Truss questions

[Rodmo1]

Hello all,

this is a continuation of my previous pole barn questions thread. Two days ago I started setting trusses. My pole barn package came with little info regarding the proper bracing of these trusses. They are 24' spans set 24" on center. I have them lined up and temporarily braced beautifully. This morning I ran 3 continuous lateral braces on the bottom chord (one exactly in middle and the other two are ran just outside of where the "w" pieces connect with the bottom chord. I believe this should be perfectly sufficient. My main question regards the perm. bracing of the upper parts of the trusses. After speaking to the supplier they recommended running two 2x4's straight through the trusses attached to the inner webbing towards the top. He seemed somewhat uncertain of the exact recommended way. This certainly sounds easy enough to do, however I would think you would need some sort of diagonal bracing to keep them from slouching over. I understand that the roof will take care of most if not all of these stresses when it is installed however it seems after reading online that I should still install these diagonal braces. Wondering what all of your thoughts are?
Question #2
Once all the trusses were set upright I noticed that they generally only touch one of the headers. Some of them have over 1/8" of daylight shining through.. Is this normal? I could easily shim the opening if this is something to be concerned over.

Much appreciative,
Rod M.

 

[Rodmo1]

I failed to add that they are 4/12 pitch

 

[tommu56]

Mine have the loggitudinal ones like yours too.
It also has an angle brace from the top (at the ridge) on the center verticle truss member on the end truss back to the 3rd truss at the bottom of the verticle truss member and nailed in to the center of the verticle trus member on the second truss.
This forms a right triangle to keep the truss top from falling out

tom

 

[Duffster]

IIRC correctly you are having a plywood and shingle roof

The plywood will hold the top of the truss, so no need to woory about it falling out

The angle brace holds the wall line stiff were the gable truss meets the wall

You can brace this two ways, if you have a center upright in the truss you can put it along side that or put one on each of the long webs in the "W"

Most will put it with the bottom on the lateral brace and the top on the gable at the ridge but for a sheathed roof the opposite is better IMO

Probably not an issue with your size building but any truss web member over 8' should have a lateral brace or a T brace

ps Your trusses should have come with detailed drawings and bracing details

 

[tommu56]

Rod
Here is a dyi link and shows some bracing details.

http://www.public.iastate.edu/~mwps_dis/mwps_web/plans/truss_24.pdf

on page 4 called wind bracing mine is from the 1 to the 3 truss in an x shape on both ends
tom

 

[Rodmo1]

Okay if I read this correctly the angle bracing on the ends is only to stiffen up the gable truss. My building has a cross piece that spans the gable truss at the top of the gable end posts. The gable truss is nailed many times into this cross piece tightly anchoring it into the posts. It sounds like the guy at the lumber yard was correct and all I should do is run two lateral braces on the w's in addition to what I already did. (my trusses dont have a vertical center piece).
Another question...anchoring these braces with 16p nails...are these too big (2x4 chords) and actually weakening the members?

 

[Duffster]

Okay if I read this correctly the angle bracing on the ends is only to stiffen up the gable truss. My building has a cross piece that spans the gable truss at the top of the gable end posts. The gable truss is nailed many times into this cross piece tightly anchoring it into the posts. It sounds like the guy at the lumber yard was correct and all I should do is run two lateral braces on the w's in addition to what I already did. (my trusses dont have a vertical center piece).
Another question...anchoring these braces with 16p nails...are these too big (2x4 chords) and actually weakening the members?

You need the angle brace unless the gable end posts reach to the top chord of the truss, even then it would still be reccomended

The 16d's are fine

 

[Gazelle]

You should have a HIB detail sheet showing the recommended bracing. This would be at each end of the building and at every 30' in between, roughly ea. at a 45 degree angles. The bracing should be in the top and bottom chord planes as well as any web members. Additionally, the gable studs should be braced as well. Lastly, each truss has its own bracing requirements whether its for the chord members or for the web bracing, the sealed drawings for each truss design should specify clearly what these are, if any.

 

[MikeD74T]

Rodmo1, Don't rely on your own or the salesman's best guess unless you're willing to take full responsibility for any structural failure. Get a spec sheet from the truss manufacturer specifying the bracing requirements. Trusses are not stand alone elements but are one part of a completed structural system.
Look here Literature at the encylopedia of trusses section, especially the bracing section. Also note that it's very plainly & strongly stated that proper bracing is the responsibility of the builder.
I've erected many acres of trusses, wood-steel- roof- & floor. Bracing is everything & bracing that forms a triangle is essential. MikeD74T

 

[Egon]

Trusses are not stand alone elements but are one part of a completed structural system.

Take note of the above advice and make sure you have the correct vertical and horizontal bracing in place.

Have any of you ever seen the typically large building under construction that has just had the trusses installed. Overnight a wind comes up and the next day the trusses are all laying down in pieces?