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Old 07-30-2007, 01:16 PM   #1
Joe Wongananda
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I am planning on putting up a pull up bar in my garage. I currently have straps going over the rafters and I plan on making something more permanent.

My problem is that I just discovered a crack in one of the joists at the bottom of a rafter. The garage is at least 50 years old.

This is the crack:
http://www.crossfit.com/discus/messages/26/45274.jpg

The joists are 2x4's, they are about 15' long, and are about 24" apart.

I was planning on sistering the cracked part of the joist, but my question is would it be better/stronger to run a new 2x4 sister the whole length of the span vs. just part of the span? I was just going to do a 3-4' section, but I don't know enough about construction/engineering. I also figure that someone here would know what woulld be suitable for kipping pull ups.

I am 140 lbs and don't want to have the roof cave in on me. I plan on mounting the bar perpendicular to the joists to help spread the load over several joists.

Any recommendations are appreciated.
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Old 07-30-2007, 01:23 PM   #2
Paul Findley
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I would say that a 15' 2x4 is a minimal rafter, unless it is an engineered truss, which it probably is not.

You may want to consider something different for pullups.

To repair that crack, I would replace the whole piece.

(Message edited by paul on July 30, 2007)
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Old 07-30-2007, 02:02 PM   #3
Mitch Hamm
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Your picture is not big enough to see how the rafter/joist system is built, but keep in mind that the joist is there to resist the thrust at the heels of the loaded rafters. That means the joist is in tension. It is not meant to take a point load like the one your storage container is putting on it. An effective repair would "set" the joist back into the pre-broken location and then sister it. I would cut an 8' 2x4 in two and sandwich the break.

As for your pullup bar, I would tie four joists into the load with another 8' 2x4 or 2x6 running perpendicular to the joists and get the bar as close to the wall as possible while still allowing you to pullup.
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Old 07-31-2007, 01:11 PM   #4
Chris Jordan
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Sister the whole length. It looks like the garage was built to support something less than a small block chevy on a chain hoist. You may consider engineering a little more strength above your pull-up bar before kipping away while wearing a 50# vest. Maybe tie some braces into the rafters above to help distribute the weight a bit. Also, support your pull-up bar across several rafters so you aren't shopping for a new weakness. I put two 2x6s across the top of my rafters and screwed my pull-up bar to that.
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Old 08-01-2007, 06:38 PM   #5
W. Geoffrey Miller
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That's definitely solid construction and not the lightweight junk I'm used to seeing built these days. The decking on that garage roof actually looks like 1" x 6" T & G planking versus the OSB that's being installed nowadays. Heck, I bet there's even a real ridge pole running the width of the roof. :biggrinthumb:

I agree with what Chris said - sister the whole length and you should be good to go. When mounting the bar, as is always good engineering practice, try to distribute the load across a number of chords instead of just one or two. Most often times concentrated loads are the cause of failure.

Good luck!
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Old 08-04-2007, 07:54 PM   #6
Joe Wongananda
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Thanks everyone for the suggestions.

I am hoping to get out to the hardware store in the next few days. I plan on sistering the whole length of the joist.
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Old 10-23-2007, 01:09 PM   #7
Jerry Glaeser Jr.
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Re: Rafter repair for garage pull up bar

I would use gang nails on either side of the joist to give it some solitary strength and then use a sister board over it for the full length.
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Old 10-23-2007, 02:41 PM   #8
John Edmondson
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Re: Rafter repair for garage pull up bar

In my opinion (I'm a carpenter, take it or leave it), even if you sister the broken joist with another 2x4, it will deflect (bounce) quite a bit once you start kipping. I would run your pullup bar acros 3-4 joists and sister them all with at least a 2x8, maybe even a 2x10. Minimum deck framing in this area, for a span of 15', calls for 2x10's on 12" centers. I believe kipping poses a live load/stress on a floor/ceiling similar to foot traffic. Plus I just like stuff really solid. My $0.02
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