MH8675309
Platinum Member
It does seem small - usually they're 2 x 8s. Then again i've seen worse,, you probably have too
Roof Beam replacement.
- Thread starter RobertEH
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That style is standard practice here. I'm a building contractor in North Idaho, where the OP is located. Depending on roof pitch, sometimes 2x8's are spec'd, but 2x6 are the standard. As we see in this case, if something fails, it's rarely the purlins, it usually a poorly designed truss or the truss to post connection. In fact, I don't think I've ever seen a 2x6 purlin spanning 10 feet fail in a building with a 4/12 or steeper pitch, and this is an area where 60-90 lb/sq. ft. snow loads are the norm. Typically, purlins here are spaced 2' OC, same as what you mentioned, which is how I guessed at 30' wide for the building. If the building is 24' wide, those purlins are spaced much closer together than normal.
Chewwy
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IMO the biggest weakness in the truss is the lack of gussett plates. The truss is secured at the joints by what appears to a few bolts.
At the outside joint the forces are being applied in line with the grain, causing the bottom chord to split and then crack.
At the outside joint the forces are being applied in line with the grain, causing the bottom chord to split and then crack.
Streetcar
Veteran Member
DO NOT REMOVE MEMBERS OF THE TRUSS WITHOUT ENGINEERING REVIEW. This could lead to collapse of truss.
2manyrocks
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While I can appreciate wanting to help a neighbor, there is also the question of whether this is getting so complicated or risky enough to suggest the owner bring in a contractor with insurance coverage?
The truss was built to begin with without engineering review.
OP
RobertEH
Silver Member
Couple updates:
The 2x6 failed (splitting along the grain where the nails attaching it to the wall post were). The truss cord has slipped below that under the edge of the truss
So the plan of attack now is to try to shore it up to the best of our abilities, and then have someone look at the entire roof and make some recommendations.
1. we will try to compress the 2x10 cord and compress the gap in the split as best we can
2. We will remove the failed 2x6 from the wall post and replace it with a 6x6 or similar that runs from the cord to the ground
3. we will then sister in a couple of 2x10s along side the split chord to stabilize it
4. We will replace the "tree" in the center of the truss with a 6x6 or similar.
That should help considerably and then we can look at other options with an engineer.
Appreciate the insights - we don't know the physics of this terribly well so I think it is best we move with this more conservative approach.
- The shop is approx. 50 feet long, and 30 feet wide
- There are 4 sets of struts about 12 feet apart
- The cords are made from a pair of 2x10's
- Both sides of that one truss cord are fractured
The 2x6 failed (splitting along the grain where the nails attaching it to the wall post were). The truss cord has slipped below that under the edge of the truss
So the plan of attack now is to try to shore it up to the best of our abilities, and then have someone look at the entire roof and make some recommendations.
1. we will try to compress the 2x10 cord and compress the gap in the split as best we can
2. We will remove the failed 2x6 from the wall post and replace it with a 6x6 or similar that runs from the cord to the ground
3. we will then sister in a couple of 2x10s along side the split chord to stabilize it
4. We will replace the "tree" in the center of the truss with a 6x6 or similar.
That should help considerably and then we can look at other options with an engineer.
Appreciate the insights - we don't know the physics of this terribly well so I think it is best we move with this more conservative approach.
2manyrocks
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If you could please post a picture showing what you just posted, that would be helpful to me understanding this better.
My concern would be how to be 100% certain of holding the structure together if doing this job means that one key structural element has to be removed and replaced?
It's also starting to sound like a hard hat kind of job.
My concern would be how to be 100% certain of holding the structure together if doing this job means that one key structural element has to be removed and replaced?
It's also starting to sound like a hard hat kind of job.
CliffordK
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I've come to like ratchet straps. Probably similar to the come-a-long.
You can purchase 4" ratchet straps at Harbor Freight, or any truck stop. You'll need a couple of them. I'd loop around the posts on each end. It doesn't have to be 100% at the top of the post, but down a couple of feet is probably fine to give you room to work.
Add a backup strap if you wish.
Your truss won't completely collapse as long as you have it supported from spreading, and have the center supported.
I'd also throw a ratchet strap on the diagonal truss member up to the top truss member to keep it from moving when you disconnect it.
You'll have a bit of a problem aligning bolt holes. You may be able to drill through from the back side, or make some centering pins to mark where to drill.
Some bolt holes could also be moved 6" one way or another at the point of overlap between the two boards.
Get a plan, and all your ducks in a row before starting, and you should be fine.
Actually, I really like ratchet straps. You could also hold your horizontals in place with ratchets. One strap for the back beam, and one for the front.
Leave the tree for posterity!!!
You can purchase 4" ratchet straps at Harbor Freight, or any truck stop. You'll need a couple of them. I'd loop around the posts on each end. It doesn't have to be 100% at the top of the post, but down a couple of feet is probably fine to give you room to work.
Add a backup strap if you wish.
Your truss won't completely collapse as long as you have it supported from spreading, and have the center supported.
I'd also throw a ratchet strap on the diagonal truss member up to the top truss member to keep it from moving when you disconnect it.
You'll have a bit of a problem aligning bolt holes. You may be able to drill through from the back side, or make some centering pins to mark where to drill.
Some bolt holes could also be moved 6" one way or another at the point of overlap between the two boards.
Get a plan, and all your ducks in a row before starting, and you should be fine.
Actually, I really like ratchet straps. You could also hold your horizontals in place with ratchets. One strap for the back beam, and one for the front.
Leave the tree for posterity!!!
OP
RobertEH
Silver Member
I will try to get a photo (since it is not my place, I can't just saunter out and get one!)
At this point, I concur with everyone, we don't want to remove any of the old truss and that is not in our plans. Just re-enforce it and sister it together - adding two more 2x10's to the cord, and putting a 4x4 post under the wall edge of the cord where the former 2x6 failed. Keep it simple and as was said in an earlier post, kick the can down the road until he can have someone qualified look at it!
At this point, I concur with everyone, we don't want to remove any of the old truss and that is not in our plans. Just re-enforce it and sister it together - adding two more 2x10's to the cord, and putting a 4x4 post under the wall edge of the cord where the former 2x6 failed. Keep it simple and as was said in an earlier post, kick the can down the road until he can have someone qualified look at it!