# lumber dimensions



## Will (Jul 1, 2006)

I posted a reply about this but nobody saw it so I'm making it a new topic. I'm building that garage addition. my remaining questioons were as follows:

As it happens I just talked to her and the ceiling is only 12 feet from the basement floor, 9 feet from the house floor level. the ceiling of the garage I mean. so basically the question of space on top is moot, I thouight the garage ceiling was a lot higher. But the garage ceiling is the same height as, ie level with, the the house ceiling which makes sense. So basically the whole space is gonna be enclosed. when you say: "forget the firewall" what do you mean. as in I dont NEED a firewall or I cant build a firewall or what? 
So now I guess the idea of notched studs so I can have a celing comes back into play. But then again, do you think the studs really need to be connected to the existing garage ceiling? what If I just still did it the other way, had complete walls with top plates, and then joists on top (ceiling joists) and the joists would either contact the ceiling or be like an inch from it. so the ceiling in the rooms would be like 8 inches below the house level, but the whole thing would be enclosed and there wouldnt be a need to hassle with notches and things.
also one more thing. I was talking to my half brother whos a carpeneter and he said he thought those 2x4 walls one of you (inspector I think) recommended on which the floor joists would rest wouldnt be quite strong enough. He recommended the studs being more like 2x6 down there. any thoughts on this? 
Also do you think only the sole plate needs to be PT or the whole wall (the whole wall under the floor)?
I guess the general question is: is there any ADVANTAGE to having the wall connected to the garage ceiling? or could it just be enclosed ( maybe even qith 2x4 joists on the top so it would be even closer to the existing ceiling.
           Thanks, 
                     Will


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## Square Eye (Jul 1, 2006)

Go back and look Will;

http://www.houserepairtalk.com/showthread.php?p=3916#post3916


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## Will (Jul 3, 2006)

Sorry I didnt realize there were two pages. Thanks for that reply. now, you say that if the rooms dont fill the whole space, Ill have to have a firewall. Do you mean that even if the studs go floor to ceiling, but the ceiling is lower than the garage ceiling, I'll have to have a firewall? Anyway, what exactly is the logic of that? Don't quite get it. How would whether the studs are connected to the ceiling have any bearing on what happens if there's a fire?

                                                                      Will


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## Square Eye (Jul 3, 2006)

If there is not a continuous firewall from floor to ceiling, the fire can spread to the ceiling joists over the addition.

A firewall is a protective barrier to protect the framing members from the flames. If there is any exposed wood, fire will spread. A firewall also has to have at least one coat of joint compound and the joints taped. The easiest way to seal the framing is to run the wall from floor to the ceiling.


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## Will (Jul 6, 2006)

Wouldnt you have to have a fire CEILING then too?


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## Square Eye (Jul 6, 2006)

Is there a finished ceiling in the garage? 

If there is, then yes, the ceiling becomes part of the firewall or barrier.

If not, then the firewall is supposed to run all of the way to the roof decking.


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## Will (Jul 6, 2006)

yeah there is a sheet rocked finished ceiling in the garage. I'll be taking the sheetrock off most probably because I'll need to get at the rafters to attach studs and whatnot to them. I think I see what youre visualizing - youre thinking of like exposed gbarage rafters and stuff. No its no like that, its sheetrocked all the way already. Are you saying I should re - rock the ceiling with the 5/8 fire retardent stuff in that case?
       Also I was wondering - do you think I can go 2 feet on center with all the studs, rather than 16 oc? it would save on materials and labor, and not only that, Id be able to notch the studs like you were saying and put the ceiling joists in. 16 oc ceiling joists seems a bit numerous. But 24 oc is what I was planning to do the floor joists with anyway so if I had the studs at that too everything would be uniform and I could just attch the ceiling joists at 24 oc to the studs. I guess in a house youd probably want 16 but since this is oinly an addition I was wondering if maybe I could just do the 24 oc.

                                                                     Will


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## Square Eye (Jul 6, 2006)

You'd better put the floor joists and the wall studs on 16" centers.

Go above the ceiling and lay 2x4s, cut tight, between the ceiling joists, directly over the wall. Then you will have no reason to tear any of the ceiling down. Just nail your top nailer plate through the ceiling into the 2x4s.

If the garage ceiling is the same level as the house ceiling, then why are you going to frame a new ceiling? Why not just use that existing ceiling?


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## Will (Jul 6, 2006)

_Good point_. About not needing to frame a new ceiling. Thanks for the quick reply there too. I guess you happen to be online right about now. I don't really get what you mean about "go above the ceiling and lay 2x4s cut tight in between the ceiling joists." Do you mean try to access it from above so I don't have to rip off any sheet rock? i'm not sure I can access it from above. You meant if I can get up behind the sheetrock I can nail or screw in 2x4s to nail the top plate of the wall to, and then nail right through the sheet rock to those 2 x 4s? The ceiling joists will be there under the sheet rock anyway, why couldnt I just nail to those? Course depends which wall were taloing about, the two side walls and the central partition wall ( dividing the entire area into 2 rooms) will be parallel to the ceiling joists of the garage and the house, while the fire wall touching the house wall and the front wall will be perpendicular ( to the best of my knowledge, Ive only been there once and looked at it rather breifly). So seems to me if I can line up the side walls with one of the rafters ( ceiling joists, whatever) up above, that could be my nailer for the wall's top plate. on the front and baclk walls I could go up against those perpendicualrly, nail to each successive rafter. Is this right or were you suggesting something else that I'm not understanding?
     Also, by the way, now youre saying I should make the FLOOR JOISTS 16 oc? I thought 2 foot centers were plenty for that. Damn at this rate i'm gonna have to do a whole new drawing of this thing. Why the 16 centers for the floor joists? arent floors usually at 2 foot centers?

Just so I get all these questions answered:
1. you mean access ceiling joists from above somehow and put nailers up there and nail THROUGH the sheet rock without taking any of it down?

2. If so why not just use ceiling joists as nailers?

3. Why do you suggest the 16 inch centers for the joists?
                                                                         Will


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## Square Eye (Jul 6, 2006)

Parallel walls directly under the ceiling joists will do fine. Nail into those on your parallel runs and try to hit the other joists on the other walls where you can.

If for some reason you could not run directly under the joists, then I would recommend the blocks between the joists.

I think you're going to make it Will.


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## Will (Jul 6, 2006)

Hi
_Dang_ right I'm gonna make it!  OK OK maybe I'm asking too many of these detailed questions. Comes time when youi gotta just go ahead and trust your gut and your experience. But still, do you really think I gotta go 16 on center with everything? Thats the one thing thats bugging me now. 

                                                                 Will


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## Square Eye (Jul 6, 2006)

Plywood and drywall are designed to bear loads per certain criteria.

Part of that criteria is span per framing member. Code also specifies span. 

24" is acceptable for ceilings and roofs where there is USUALLY no more load than it's own weight. Floors and walls are exposed to traffic daily and require shorter span distances. Drywall on 24" centers will flex enough to crack at the joints when a person leans against it. Floors will sag and begin to crack when exposed to traffic on 24" centers. Say you have a warped stud in the wall. 24" centers will magnify it much more than 16" centers because of the lack of integrity and unity in the construction. Every stud helps the next just like the spokes in a bicycle wheel. 


Zen, Ying and Yang,, Mang


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## Will (Jul 7, 2006)

hunh ok. But decks arent always 24 on center, are they? but then again they have like 5/4 4 deck boards.


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## Square Eye (Jul 7, 2006)

Any deck I build has joist 16" on centers.


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