# 2x4 ceiling joists?



## Pierrel'Ami (Mar 5, 2012)

This is my first post so go easy on me.

I would like to know if I can use 2x4's for ceiling joists for a 10' span instead of 2x6's ? I have a garage with a open ceiling height of 16' and I'm building an office 10' by 10' with a ceiling height of 10 feet. The space on top of the ceiling will be used for storage. So what I'm really asking is this. Is it legal and safe to use 2x4's for this ceiling? I will be using drywall on the ceiling.
Thanks.


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## joecaption (Nov 30, 2011)

Not even close.
http://www.awc.org/calculators/span/calc/timbercalcstyle.asp


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## jklingel (Dec 21, 2008)

To reinforce what Joe said, set a 2x4x10' on a block on each end and walk on it. I think you'll find it a little spooky. You could maybe squeek by w/ them, but the cost savings is trivial, if that is the issue.


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## joecaption (Nov 30, 2011)

Even with no top loading like you plan to do it will not work. sagging screw pops, cracked joints in the drywall.
Your going to need 2 X 10's 16" on center.
Just cut the tops of the joist at the same angle as the roof pitch.


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## Gary in WA (Mar 11, 2009)

Only if you used Southern-pine, SS grade or #2 at 12" o.c.: *TABLE R802.4(2) CEILING JOIST SPANS FOR COMMON LUMBER SPECIES (Uninhabitable attics with limited storage, live load = 20 psf, L// = 240)

*Here, if under this code: http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_8_sec002_par023.htm

Gary

P.S. Welcome to the forums!


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## Yoyizit (Jul 11, 2008)

It also depends on your O.C. spacing.

Can you take some load off your office ceiling by running struts to your garage ceiling?


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## AtlanticWBConst. (May 12, 2006)

Pierrel'Ami said:


> This is my first post so go easy on me.
> 
> I would like to know if I can use 2x4's for ceiling joists for a 10' span instead of 2x6's ? I have a garage with a open ceiling height of 16' and I'm building an office 10' by 10' with a ceiling height of 10 feet. The space on top of the ceiling will be used for storage. So what I'm really asking is this. Is it legal and safe to use 2x4's for this ceiling? I will be using drywall on the ceiling.
> Thanks.



For "Storage Use", full span of 10' and un-supported = No

Some information: 

http://www.awc.org/calculators/span/calc/timbercalcstyle.asp

http://www.askthebuilder.com/B124_Floor_Joists_Table.shtml


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## Red Squirrel (Jun 29, 2009)

I would go at least 2x6. But if you really must use 2x4 because of some clearance issue or something, set them on every 8" instead of 16". I don't know about the legality of that though.


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## M3 Pete (May 10, 2011)

Red Squirrel said:


> I would go at least 2x6. But if you really must use 2x4 because of some clearance issue or something, set them on every 8" instead of 16". I don't know about the legality of that though.


I'm with you. Even 2x6 at 10 feet is going to flex a bit. 

And finding the right species of lumber in the right grade as GBR suggests might work seems like tempting fate. Too close to the limits. 

The lumber costs are pretty minimal to upgrade to a 2x6, in the overall cost of building out an office.


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