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amp2oo1 07-30-2012 06:12 PM

20x22' detached garage ceiling joist advice
 
Hello all. Signed up when I bought my house hoping to jump right into the garage, which didn't happen at all. 4 years of updates to the actual house means I can finally start on the garage. It already has new siding, gutters, and shingles. Now that I'm tackling the inside I'm wishing I had just knocked it over, but hindsight is 20/20 so I'll make the best of what I have in my starter house.

The goal of the garage will be simple OSB walls/ceiling (R-19 KF is what I'm currently leaning toward unless otherwise educated), piped conduit wiring, and possibly a future heater (gas is already run out to garage). No plans to store anything in the garage attic, but the option would be nice.

Construction (currently):
  • 2x4" stud walls, 24" OC
  • 2x6" ceiling joits, 24" OC with 2x4" tied in perpendicular for the last 5-6 feet
  • 16' wide by ~6.5' tall garage door - old, rusty, springs of death - this must go

Questions (feel free to tell me my thoughts are completely wrong, I won't be offended!)
  1. Is 1/2" OSB ok for the walls and ceiling (or do I need 5/8" OSB for ceiling) (assuming a sound structure to which it can be fastened)?
  2. Do I need to get a (or a couple) glulam or LVL beams that span the garage length, and tie in 2x6" or other sized lumber 24" OC perpendicular to said beam with cross braces between them? Or something different entirely? I am not attached to the current "joists" that are in there and am willing to pull all that out and do it right.
  3. Can I sister the existing 2x6s with another 2x6 across the entire span?


Current pictures as of today (note that the left over wiring you still see will be ripped out 100%, and the garage door sensors will be properly fixed with the new door. I'm the only person with the opener with no pets or kids, and I only open the door to take the car in and out)

http://i114.photobucket.com/albums/n...e/IMG_3423.jpg
http://i114.photobucket.com/albums/n...e/IMG_3422.jpg
http://i114.photobucket.com/albums/n...e/IMG_3421.jpg
http://i114.photobucket.com/albums/n...e/IMG_3420.jpghttp://i114.photobucket.com/albums/n...e/IMG_3418.jpg
http://i114.photobucket.com/albums/n...e/IMG_3417.jpg
http://i114.photobucket.com/albums/n...e/IMG_3416.jpg


Garage door guy came today and gave a quote but I need to sort out my joist mess and sheet the walls (hopefully) first.

I appreciate your time and any advice you can give!

joecaption 07-30-2012 06:23 PM

Why OSB and not sheetrock? You may find it's required by code for fire resistance.

amp2oo1 07-30-2012 06:36 PM

Quote:

Originally Posted by joecaption (Post 977825)
Why OSB and not sheetrock? You may find it's required by code for fire resistance.

I like the utility aspect of OSB better (hang stuff easier, less likely to damage, etc). I also don't want to have to finish the drywall. I understand the OSB sheets are about 2x the cost of sheetrock, but I think the cost of finishing that based on some quotes I received would offset the money saved. I'll just paint the walls white/grey to brighten it up and be done with it.

I will consult the local building inspector this week on the fire resistance aspect. I thought since it was detached I was in the clear, but best to check.

GBrackins 07-30-2012 08:49 PM

is the garage attached to the dwelling?

amp2oo1 07-30-2012 08:49 PM

Quote:

Originally Posted by GBrackins (Post 977916)
is the garage attached to the dwelling?

No, it is detached.

GBrackins 07-30-2012 10:01 PM

I asked because most building codes require gypsum board on the wall that separates the garage from the dwelling. if not attached should not be an issue, but please verify with your building department as codes can vary from place to place.

cleveman 07-30-2012 10:51 PM

Looks like you have a hip roof and your sidewalls are only 7' tall or so.

I would seriously consider raising the building up and putting 2 courses of concrete block around the perimeter first.

I don't think you mentioned your location. That always presents a challenge.

As for the framing, I have spanned 24' with 2x8's every 2' oc with solid wood blocking every 8'. I then hung sheetrock on the ceiling and I don't have any noticeable sag. OSB will be lighter.

I suppose you can span 20' with 2x6's. It won't collapse, it will sag first. I would use 2x8's next time. I think the solid wood blocking will help a lot. You could put it in the 22' side at about 7'-4".

cleveman 07-30-2012 10:54 PM

Oh, I see you in the State Penitentiary there in Joliet.

Even if your garage is not on footings, you can raise it up another 16" with 2 courses of block. They will crack a bit if you're not on footings, but it won't be too bad.

amp2oo1 07-31-2012 09:52 PM

Correct, walls are only really about 7' to 7.5'. Raising the garage would be nice, but that is too much of a task for me honestly. Many of the garages in this neighborhood are this way, not that it makes it any better, but at least I'm not an oddball.

I can/will rip out the existing 2x6's, and can replace with 2x8" (or whatever else, ultimately).

When you say solid wood blocking every 8', does that mean ~2' pieces that tie the 2x8" joists together in a perpendicular fashion?


A coworker today suggested an LVL beam perpendicular to the cars (so it doesn't tie into the header for garage door). Add 4x4 posts attached to the walls, attach beam, then run 2x8" from the beam to the top plates of the walls using hangers. Seems easy enough (on paper at least:laughing:), but not sure if overkill. I'm ok with a little overkill, though.

Mr Inspector owes me a call back on the OSB being up to code thing.

Thanks for your input/advice!

cleveman 07-31-2012 10:27 PM

Regarding the solid wood blocking, just measure the inside of the building and divide that by three, then snap a line down those marks. Cut a bunch of 2x6's to whatever the distance is between the rafters. You may have to cut them individually because this will vary. Then screw them up there on alternate sides of the snapped line.

This will really stiffen your framing and you will be able to hang some deer up there to dress out.

Regarding the LVL, I wouldn't worry about it. I think your framing will hold up an OSB ceiling.

It's not a big deal to raise the garage. I once raised a 28 x 50 something building 4' with just 2 hi-lo jacks and a covey of car jacks.

amp2oo1 08-01-2012 09:44 AM

Quote:

Originally Posted by cleveman (Post 978733)
Regarding the solid wood blocking, just measure the inside of the building and divide that by three, then snap a line down those marks. Cut a bunch of 2x6's to whatever the distance is between the rafters. You may have to cut them individually because this will vary. Then screw them up there on alternate sides of the snapped line.

This will really stiffen your framing and you will be able to hang some deer up there to dress out.

Regarding the LVL, I wouldn't worry about it. I think your framing will hold up an OSB ceiling.

It's not a big deal to raise the garage. I once raised a 28 x 50 something building 4' with just 2 hi-lo jacks and a covey of car jacks.


Do you have any links to pictures of what you are describing? I'm having a hard time picturing it in my head.


Mr Inspector just called and said OSB (or other plywood) sheeting is acceptable for a detached garage.

cleveman 08-01-2012 10:13 AM

Try to imagine it on a floor system, then pretend you're in the basement.


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