Any architects/builders care to weigh in on a pole barn plan?

...dave · Feb 15, 2007

My plan is to build a slightly oversized 2-vehicle carport, with the intention of enclosing it later on as funds allow. Here is what i'm looking at (i apologize for my lousy grasp of the terms involved):

All pressure-treated lumber for frame
20' x 24', 9' inside headroom, 1:3 gabled roof above
"Poles" will be nine 4 x 6 x 12' timbers set in 18" deep concrete
Rectangular frame built around poles with 2 x 8 lumber (10' and 12' lengths) bolted to poles with 2" extending over the tops of the poles
Single run of 2 x 8 x 10' boards lengthwise across center, inset 6" into notches cut into poles.
2 x 6 stringers run between front/back panels and center support to create flat floor for later attic storage, on 2' centers
2 x 6 x 4' uprights to support gable header
2 x 6 single gable header (parallel to center support below)
2 x 4 rafters on 2' centers (should work out to roughly 12' 8")
19/32 OSB roofing, covered by tar paper and shingled to match house

Does this seem solid? Does it make any sense without pictures? If it seems overbuilt, i'm in a hurricane-prone area. If it seems underbuilt, well, i guess i'd better rethink :lol_hitti

Cheers,

...dave

Bevis · Feb 15, 2007

Of course you'll have all the hurricane straps too. Might think about putting some j-bolts in your floor when you pour the slab for the bottom of the walls. Sounds like it should be stout enough.

I'm getting ready to build myself a 48x30x12 Pole barn, i'm sure it's overkill, but my buddys held up when Wilma blew through in '05.

Itzkwik · Feb 15, 2007

If you're in a hurricane area, you might want to go with a longer post and put a little more of it in the ground. If it was me, I would put 2' or 3' in the ground.

Sundowner · Feb 16, 2007

rent a post hole digger and go at least 36" down. 48" is better. personally, I like to buy sheets of wire mesh reinforcment, roll it into a cylinder, and stick it into the hole before pouring the concrete, just as an added measure.

get some good long J-hook anchor bolts and stick them in the wet concrete so you can bolt down good galvanized post bases. don't use drilled anchors like red-heads, they don't have the same grip. buy post bases that have provisions for positively bolting down to the concrete and allow for real attachement to the post. I'm talking a through-bolt, not 3 or 4 drywall screws or Teco nails.

building a carport is different that building an enclosed garage. in real design storm wind, like 80 mph, you're talking about 40psf of pressure trying to use your carport like a kite. you need to take holding it down much more seriously than holding it up.

I'd like to think I've got a pretty good idea of what I'm talking about, since I'm one of dem structural enigimineers.

1320stang · Feb 16, 2007

Put gravel in the bottom of the hole before putting the pole in, then concrete. This way if any water gets between the pole and the concrete, it has someplace to go instead of rotting the post out from the bottom up.

neblinc · Feb 16, 2007

When my building was built by Astro Buildings, they used 2 x 6's laminated together and used limestone rock to fill the hole with a "pad" at the bottom. (see link)
The holes were deep and wide and any water will just flow through.

Randy

1320stang · Feb 16, 2007

That's how Morton does it as well. Up to about 48" above ground, the 2x's are treated, then they're untreated.

...dave · Feb 16, 2007

Sundowner said:
rent a post hole digger and go at least 36" down. 48" is better. personally, I like to buy sheets of wire mesh reinforcment, roll it into a cylinder, and stick it into the hole before pouring the concrete, just as an added measure.

get some good long J-hook anchor bolts and stick them in the wet concrete so you can bolt down good galvanized post bases. don't use drilled anchors like red-heads, they don't have the same grip. buy post bases that have provisions for positively bolting down to the concrete and allow for real attachement to the post. I'm talking a through-bolt, not 3 or 4 drywall screws or Teco nails.

Just to clarify, i was planning on digging out the hole, inserting the pole, and filling the concrete in around the pole, not using the concrete as a base for the posts...

i'm amazed by the 48" depth figure... i would have thought that would be way past the point of diminishing returns. What diameter hole would that be for 4x6 posts?

What about drilling perpendicular holes in the posts at 6" and 12" from the bottom and inserting rebar rods? Figure it couldn't hurt...

And thanks for the gravel tip... wouldn't have thought of that :bowdown:

Cheers,

...dave

Willy Victor · Feb 17, 2007

Around here (Lower MI) They don't use any concrete for posts when erecting a pole building, reason being eventually the posts will rot due to water running down the post.

Willy

Abodyracer · Feb 18, 2007

Willy Victor said:
Around here (Lower MI) They don't use any concrete for posts when erecting a pole building, reason being eventually the posts will rot due to water running down the post.

Willy

Thats the same way they do it here.

Wood posts set in concrete will rott prematurally. All that is needed is to drop a concrete pad in the bottom of the hole and backfill, compacting the backfill as you go. Any water that gets in will be absorbed by the dirt rather than the post.

1320stang · Feb 18, 2007

Willy Victor said:
Around here (Lower MI) They don't use any concrete for posts when erecting a pole building, reason being eventually the posts will rot due to water running down the post.

Willy

Which is why you put the gravel in the bottom of the hole. The water cant sit against the post. My father had a 60'x120'x16' Morton building build over 30 years ago that's still standing even with the straigh line winds we get in Oklahoma

Sundowner · Feb 19, 2007

...dave said:
Just to clarify, i was planning on digging out the hole, inserting the pole, and filling the concrete in around the pole, not using the concrete as a base for the posts...

i'm amazed by the 48" depth figure... i would have thought that would be way past the point of diminishing returns. What diameter hole would that be for 4x6 posts?

What about drilling perpendicular holes in the posts at 6" and 12" from the bottom and inserting rebar rods? Figure it couldn't hurt...

And thanks for the gravel tip... wouldn't have thought of that

Cheers,

...dave

I don't like to bury the posts in the concrete. it means that the post is no longer servicable or replaceable below the line of the concrete. it eliminates the possibility of rot and it eliminates the possibility of concrete cracking from the movement and swell of the wood post cast into the middle of it. If it were mine, I'd want an uninterrupted mass of reinforced concrete with steel anchors in it connecting solidly to the wood post. yeah, I know thepost buried in the hole with rocks is the age-old and time-tested method. but for every 200 year old barn yousee standing, there were 5 others around it that rotted and fell down

Alex · Feb 19, 2007

Anyone ever try something like this
http://www.postprotector.com/index.html

I thought about it but went with the concrete pad in the hole with crushed stone then compacted dirt :thumbup:

46x26x16h polebarn

The rebar thing will work for a smaller sheds 10x10 or 12x12
just my 2 cents

wrigh003 · Feb 19, 2007

...dave said:
My plan is to build a slightly oversized 2-vehicle carport, with the intention of enclosing it later on as funds allow. Here is what i'm looking at (i apologize for my lousy grasp of the terms involved):

All pressure-treated lumber for frame
20' x 24', 9' inside headroom, 1:3 gabled roof above
"Poles" will be nine 4 x 6 x 12' timbers set in 18" deep concrete
Rectangular frame built around poles with 2 x 8 lumber (10' and 12' lengths) bolted to poles with 2" extending over the tops of the poles
Single run of 2 x 8 x 10' boards lengthwise across center, inset 6" into notches cut into poles.
2 x 6 stringers run between front/back panels and center support to create flat floor for later attic storage, on 2' centers
2 x 6 x 4' uprights to support gable header
2 x 6 single gable header (parallel to center support below)
2 x 4 rafters on 2' centers (should work out to roughly 12' 8")
19/32 OSB roofing, covered by tar paper and shingled to match house

...dave

You just pretty closely described what I got when I bought this place. If I wasn't spending so much time and effort on the rehabbing the actual house attached to it, I might have closed it in already. Mine's stupid overbuilt, IMHO, but I know it's not going anywhere. Lemme go shoot a picture.

Forgive the bad quality and the finger in front of the lens on the overview shot- it's dark out and I'm still learning to shoot wife's DSLR.

It's a 9-post carport, and each post is a 6x6 sandwiched up with a pair of 4x6's. Like I said, seems like overkill. The second picture shows how they rested the header on top of the sistered up 4x6, which I guess would be one way to do it. The third picture shows how the corners are constructed. Overall, it's there. Nothing fancy at all, but it keeps us from having to unload the groceries in the rain for now, so maybe later on the garage.

Looking at it, I wonder if I'll be better off tearing it down and starting over, but I just wanted to show it, it might save you some grief and/or give you an idea.

...dave · Feb 20, 2007

wrigh003 said:
It's a 9-post carport, and each post is a 6x6 sandwiched up with a pair of 4x6's. Like I said, seems like overkill. The second picture shows how they rested the header on top of the sistered up 4x6, which I guess would be one way to do it.

Dang, lumber must have been a lot cheaper when they built that!

i got a line on railroad crossties over the weekend... 8x8x12 creosoted, for a dollar a foot :bounce:

And some 2 x 10 x 22-footers, so i think i can eliminate that center pole as well... now i just need to figure out exactly where i'm gonna plant this beast.

:beer:

...dave

wrigh003 · Feb 20, 2007

...dave said:
Dang, lumber must have been a lot cheaper when they built that!

I hope so. Pretty much everybody who comes by my house who hasn't been there before comments on it. The side door is the main door that people use, and it's funny. Lots of walking past, noticing this huge beam, double take, etc. "Who built THAT?" "Dunno, but they didn't want it walking off..."

:lol_hitti

Any architects/builders care to weigh in on a pole barn plan?

...dave

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Bevis

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Itzkwik

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Sundowner

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1320stang

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neblinc

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1320stang

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...dave

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Willy Victor

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Abodyracer

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Sundowner

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Alex

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wrigh003

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...dave

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wrigh003

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