Braces for a pole barn

[DennisArrow]

I have a 28 X 40 structure going up......12' wall height.....6x6 posts on 8' centers.........clear span trusses 4/12 on 48" centers........1x4x10' (rough lumber full dimension yellow pine) for purlins/lathe............
that is as far as I am along........half way done with putting up the lathe on 24" centers.........am overlaping the trusses by a foot on each end and staggering them by just laying the one that would butt up to the end of the next directly on top of the next one..........hope that makes sense.........got this recommendation from a Candadian government plan sight that says that doing it this way doesnt put as many nails in a small spot on the truss and makes a stronger joint.....
Over the last few days while I have been installing the lathe/purlins I have had the trusses braced with temporary V shaped braces that I am removing as I install the lathe.......

The structure is getting stronger and more stable.......can actually stand up on top of the lathe/purlins and shuffle from truss to truss without getting seasick from the motion .........I know it will become even stronger as the tin goes up...........

Question..........I used doubled 2x12 for my banding/sill with the posts sandwiched between.......using 3 3" lag bolts on each joint where the 2x12 joins or attaches to the post........hurricane straps on each side to attach the truss to the 2x12s.............OK THE QUESTION...............what angle should the knee braces be?????????.............am not going to put on siding for perhaps a year or so...........right now am thinking of using 6x6 down the side in a V pattern on each post...........one end will fit up between the 2x12s and the other lag bolted to the post.............this will happen to both sides.........in addition I plan to come off the truss down to the post with a 2x6 bolted to the truss and the post.........across the end another V pattern ..............wondering what structural member to use here........across the end there is just a single 2x12.............What angles would you put these braces on???????????????????? Is 6x6 overkill????????........Is a 2x6 on a 30 to 45 degree angle bolted to the truss big enough???????? thanks for the help........Dennis

 

[beenthere]

Not following exactly what you are doing, but I do know that walking on purlins (even 2x4's, let alone 1x4's) can lead to a sudden and possibly debilitating fall 12' to the ground. The purlins do not have the strength if there is a knot or an adjacent knot which results in steep wood grain at or near the mid-span of 4' between trusses. Be real careful up there, as if one breaks, you will come down quickly. I was a witness in an injury trial where someone was being sued because a worker walked on the 2x4 purlins, and fell about 12' to concrete. Not pretty.

Angle braces should be used at the ends, IMO, to stop the trusses from racking (swaying).

Good luck. Pictures would help understand better, and/or the site where you obtained your plans if they are shown on that site.

Wish you well up there. /forums/images/graemlins/wink.gif

 

[SPIKER]

I agree hard folling you so far.

6x6 for a cross brace is not needed as you get the strenght from the PULLING appart and each angles need to compliment each other. generally I think you are talking about bracing the side & end walls correct or are you talking about bracing the trusses?

I would get a roof on ASAP and if you have to leave side walls & end walls un-done for alittle while with proper bracing. as long as the roof is put on correctly.

rat boards should not but up end to end same with the purlins they should overlap. one 12' long 1x4/ 2x4 nailed down then 8' out (not yet to the end of the 12'one start the 2nd diminesional purlin borad right beside the first there can be a space then from the 3rd to the first but in-line with each other. with the 2nd board taking up the space between the 1st &3rd each one overlapping the others some. running these 24" appart is pretty close and is a good thing if you have to boards. closer means more nailing for the tin when the roof goes on. besure to use good nails or screws with sealing washers designed for metal roofing. /forums/images/graemlins/smile.gif

so back to bracing of the side & end walls . 2x6's braced so they form V's spaning longer distance at lower angles with long boards is better than short spans and more braces with short boards.. hope that made sence. 2 20' 2x6's forming one V from top middle down to bottom corner of a 36' building is better than making 2 V's using 4 shorter boards.

these can be nailed on the INSIDE of the building so that later the side wall 2x4's/6's can be nailed parrell with the ground for sheeting on the outside with out intafearing with the bracing. the braces can be then left or removed after siding & stringers are on.

markm

 

[DennisArrow]

Thanks for the help guys........Especially about walking safely on the roof...........not bragging about how spooky it is up there nor flippant about the hazards.........THANKS.......

Yes, am asking about bracing the end and side walls........does the angle matter?.........

Side walls: Here in Georgia I notice most of the sides are at a 45 degree or so angle with a 3-4 foot brace............why I was going to use 6x6 here is because it would sandwich in between the 2x12 sill/band, be easy to bolt up there with several bolts, and at the base attachment to the post have a large surface area to bolt onto the post itself as it butts up to the post.............

How about we solve this problem before working on the end walls/trusses .........I really do thank you for your help and thoughts.............cant find much advice about this particular problem, nor suprisingly much on the internet..........THANKS.......Dennis

 

[DennisArrow]

forgot to put in a couple of sites I used for reference.........

Link 1
..........and......................
Link 2

this latter one, M-9307L is the one I am refering to about bracing to the truss and post............lower right corner picture.......can one go in to the bottom chord of the truss and bolt it there or go all the way up on the diagonal member and bolt there?????.........thanks again

 

[chatcher]

On my 30 x 40 garage, I used short 2x6 braces sandwiched in between the 2x12 headers, at 45 degree angles, mitered on the post ends, and nailed to the posts. I used a brace everywhere I could (a few had to be omitted due to window and door locations - my ceiling height is 10'). I'm not sure if using 6x6 bracing would be much stronger. It would definitely be a lot more work.

For end wall bracing I mainly relied on the end trusses, which in addition to sitting atop the 2x12 header ends are nailed to the end posts which are cut off even with the top edge of the trusses. If you are worried about swaying before the siding is installed, you could leave some diagonal temporary bracing in place for now. Each component adds increases rigidity, including the siding and roofing. Mine has metal siding but the roof is asphalt shingles on OSB sheathing (trusses 2' OC).

 

[Chuck52]

I just used 2x4 bracing in my 28x32 pole barn. Mine has one long side open, so I used short 2x6 bracing cut at 45 degrees at each pole, but even there the 2x6 was at least partly for looks and 2x4 would have been strong enough. After I got my bracing on, there was no sway to my structure. Be sure to make triangles with the bracing and not parallelograms!

I don't know if anyone mentioned it or not, but when the siding goes on there will be some serious wind pressure at the eves, so be sure to put in some bracing diagonals from the top of the end trusses to the bottom of the next truss. I put in 2x4 bracing like that to each truss, as I am sure most folks do, but the inspector made a point of wanting extra bracing at the eve ends.

Chuck

 

[DennisArrow]

one more quick question.............am finishing the purlins/lathe on one side today.............it will be a couple more days before I get the other side ready for tin...........I did put some temporary cross bracing on the posts/truss this morning and it does help the racking........anyway....
QUESTION............it is storm season here in Georgia and I really do worry about wind loads on the roof once I get the metal down because it will be awhile till I put on the siding...........anyway.........imagine that it isnt even gonna have siding..............which is more important getting the tin on the roof or bracing the walls...........seems to me that if I get the metal on and a storm comes up it could very easily rack the walls and cause real problems...........or do I cover the trusses and structure to prevent warpage problems...........OR is it a chicken and egg thing........thanks.......dennis

 

[Chuck52]

Why put up "temporary" bracing? Just go ahead and put in the bracing on the walls and between the trusses. At that point, if you install the roof metal, there will be minimal wind force on the open wall structure and you will have something like a carport. A high wind could indeed take off the roof, but that could happen with the walls completed anyway. Are you planning to use nails or screws on the roof? I used screws and it was both efficient and probably stronger than nails. Without the wall covering, I'd make sure I had my trusses well tied down. As I mentioned before, though, my pole barn is open on one 32 foot side, and it takes the pretty high winds here in mid-Missouri without any problems so far.

Chuck

 

[DennisArrow]

Chuck.......thanks........am going to use screws with the sealing washer thing on the roofing.........

Temporary braces today cause I have not made up my mind what to do as far as materials for the bracing.........I have used hurricane brackets to fasten each truss to the 2x12s. One on each side of the 2x12 sandwich on each side of the post......the 2x12's are held to each post with nails and 3 3" self-taping lag bolts........

Hoping for a bit more input from here.........am deciding a think, for 6x6 braces on the walls.........one end will sandwich perfectly between the 2x12 sills, bolt them with through bolts, and the other end on a 45 degree angle bolted into the post with lag bolts..........QUESTION.......would you make these how long?????????????? am thinking 4-5 feet.........yes, I know they are heavy and hard to handle.....but boy what a brace.......I tend to overbuild and it will look great till I get the siding up......price at the local saw mill for a 6x6x10' pressure treated is $26...........so not toooooo bad if it does the job..........thanks......Dennis