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Old 02-27-2011, 12:44 PM   #1
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sistering joists

I recently bought a house with a 2 story detached garage. It's clear there are some issues with this space as the ceiling height is low and the home inspector said not to store anything on the second floor.

A garage door opener was installed (which I will be removing) and to fit it in the previous owner cut notches in 5 of the ceiling joists to accommodate the rail of the opener. The joists are 2x8 with a span of 20 feet; 24 inches on center. The notches are 2-3 inches wide and about 5 inches in depth.

In addition the 2 x 4 framing studs are 24 inches on center.

Any ideas on how to stabilize the notched ceiling joists and make the second floor more stable to be able to use as storage? I thought sistering the joists would create the stability I need.



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Old 02-27-2011, 01:20 PM   #2
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The cut joists are pretty much useless now with 5" of depth lost. Our resident Engineer may give you a "fix" for them. Doubling the others, if #2 SPF (spruce, pine, fir) @2'o.c., 20' span will give you 40# per sq. ft. for storage. Using Df/larch, #2, will support 56# per sq. ft.

I would reuse the existing, removing/replacing them at same time, after moving them higher to clear the openers back-set height. Do not remove all at once, walls may move, roof may fall. 1/3 up is the limit on rafter ties;

Re-nail the rafter/ties per suggestions, last table- bottom of page AND the “Heel joint connection adjustment factor” for the elevated rafter height above the wall;

Alright, I re-read and noticed -- 2-story-!!! This won't work, obviously...

Need to get a low-clearance track for the back-hang and a jamb opener, not overhead. How much room do you have over the garage door/rafter tie?



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Old 02-27-2011, 02:34 PM   #3
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jeese luise that a big span. If you could add another joist between every joist and double the cut ones it would certainly help, but its still not up to par. i would do that and add a lvl in the center of the floor span under the joists or if you don't have the overhead clearance, cut them and slide the beam between the joist and put hangers on them.
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Old 02-27-2011, 04:23 PM   #4
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Max length for a 2x8 floor joist is around 11'. 2x10 is about 16'. Based on materials. Fixing the notched joist still will not make the second story usable.

Best option is to support those joist so you can cut them down the middle and install a beam (double or tripled up 2x10s) you can attach them to with joist hangers.


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Last edited by dtsman; 02-27-2011 at 04:27 PM.
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Old 02-28-2011, 12:46 AM   #5
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Load carrying capacity of a wooden "beam" varies inversely, approx, as the cube of the length. That is why people are recommending cutting the span in half w/ a beam; 8x the load carrying. Whoever cut 5" notches in 2x8s was clearly not thinking clearly at the time.
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