Need help with ceiling joist issue

[timcali]

Hi guys. I have a bit of a problem. I have a detached garage from the early 1950s that I'm trying to convert into a workshop. It's a simple hip roof design, nothing really unique there.

I'm trying to create a ceiling so I can hang some drywall and fluorescent lights. I ran into a problem with the top plate. See the attached picture.

I need to span about 19'. If I'm looking at the span tables right, I can use Douglas fir 2x8 if I'm not planning on using the attic for storage. But the problem now is, the clearance between the top plate and the rafters is only 3 1/2". If I'm reading local code correctly, I'm only allowed to taper 1/4 of the width of the joist at the edge of the top plate. Which means a max taper of about 5 1/2".

Anyone know what I can do here? I'm in talks with a few structural engineers. But I'd like to weigh my options before spending a ton. I've even considered a drop ceiling, but all installs I've seen use ceiling joists. I'd have to hang it from the rafters somehow, and I'm not sure that's legal per code either.

 

[gscallon]

I'm not sure what's legal where you are, and I realize the span tables wouldn't encourage it, but my garage ceiling is 19' wide with 2x6s going across on 24" centers. There was a drywall ceiling and lights hanging from them but I wanted attic storage too. I glued and screwed vertical ties about 4' in from both sides on every joist. The ties went from the joists, straight up to the rafters. I also added collar ties about a foot down from the peak, on every set of rafters. I then screwed 1/2" plywood decking over all of the joists and the thing is solid as a rock. Where I could get it to bounce pretty good with my weight (180lbs) before, it's now super solid. My storage height is only about 3 feet to the peak, so I can't put a lot up there, but I'm really happy with how it all worked out, even with the 2x6s. If you want more details, let m know.

Regards,
-Greg

 

[The Customer]

Greg,

Your correct on the tapper if you don't attach the ceiling joist to the rafters. If you can marry the joist along side the rafters and nail the two of them together, you should be able to cut them to a point if you'd like. By nailing them to the rafters, you essentially support the ceiling joist top and bottom. With a hip roof you'll have to stop the last ceiling joist back 4 ft from both ends and nail perpendicular 2x4s to that ceiling joist and out to the rafters running the other direction.

 

[Beemer533]

Regarding drop ceilings, there is no need for joists.. You would just need more wire to hang the ceiling from the rafters.

 

[Cyberbear]

If you notch the bottom of the 2 x 8 enough to set on top of your dbl. plate and use metal brackets when tying to your stud wall, it should take care of your problem.

 

[timcali]

Thanks for all the replies. There are a few ideas here I can run with. Another guy I talked with suggested a ledger board mounted around the perimeter, then use joist hangers. Similar to a deck or pergola. I have a contractor coming out today to give me an estimate. I'll see what he has to say.