Pole Barn Question
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Topic: Pole Barn Question
Posted By: Steve-Ohio
Subject: Pole Barn Question
Date Posted: 08 Feb 2010 at 11:19am
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I am having a 30' x 40' x 10' pole building built this spring by a contractor-----will have county building permit. The sides will be metal as will as the roof.
The roof will be 5 pitch with trusses 4' on centers and 2' x 4' perlins with 7/16' OSB and metal roof on top of OSB. Question for you folks--what do think about trusses being 4' on center with it carrying the weight of OSB and metal sheeting ? It will be approved by county engineers.
Tks
Steve
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Replies:
Posted By: Dick L
Date Posted: 08 Feb 2010 at 11:31am
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Here I put the 2" x 4" on edge when the trusses are on 4' centers and lay the 2" x 4" flat on 2' centers.
The truss builder needs to know what and how to build in snow load. The contractor probly has it covered or at least should.
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Posted By: Gerald J.
Date Posted: 08 Feb 2010 at 11:49am
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OSB is HEAVY! My three machine sheds without OSB have trusses at 9 or 10 foot intervals. Those trusses are made of large 2x, no 2x4 tops or bottoms. More like 2x8 or 2x10 and are made of the best quality lumber. Really beautiful lumber. The 2x4 purlins are on edge in all of them. Why the OSB? Gerald J. |
Posted By: BrettPhillips
Date Posted: 08 Feb 2010 at 11:55am
| I had a 32 x 48 x 12' building put up this past summer with three 16 ft bays, and a 2 ft overhang all around to help keep things dry. Trusses are similar pitch to yours and are engineered for 4 ft. spacing with 2 x 4 purlins and metal roofing on the purlins (no OSB). It has held up well to some strong winds and now a bit more than 2 ft of snow. As you will hear from lots of folks, the only thing I would do differently would be to make it 64 or 80 ft. long... |
Posted By: Eric[IL]
Date Posted: 08 Feb 2010 at 2:20pm
| Steve, You might want to ask your contractor how many inches, center to center, that he is figuring for the 2x4 purlins. With the additional weight of the OSB plus sheet metal over the 4' span, you may want to decrease the distance from say 24" down to 18"? Or, you could put 2x6 purlins every 24"? You may also want 1x4 flat fur strips on top of the OSB to nail or screw the sheet metal. These 1x4 spaced at 2'or 3' would allow the sheet metal to flex some & offer an additional air gap for insulation purposes plus it wouldn't add much expense. |
Posted By: tadams(OH)
Date Posted: 08 Feb 2010 at 2:42pm
| Steve when I built my pole building, we use 4' spacing for the trust with 2 X 4 s on edge, then paper for a moister barrier, then the metal screwed down. It is a 4/12 pitch and has held the snow load well. Tom |
Posted By: TexasAllis
Date Posted: 08 Feb 2010 at 3:55pm
Just tell your truss manufacturer what you plan to top them with and they will do the rest but sounds like you should be ok.
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Steve-Ohio wrote:Posted By: firebrick43
Date Posted: 08 Feb 2010 at 8:36pm
| If your using metal roofing, why OSB? I see no advantages |
Posted By: jmm
Date Posted: 08 Feb 2010 at 8:51pm
| I worked for a truss company for 2 years. just make sure they know the loading and spacing |
Posted By: Steve-Ohio
Date Posted: 08 Feb 2010 at 9:24pm
| OSB for a vapor barrior. |
Posted By: Eldon (WA)
Date Posted: 08 Feb 2010 at 9:32pm
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You can save $$$$ by using the 2" insulation blanket instead of OSB. My 40 x 84 barn is built on 12' centers with 2x8 gerts set between double trusses with joist hangers. Snow load is 40#...standard design for our county. ------------- ALLIS EXPRESS! This year: |
Posted By: Dale Hardtke
Date Posted: 08 Feb 2010 at 9:43pm
| NO actually the OSB is less per square foot than the insulation |
Posted By: Eldon (WA)
Date Posted: 08 Feb 2010 at 9:47pm
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But the underlying framing and trusses are more expensive. ------------- ALLIS EXPRESS! This year: |
Posted By: michaelwis
Date Posted: 08 Feb 2010 at 10:57pm
------------- WD WD45 DIESEL D 14 D-15 SERIES 2 190XT TERRA TIGER ac allcrop 60 GLEANER F 6060 7040.and attachments for all Proud to be an active farmer |
Posted By: jaybmiller
Date Posted: 09 Feb 2010 at 6:27am
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My 40 x 70 x 14' shop has trusses every 12'(4/12 pitch),built in 1963,'old school',still straight,level and plumb! Roof has 3 x 4 purlins every 2',sports a metal roof.That leaked so the previous owner layed down 1/2" plywood and 2 layers of shingles.
Last summer all the shingles came off and a new single layer went down.
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Posted By: roughstock
Date Posted: 09 Feb 2010 at 7:22am
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Seems to me if you are having it built by a contractor, it should be code. If not, make him rip it up and replace it at his expense. I highly doubt he will build something that will fail. That's my two pennies. Brian |
Posted By: JimVH
Date Posted: 09 Feb 2010 at 7:49am
| It seems to me that you should be asking the questions of you contractor. He is the one who should be aware of your local requirements as to loading and building codes, and also is the one to stand behind it. If you do not have confidence in your contractor, then perhaps he is not the best choice to build it. There are numerous methods of building a post frame building, and some are better for specific uses than others. Compare methods with your contractor, and let him give you the best advice for your situation. |
Posted By: CTuckerNWIL
Date Posted: 09 Feb 2010 at 8:45am
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I don't understand the vapor barrier idea. OSB will come apart after being exposed to "vapor" and water condenses on the inside of the steel, given high humidity and the temperature below the dew point. OSB will not stop condensation on the inside of the steel. Our new Barn for the tractor club has 4 inch panels of foam insulation and OSB on both sides. Then there is a layer of 1x4's to stand off the steel roofing.
------------- http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF |
Posted By: ac45
Date Posted: 09 Feb 2010 at 8:46am
| OSB is heavy, id go the styrofoam sheets for a vapor barrier, may cost a little more, but will work better, and a lot lighter. you need to keep the roof itself as light as possible, there shouldnt be an issue with the purlins faiing, It is usually always the trusses that fail from snow load or weight. |
Posted By: Dakota Dave
Date Posted: 09 Feb 2010 at 9:19am
| OSB will not work as a vapor barrier. any time you put steel over wood you need a vapor barrier to prevent the wood from rotting. |
Posted By: Dale Hardtke
Date Posted: 09 Feb 2010 at 10:13am
| Eldon: Making a statements like "You can save $$$$$ by using a 2" insulation blanket" and "underlaying framing and trusses are more expensive" indicates you are knowledgeable enough to make an argument, but have not checked the facts. OSB is less per sq. foot than 2" insulation. The extra load carring capacity of the truss/purlin structure needed to carry the OSB would be so small ,that it would not even be a factor. 7/16 OSB = 1 lb./sq ft. This is 1/40 of the engineered load carring capacity of the roof structure. To use "underlaying framing and trusses are more expensive" as a consideration not to use some kind of sheathing OSB, plywood or wafer board would be a statement to be made for the sake of argument, but not based on engineering facts. |
Posted By: Gerald J.
Date Posted: 09 Feb 2010 at 10:23am
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At a recent home show, I saw a metal roofing made to prevent condensation without any other liner. It was flocked with a fabric like fuzz. The pole building salesman said that was to prevent condensation. Not much insulation but some. He did not try to sell me a building because he had failed at that a few years ago. Gerald J. |
Posted By: Bob-Maine
Date Posted: 09 Feb 2010 at 3:42pm
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I built my pole barn myself. used 2x8 rafters with 2x4 purlins 24"O.C., then steel. When weather and temp are right, it's like raining inside. But that's not a problem.
When I built my 28 x 40 shop, I put 1/2" CDX plywood over the rafters, building paper (tar paper), 2x4 purlins and steel roofing. I didn't want it to "rain" on the loft. And it doesn't. Steel roofs result in condensation so the vapor barrier is important if you don't want moisture. Leave the OSB off if you don't use a vapor barrier but plan on some dripping. Bob@allisdowneast |
Posted By: Dave(inMA)
Date Posted: 09 Feb 2010 at 5:25pm
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Roof on my barn is 5/8" cdx, Tri-flex and metal. There are condensation channels in the metal to drain water away. The Tri-flex is essentially a water-proof membrane. According to the local metal roof guys, that roof is good for 40+ years.....well past the point where I will be using the barn. Why the plywood? We have wondrous new snow and wind load requirements here in Massachusetts. ------------- WC, CA, D14, WD45 |
Posted By: firebrick43
Date Posted: 09 Feb 2010 at 9:12pm
| If you use osb you need a water barrier between the metal roof and osb. It will be damaged otherwise. I would consider some 1/2" fanfold Styrofoam. Installation cost will be lower for it in saved labor and material cost should be lower when you take the OSB + vapor barrier cost into account. |
Posted By: DanWi
Date Posted: 09 Feb 2010 at 9:29pm
| One thing no one has mentioned is if you use the shed to work in it won't sound so bad during a rain storm if you have some kind of insulation in the roof. |
Posted By: Dave(inMA)
Date Posted: 10 Feb 2010 at 6:29am
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My barn is surrounded by oak trees.....gets pretty noisy in there when the acorns start falling! ------------- WC, CA, D14, WD45 |
Posted By: Bob-Maine
Date Posted: 10 Feb 2010 at 8:47am
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Dave, Not to mention the gray squirrels chasing those acorns across the roof. Those little claws could be like chalk on a blackboard.
Bob@allisdowneast |
Posted By: Dave(inMA)
Date Posted: 10 Feb 2010 at 1:56pm
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Bob, ya could be right, though I didn't see any of the wee buggers last fall when the nuts came down! I do know that the roof got mighty slippery - I think due to pollen and dust - not sure even the squirrels could stay on it. ------------- WC, CA, D14, WD45 |
Posted By: joe(wi)
Date Posted: 10 Feb 2010 at 2:49pm
| I built a pole barn 5 years ago in northern wi. Spend the extra 200.00 and go with trusses 24" on center. I used attic trusses for the extra storage. I applied 7/16 osb, roofing paper and then put my metal over the top. You do not have to worry about any snow load, first warm day it will slide off. This is the second one that was done this way and we would not do it any other way. All the holes for the roof were pre-drilled on the ground on the overlap. This allowed me to hang the 22' pieces by myself. -Joe |