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jjlrrw
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# Posted: 18 Aug 2016 04:20pm
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I have a 24x40 pole barn, thinking about using 7/16 OSB on the walls and ceiling then blowing insulation.
One area I don't fully understand is the ceiling. the trusses are the "Fink" style a "W" between the the lower 2x4 and the upper 2x4's. The trusses 4/12, run the 24' span and are on 4' center.
I don't feel there is enough area to attach the OSB to the trusses with a 4' center without adding more nailers. I was thinking of...
1) running 2x4's under the trusses the length of the barn 40' every two foot then attach the OSB to the 2x4's, using the 2x4's like furring strips.
2) placing 2x4's between the trusses perpendicular to the trusses every 2' so the 3.5" width of the 2x4 is vertical like the trusses.
Other options?
The other concern is the extra added weight, using 2x4's, OSB and insulation it's adding ~3.5 # per sq foot.
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sparky30_06
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# Posted: 18 Aug 2016 06:09pm
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When I finished off my pole barn the trusses are spaced 8' on center. I ran 2x4's every 2 feet between the trusses and spaced them 1 1/2" up. then came back and laid a 2x4 on the bottom half way between, so I would have a nailer every 4'. I then used the same tin that was on the roof to make the ceiling. then blew fiberglass on top of that with no problems. The builder usually just spans the sheets of tin but they will bow a little with the weight of the insulation. I don't see why you couldn't just add more nailers and do the same thing. I would recommend screwing the nailers instead of nailing them. maybe even some liquid nail for extra strength.
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bldginsp
Member
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# Posted: 18 Aug 2016 08:10pm
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I'd find out if the trusses were engineered to accept the ceiling weight.
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creeky
Member
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# Posted: 18 Aug 2016 08:49pm
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Pole barns are made for super insulation.
I used 6" roxul in the "attic" and closed off with 1.5" of polyiso. Gave me something around r32.
Polyisoboard was also used on the walls. I outside dressed in 1" polyiso (three season). Then two years later added 1.5" between the girts (2x4). and 1" inside. 3.5" polyiso gives me r23. give or take. 4 season.
The nice thing about putting polyiso between your girts is that it stiffens the building. and using 4x8' polyiso sheets nailed to the rafters both holds the roxul up and eliminates the need for osb or whatever.
I bought my polyiso sheets "used." cost me 8 bucks a sheet. so for less than the cost of osb/whatever I got r10. might want to look into that.
apb pole barns has some pretty good info.
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jjlrrw
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# Posted: 18 Aug 2016 09:36pm - Edited by: jjlrrw
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There is a picture of the truss a page or two down. So far my google skills have come up empty trying to find out the amount of weight it can support for ceilings. Somewhere is stated 20# per sq foot but not sure what they were referring to.
http://cortezcolorado.net/wp-content/uploads/2014/05/fink-truss.png
thanks
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bldginsp
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# Posted: 18 Aug 2016 11:14pm
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The only way to find out what a truss can carry is to have or get the engineering on it. It's entirely possible that your trusses are only strong enough to support themselves and the roofing, no more. Barns are often designed and built to bare minimum standards, or less. Many rural areas have no building requirements for agricultural buildings at all. I would make an accurate drawing of the trusses, and a plan of the barn, and have someone with structural knowledge assess it for you, if you plan to add ceiling supported only by the trusses. However, if you add interior walls that can support ceiling joists, the ceiling could be supported independently of the trusses.
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JDPugh
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# Posted: 19 Aug 2016 02:47am
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You really do need to verify the truss data before adding all that additional weight. In some areas, farm structures are not required to meet the same code requirements as residential structures.
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sparky30_06
Member
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# Posted: 19 Aug 2016 07:21am
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the questions also comes down to why are you using OSB on the ceiling?? I would highly recommend white R panel. It's light weight, you won't have to worry about the additional load on the trusses, it's already painted and it goes up easy and fast. you can get it in 22' sheets, so you only end up with one seam in the middle.
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