Contractor Talk - Professional Construction and Remodeling Forum banner

Ridge Beams and Collar Ties

10K views 12 replies 8 participants last post by  Burns-Built 
#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/
 
#6 ·
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?
 
#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.
 
#12 ·
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:
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top