/8" wall on 50' centers. Approx 35 feet tall. Not a gambrel roof, its a low pitch bar-joist affair.

I might have to go that way, but for some reason I really like using wood. 50 foot centers would sure be nice though. I don't want a gambrel roof but I do want a steep pitch like an old barn. I do want steel trusses because of the open space they provide compared to wood.

For the mezzanine I would like to have a full 8' of head room on two floors, with a third floor being taller in the middle. The mezzanine will most likely be free standing, and structurally separate from the main building. (and built a little bit at a time) I would make sure there is extra concrete under where ever I want posts.

That all adds up to about 23 ish foot minimum height for what I really want. 25 foot would make me really happy...

I definitely would not expect to find a straight wood pole that long, it would have to be laminated.

 

[StevenMorgan]

A custom steel building will likely be chaeapest. Thinking about three levels and a steep roof just sounds like a lot of truss work for anything other than steel. With a red iron building, you could specify whatever length, width, and individual floor heights, along with roof pitch, and get a completely clear floor plan without any extra posts.

If you do the same thing out of wood, I think the cost of engineered framing would be worse than the steel.

 

[PAToyota]

I might have to go that way, but for some reason I really like using wood. 50 foot centers would sure be nice though. I don't want a gambrel roof but I do want a steep pitch like an old barn. I do want steel trusses because of the open space they provide compared to wood.

If you’re going steel trusses, I’m not sure why you’d want wood columns. The practical height issue is going to be on the lateral loads on the columns. Particularly with wide spans, those lateral loads will be increasing exponentially. At some point, you’re going to be trying to resist pulling the laminated columns apart more than you’re supporting loads.

 

[rburke65]

No experience here but, that tall of a build I'd be inclined to think steel myself.

 

[kd3pc]

if you have the timbers, that will determine the height, building in a swale will help with the winds. Just look around at the barns in your part of the country - still standing and how they are sited with regards to weather and prevailing winds.

But that takes labor and money.

Steel is the least expensive, given the span and height you are looking for. Then wood would be for decor...unless it is all timberframe, which in your OP you mentioned NOT wanting all the posts and such.

Bests and I look forward to seeing your project move forward.

 

[buddyboy]

next time you are driving down the road take a gander at them wood telephone poles they use to hold up all them power wires.

take note of how tall them babies are.

now imagine putting two rows 30 feet apart and the poles eight feet apart in those rows.

now using your mind put some trusses up on top of them there poles.

take out your imaginary tape measure and see how tall the peak is.

now instead of using telephone poles use those fancy store bought squared ones.

i just drove buy a township pole building that is used to store salt for the roads... that thing was at least 35 to 45 to the peak, the door opening was 16 wide and at least 20 feet tall, I'm thinking it is that tall in order to let trucks back in and dump salt and leave dump bed in the up position while they drive out, also for front end loaders to raise all the way up to fill the trucks.

 

[WittHay]

There are a few hay sheds in our area that are made from telephone poles

I think they are 22' to 24' feet from truss to ground

There some older buildings that were built in the war times, 1940's to store commodity's
They are about 40 feet high but it would cost a small fortune to duplicate those buildings

 

[bjcouche]

3 stories like you are looking at is not a problem with a metal or wood post frame building. A 60' truss span should also be doable. However, when you start getting that large of a span, the steel trusses start to be more economical. I had a 40X64 building built with wood posts with steel trusses set on top. The trusses span 64' and the trusses and posts are spaced 16' apart. The perlins are on 2' centers. I had it built 5 years ago when steel was way more expensive, and the cost of steel versus wood for my span was about the same. I would expect that the steel truss would be your less expensive option now. You really need to get a few estimates to know what you are looking at cost wise though.
Brian

 

[NC357]

If you’re going steel trusses, I’m not sure why you’d want wood columns.

It's not uncommon to mix materials. I want to use trusses similar to this:
http://www.ebay.com/itm/111611939885
although I would probably want a steeper pitch than that.

Surely, I could install that on top of a 25' telephone pole no problem. That's where that "practical" word comes in. If I can find a wood pole that long (add 6 feet underground) it's probably too expensive, especially in the south. Big poles come from the firs in the north.

With that in mind, I'm not sure what the cost of a laminated post would be, but it makes the length part almost irrelevant.

I had an all steel shop before, I just didn't really like it. Couldn't nail/screw anything into the steel. Made more noise inside. I can always finish the inside of an all steel building with wood, but that won't be cheap either...

 

[bjcouche]

I would think a pole building would be just as noisy as a steel building, after all they use the same exterior corrugated metal. The Pole buildings are similarly challenging to finish off on the inside because the girts are often not spaced properly to installing 4x8 sheets of plywood, drywall, etc. Thus there's a lot of blocking or additional stud walls to put up to give structure to attach your wall finishing to.
As to long poles, laminated columns get more economical with longer lengths as compared to solid posts..... However, I've heard that my uncle in WI is getting used utility poles for fairly cheap and using them to construct a small cabin. I've heard another guy in OH is getting them cheap and sawing them into lumber. This leads me to believe that used utility poles might be an inexpensive option. It's worth looking into if you decide to go the pole building route.
Brian

 

[NC357]

Under 35 feet is an adopted code in many areas.
I know someone who set his below grade, in to a slope, to beat code.
Code at the time had no below grade statements but did have the height limit.
Mucho and huge French drains.

I may have to go this route, we do have a 35' height limit for all residential land, but I am working on having it rezoned for commercial where there is no height limit. 25' eave height plus a tall pitch roof will be close to the limit.

My land is almost totally flat, although the water table is kind of high due to the creek that runs through the middle. Digging down may be more trouble than it's worth, not sure yet.

I've thought about used utility poles, but won't they make the inside of the building smell? Especially on a hot summer day?

 

[kbs2244]

This is how they built the old one you had.
wood, long nails, heavy hammer, sore arm at night.

http://bioengr.ag.utk.edu/extension/extpubs/Plans/6411.pdf

 

[NC357]

This is how they built the old one you had.
wood, long nails, heavy hammer, sore arm at night.

http://bioengr.ag.utk.edu/extension/extpubs/Plans/6411.pdf

Oh yeah, I feel sorry for the guys who built that old thing, I ***** about a sheet of OSB and an 18v impact to screw it down. I can't imagine doing it board by board nail by nail, with some BIG freakin' nails! I get upset when I have to reload the nail gun. LOL

Even though my old barn was nearly 50 feet tall at the peak of the roof, no single piece of lumber that I could find was longer than 10 feet. I think this was due to the weight of the lumber, so the guys could get it in place without any machinery! Very cool old building, I wonder what it would cost in lumber and labor to totally recreate today...