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Civil / Structural PE
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88 Posts
Discussion Starter #1
Ridge beam, shmidge beam. Who needs them?

And, aren't collar ties the answer for all sagging roof systems?

Those questions are among framers' most commonly asked. And also a hot offshoot of the recent post on over-engineering. As promised in that thread I dusted off the column I wrote a couple years back for NAHB addressing both questions and posted it on my home blog. I would have posted it here but it contains 6 sketches and this site only allows three per post. So look at it there and let's discuss it here. Here is the link directly to the article:

http://www.constructioncalc.com/blog/structural-design/collar-ties-and-ridge-beams/
 

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Superior Firepower
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5,089 Posts
Collar ties are frequently cut out after final inspection leaving the pinch rafters to spread the exterior walls. adding a snow load compounds the problem.
Ridge beams and Purlins are the benchmark of true professionals and quality engineering.
:thumbsup:
 

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Curmudgeon
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11,706 Posts
Collar ties are frequently cut out after final inspection leaving the pinch rafters to spread the exterior walls. ....
Who are these lumber thieves?
Why do folks let them roam around
the house?
 

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Super Moderator
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10,592 Posts
We often wonder about the installation of a lot of nails in a cramped area. I have seen truss girders that spec out nails every 4 inches. I have seen hangers that spread about 80 nails over about 1 sq ft. At some point, I am sure the nailing becomes detrimental to the truss. Of course thats why we have engineers to factor this in. My question is this: Is there a general rule as to the amount of nails per sq ft that can be used before it becomes detrimental to the framing member?
 

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Curmudgeon
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11,706 Posts
We often wonder about the installation of a lot of nails in a cramped area. I have seen truss girders that spec out nails every 4 inches. I have seen hangers that spread about 80 nails over about 1 sq ft. At some point, I am sure the nailing becomes detrimental to the truss. Of course thats why we have engineers to factor this in. My question is this: Is there a general rule as to the amount of nails per sq ft that can be used before it becomes detrimental to the framing member?
I'd be curious to know
how many engineers have heard
the term "sewing your nails."
 

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Super Moderator
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10,592 Posts
I'd be curious to know
how many engineers have heard
the term "sewing your nails."
Have you ever had the privledge of working with the new guy who nails like that?? Funny how those guys never seem to stick around very long. I do have one guy who has worked for me for 5 years who use to be an over nailer. Not quite that bad but he is much improved now.
 

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Superior Firepower
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5,089 Posts
Who are these lumber thieves?
Why do folks let them roam around
the house?
Weekend warriors up in the attic. Those floppy 1x6s are the first to go when building out for storage space.

I have seen truss girders that spec out nails every 4 inches. My question is this: Is there a general rule as to the amount of nails per sq ft that can be used before it becomes detrimental to the framing member?
Depends on the size of the framing member. 16d every 4" on the side of a 2X will often cause splitting. (for others who may not already know this)
 

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Curmudgeon
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11,706 Posts
Weekend warriors up in the attic. Those floppy 1x6s are the first to go when building out for storage space.
..........
Gotcha. :thumbsup:
But then we can't really prevent
them buying saws and drills and such.
They will be free to destroy their own
house no matter how you build it.
 
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Civil / Structural PE
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88 Posts
Discussion Starter #11
Here's the scoop on too many nails. The building code says something like, "Predrill nail holes to avoid splitting the wood."
Yeah right! Ha! In all my years I've never once seen a nail hole predrilled.

Of course the spacing at which splitting occurs depends on the thickness of the wood and moisture content. Bottom line: any engineer worth a hoot will not specify so many nails that the chance of splitting is even there. There are other options such as gussets, lag bolts, or SDS screws.
 

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Registered
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2,603 Posts
Can anyone tell me how to cram twelve 16d’s into the small overlap space where the top chord and bottom chord (ceiling joist) come together? I think if you tried, you’d massacre the wood so badly, none would be left to hold the nails. It is for this very reason that gang-nail plates were invented.
A couple of ways I've done it and had my engineer sign of on it but basically pywood gang nail gussets will do the trick. Sometimes i would scab a 2x onto the top chord /rafter about 4 ft long and then make a plwood gusset of 3/4 plywood about 3 ft on the long side and shoot about 40 8d's through the plywood into the bottom chord and 40 8's into the top chord... Sometimes i would just cut another bottom chord with the angle to fit the rafter/top chord and then there was no scabbing and my plwood gusset could nail directly into the top and bottom chord. Sometimes, because of lath, insulation , and or odd layout , i would cut a new bottom chord, with the angle to fit the bottom of the top chord/ rafter, but I would set the new bottom chord 4 or 6 or 10 inches above the original bottom chord/ceiling joist. Then i would nail my gusset again with 80 or more 8's. This setup would essentially be a tail bearing truss but they work fine too. Of course there is a few more steps to making an old rafter /joist roof into an engineered truss but as the article stated the connection at the outside bearing points are the most critical. ... My engineer has been designing trusses and structural roof repairs since the early 1960's and i have been doing structural roofs since the late 70's. So far no problems. I drive by them once in a while just to check.:w00t:
 

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Have you ever had the privledge of working with the new guy who nails like that?? Funny how those guys never seem to stick around very long. I do have one guy who has worked for me for 5 years who use to be an over nailer. Not quite that bad but he is much improved now.
Those guys will quickly rethink that over ambitious nailing once the screw it up and have to tear it apart! :clap: I was a kid once to...:whistling
 
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