adding garage ceiling joists


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Old 10-16-06, 10:44 AM
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adding garage ceiling joists

Hi folks, thanks for taking the time to read my question (and hopefully respond).

I have a 38' x 22' detached 4 car garage, which has no ceiling, and I would like to install a drywall ceiling. It has no ceiling joists at present, just 48" o.c. 2x6 collar ties running the "short" way. I would like to add ceiling joists running the same way. From the span tables I checked, to be able to run that 22' span, support the drywall (possibly two layers, for soundproofing), and a little storage above, I would be 2x10s.

My question is about installation: the 5:12 pitch roof drops to about 6" above the wall top plates, so the full 2x10 wouldn't fit there. Is my best option to:

1. notch out the ends of the 2x10s, so they are only 6" tall over the supporting walls?
2. bolt ledger boards to the stud walls, and attach the joists to the top (or edge?) of those ledger boards (did some searching, but didn't find a picture that shows how the joists mount to a ledger board)
3. mount the 2x10s to the tops of new stud walls, framed an inch inside the existing walls (planning that anyway, since half of the garage will be converted into a home theater / music studio)

Here are a couple pictures:

http://www.horstkotte.us/htpics/roof%20construction/IMG_0004.jpg

http://www.horstkotte.us/htpics/roof%20construction/IMG_0005.jpg

Thanks...
 
  #2  
Old 10-17-06, 06:24 AM
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Joists

Can the collar ties be used as joists also? How are the collar ties installed? A picture of the area where the roof and wall meets would be helpful.
 
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Old 10-17-06, 09:15 AM
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Originally Posted by Wirepuller38
Can the collar ties be used as joists also?
I doubt it, they are only 2x6, over a 22' span, and just 48" o.c. My understanding is that they are just enough to keep the weight of the roof from pushing the walls apart.

Originally Posted by Wirepuller38
How are the collar ties installed? A picture of the area where the roof and wall meets would be helpful.
Here are a couple pictures (can't figure out how to enable the IMG tag in this forum):



 
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Old 10-17-06, 05:12 PM
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Since your building another wall inside the other one, the best solution would be to set the 2x10's on top of the studs. The other methods would be very difficult and would probably couse some problems down the road. You should probably use framing anchors as well as nailing it to the top plates of your new wall. Make sure you have double top plates. Good Luck
 
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Old 10-17-06, 07:40 PM
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You said about 6" above the top plate. If you come up 5-3/4" from the bottom of your 2x10, that would leave you with 3-3/4" down from the top of the 2x10. Come over from the top 9" and you’ll have a small 3-3/4" x 9" triangle to cut off from the top of each 2x10.

Once you do that you can put them in on angle with the top up against the rafter and moving the bottom into place. It's a lot easier that way. You have to make sure no roofing nails are in the way that stick below the sheathing. If there is just clip the point of the nail off before you do this.

After you install these you have to put two rows of strong-back on with a 2x4 flat and 2x6 on edge. Maybe your code might want something different. I do this type of work all the time.

There's no need to frame new walls in front of the existing walls or bolt a ledger unless there's something wrong with your existing walls.

Framing new walls is way more work labor and material and bolting a ledger is also more work and material and then you have to bolt the ledger and hang all your joists with joist hangers. Joist hangers are used all the time and work but that’s when you have no choice. Here you have a choice and joist hangers are added work for no reason.
 
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Old 10-17-06, 07:45 PM
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Joe:

Please read #3 of his original letter. He is already planning on building another set of walls since he is going to make a home theater & music room. Thats why I said to put them on top of the new wall.
 
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Old 10-18-06, 06:01 AM
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Joists

Cut the ends on angle same as the roof pitch and set on top of the existing wall. Place all between a pair of collar ties before any of them are nailed.
 
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Old 10-18-06, 02:19 PM
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Originally Posted by Jack the Contractor
Since your building another wall inside the other one, the best solution would be to set the 2x10's on top of the studs. The other methods would be very difficult and would probably couse some problems down the road. You should probably use framing anchors as well as nailing it to the top plates of your new wall. Make sure you have double top plates. Good Luck
Thanks Jack!

I'm kind of waffling between putting the joists on the new walls vs. the existing walls - if I do the former, I get extra benefit of acoustic decoupling for the ceiling, since it wouldn't be attached directly to the outer shell of the garage; if I do the latter, however, I can put in the joists for the entire garage, and put up drywall ceiling throughout, which would be nice (although of course more expensive, since twice as much material). If I did the latter (on existing walls), what are some of the problem down the road you allude to, that I'll need to look out for?
 
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Old 10-18-06, 02:26 PM
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Thanks Joe!

So those would be perpendicular to the joists, on top, spaced at thirds of the length of the joists, to keep the joists even vertically, and keep them from twisting?

The new walls are going in on half of the garage (the part being finished), to cover a concrete back wall, and lower stem walls on the other outside walls - this will give me soundproofing (acoustic decoupling), cover lower stem walls that protrude from the existing studs, and ability to place outlets on lower wall where I can't now (concrete block lower back wall).

Thanks again...
 
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Old 10-18-06, 02:31 PM
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Originally Posted by Wirepuller38
Cut the ends on angle same as the roof pitch and set on top of the existing wall. Place all between a pair of collar ties before any of them are nailed.
Thanks Wirepuller38!

Not sure I follow you on the last sentence - did you mean just get them all up there initially, so I can make sure they're spaced out evenly between the collar ties, before I start fastening them?

Also, I have these corner braces right below the collar ties in all 4 corners of the garage. Can they be removed once the joists are in, or moved higher, so I can mount drywall to the bottom of the joists?
 
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Old 10-18-06, 03:14 PM
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Originally Posted by gubgub
Thanks Joe!

So those would be perpendicular to the joists, on top, spaced at thirds of the length of the joists, to keep the joists even vertically, and keep them from twisting?

The new walls are going in on half of the garage (the part being finished), to cover a concrete back wall, and lower stem walls on the other outside walls - this will give me soundproofing (acoustic decoupling), cover lower stem walls that protrude from the existing studs, and ability to place outlets on lower wall where I can't now (concrete block lower back wall).

Thanks again...
Yes, the strong-backs are perpendicular to the joists. If I were you I would still nail the joists to the existing top plates and then frame any walls you want under them later.

Plus it helps tie your roof in better and it's also saving you on putting solid blocking on every joist later on if you were to sit them on new walls. You would have to do that so that it acts like a box/band joist.

Are you planning on putting pull down stairs in the home theater section?
 
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Old 10-18-06, 04:26 PM
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Originally Posted by Joe Carola
Are you planning on putting pull down stairs in the home theater section?
Did you mean for access to storage above the joists? If so, no, but I'll do that from the garage side.
 
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Old 10-18-06, 04:58 PM
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Originally Posted by gubgub
Did you mean for access to storage above the joists? If so, no, but I'll do that from the garage side.
If you do that, since your garage attic will be the same as your home theater attic, you’re not aloud to put attic stairs in a garage around my area unless you have fire rated attic stairs put in. That’s even if they make them where you’re from.

Or you have to build a fire wall that separates the garage attic to the home theater attic and also if your garage is attached to your house to have to put a fire wall against your existing wall to protect your existing house or attic.

The last job I did where the garage was attached to the existing house, I had to frame up a gable wall and the sheetrocker had to install two layers of fire proof sheetrock on that wall to separate the garage attic and existing.

You have to check with your building department or Architect for this.
 
 

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