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Old 08-04-2008, 10:07 PM   #1
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Extending a ceiling joist?


I'm remodelling a 1926 bungalo, and will be moving a load bearing wall 3 feet. Currently a wall evenly divedes the 29' space into two 15' sections, and 16' joists extend from the end walls to this support wall. When I move the wall, one set of joists will be supported at 12', with a 4' tail hanging over, while the other set of joists will be about 2' short.

I'd like to scab on an extension if that is possible. I can certainly tie the two opposing joists together where they overlap in the middle of the space, but I'm sure I'll need more strength than that. The attic above has a 3/4" douglas fir deck, but will have no load, except for the occasional maintenance person installing a cable TV feed, looking for a leak in the roof, or chasing a rogue squirrel. It should be strong enough for that occasional load, but otherwise it will just be holding up the drywall on the ceiling.

Is there a calculator that will let me explore how long appropriate scabbing should be, and how it should be nailed? The wood in this place sure beats what you can buy today, so I'd like to preserve every piece that I can.
Thanks,
Clif

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Old 08-04-2008, 11:53 PM   #2
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Extending a ceiling joist?


I won't say it isn't possible, but it isn't likely and it is not a good idea. Splicing one or two is one thing, but an entire ceiling system isn't a hot idea. It is sometimes done, but only with an engineer's design. There's no online resource (or any other resource for that matter) that will guide you in doing this in a safe compliant way. You really need to consult a structural engineer.

You might look into the possibility of installing an upset LVL or PSL beam where the wall is now to support the ceiling joists. If it is upset into the ceiling, it would not show. Joist hangers on each ceiling joist would attach them to the beam. You'd of course have to provide solid bearing at each end of the beam. A good lumber yard can provide the design calcs for the spans you're supporting and can recommend the size of the beam.

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Old 08-05-2008, 08:46 AM   #3
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Extending a ceiling joist?


Thanks! I had a feeling it was a stretch. And above all, I don't want to be the focus of a future inquiry from the next homeowner who complains about a weak ceiling, and about some fool who took such a shortcut. If I'm going to do it, I've got to do it right.
I will contact a structural engineer for some advice.
Thanks for the straight talk.
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Old 08-05-2008, 08:58 AM   #4
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Extending a ceiling joist?


Engineers can sometimes come up with scabbing miracles, using long sistered scabbed members, glue, and tons of nails. Hopefully you'll find one that can help you out. Let us know how it comes out!
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Old 08-05-2008, 05:32 PM   #5
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Extending a ceiling joist?


Quote:
Originally Posted by thekctermite View Post
Engineers can sometimes come up with scabbing miracles, using long sistered scabbed members, glue, and tons of nails. Hopefully you'll find one that can help you out. Let us know how it comes out!

A++ advise above
LOL, yes they can.

If house is off grade and most were back then.
1926 center support floor joist beams hmmm.. I've seen them with tiny piers 10' to 12' oc.

You might want to ask the engr to take a peak below and see if there is anything you should do. sounds like you are shifting some load off the top of the beam. (but, I'm in FL looking at a computer screen)
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Old 08-06-2008, 09:40 PM   #6
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Extending a ceiling joist?


Thanks, Bob. Will do.
I did go underneath and it looks like the floor is pretty well supported. My load bearing wall is not going to shift the load between the various floor supports very much. Nevertheless its good to have an expert take a look.
Frankly, its always scary to look at something new, as you often discover something you wish you hadn't... like when I removed the plaster from the ceiling in one room and found mushrooms growing on the composted joist right below a leak in the roof. What fun it is to work on a house!

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