I assume that the truss designer is aware the your spacing plan?
The truss between the 12'6" bay and the 8'6" bay will be carrying more weight then any other one.
Pole barn roof question
- Thread starter mfairbank
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I assume that the truss designer is aware the your spacing plan?
The truss between the 12'6" bay and the 8'6" bay will be carrying more weight then any other one.
Yea so im guess im just gonna go with 2x6's for them larger bays and 2x4 in the smaller bays just to be safe. Yea the guy that designed my barn is aware of the spacing. I am using double trusses for this project. so should be pretty strong
do they make 4x4 hangars or did you just toenail them into the truss?? and how did you space them?? 2' oc or a larger space. Did you actually save money by buying 4x4's rather than using just a 2x6.
Rowdy Raven
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I am not sure if they make 4x4 hangars or not. I think that I have seen such at Lowes. I used a steel truss that was welded out of 1.5x1.5" angle iron. The trusses are 10" high and 20' long. I predrilled them on 30" spacing and used 3"x3/8" lagbolts to secure the 4x4s to the trusses. Where there were lap joints I ran a carriage bolt from the top through the two 4x4 tounges and then through the steel truss and then put on the washer and nut. This may not be conventional but it sure did work well. I can walk around on the roof and it does not flex. I will try to post some pix when I go back up this week.
sweet sounds like a pretty solid idea!! yea i would love to see some pics
rambler
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Wow - not an engineered building, huh? Don't have a good feeling about the mis-matched spacings, that doesn't come out so good long term.
You don't live in snow country, I hope.
Up here in MN they use southern pine 2x4 Good grade, not construction or SPF junk) on edge over the top to span up to 9 feet. Don't know what to tell you on an irregular building like that, 12 foot span is unheard of on a wood building, they would do a 8 or 9 foot spacing and keep the roof trusses at regular spacings, put in cripple posts and big headers to span the doors.
Got a Bostich paper tape frame nailer tht does the short fat connector nails, works well. Sure would hate to try to pound those little fellas by hand, if you go with metal straps.
Saw more of the thread now, didn't all show up when I started replying. Guess you got it approved that way, with odd spacings. Huh. That's something different, don't see that around here. Snow would mess that sort of structure up in a few years, un-equal loading....
--->Paul
It's very common around here. Huge freestall and livestock buildings mostly. They typically use the LamPly brand trusses then.
Why? If the rafters/trusses are designed for the extra load there is no issue.
You could space the trusses 24' o.c. and use 2x12s for purlins if you want.
beppington
Elite Member
Can ya'll help me with terminology? I keep reading "purlin" on the various barn threads, but don't know which piece that is ... ?
A purlin sits on top of the rafter/truss and runs perpendicular (parallel to the ridge). If you have rafters 2' on center and sheathing, you don't use them, but if you have a metal roof, you don't need the sheathing so you need something else to fasten to. If the rafters/trusses are too far apart to use 1x or 2x on the flat, you can stand them on edge to make them stiffer. There are several ways to use them. Most common is simply on top of the rafters, notched and inset was used a lot in the old post-and-beam, or hung off the sides of the rafters with hangers which is what these guys are talking about. While you can't use longer stock and span several trusses that way, it does mean the roof is closer to the trusses so it makes a little better use of the internal space, especially if you have a loft or attic.
Or if you prefer, sort of like a girt except on the roof instead of the wall.
jml755
Silver Member
First off, I'm no engineer, but every pole barn I've been involved in building or seen around here is Michigan has 2x4 purlins laid flat with usually 4' OC spacing on the trusses. I've seen some with 2' OC truss spacing as well. 8 ft? I don't know about that. Would seem to create an awful springy roof and tough to compensate for to save a few bucks in trusses on such a small building. I know I wouldn't build a P.B with 8' spacing.
The issue of trusses being over a wider span (like a door opening) is addressed with a proper sized header above and across the opening and stub post(s) between that header and the header that the trusses rest on. Usual 10' door openings here have 2 - 2x10s as a header. 12' opening? 2x10s might do it or go to 2x12's. Or you could look into glue-lams which I have no experience with but are are being used more and more as structural replacements for solid lumber. It shouldn't be hard to figure out what you need to span 12' and carry the roof load. In any case, it seems that your slightly larger than normal door openings are driving you to costly and complicated roofing decisions when I don't believe they need to.
The issue of trusses being over a wider span (like a door opening) is addressed with a proper sized header above and across the opening and stub post(s) between that header and the header that the trusses rest on. Usual 10' door openings here have 2 - 2x10s as a header. 12' opening? 2x10s might do it or go to 2x12's. Or you could look into glue-lams which I have no experience with but are are being used more and more as structural replacements for solid lumber. It shouldn't be hard to figure out what you need to span 12' and carry the roof load. In any case, it seems that your slightly larger than normal door openings are driving you to costly and complicated roofing decisions when I don't believe they need to.