Double 2x12 w/ 1/2" osb center span?

LeeB · January 14, 2016, 11:09:13 PM

I know it's not TF, but can anyone tell me what the max span for a double 2x12 with a 1/2" osb center, glued and screw (don't know the screw apttern, I'm not home) would be?

beenthere · January 14, 2016, 11:35:26 PM

A manufactured product, or is it homemade? What is the stress grade of the 2x10's ?

LeeB · January 15, 2016, 12:23:55 AM

BT,
It's home made and 2 x 12, not 2 x 10. #2 grade. A little more info. They are being used in a 20 x 40 equipment shed. The roof will consist of 2x6 purlins 16" oc with a galvalum roofing. The purlins will run the 40 ft length with the beams running the 20 ft length. Post spacing for the 40 foot will be 10 ft center giving me 4 bays. The intent is to have posts spaced 10 ft oc both ways. and I have no worries about this being strong enough. I just was curious about the maximum possible span. Also not sure if the OSB is 1/2" or 3/4" so I used 1/2" hypothetically. Like I said, I'm not home right now and the guys are building it while I'm gone, for the most part to my specs. The posts are 6x6 and all lumber is treated SYP.

beenthere · January 15, 2016, 12:58:13 AM

Typo on the 2x10.. and I think you will find the 2x12 plenty strong.

Don't know a max length... but if you want longer, then a deeper beam is where you will get more strength..

LeeB · January 15, 2016, 02:01:57 AM

Using Don's beam calculator, if I did it right, it should be able to span at least 20ft with our snow load which is what I wanted to know. I think I'll still go with just 10ft though. I want this thing to outlast me by a long time.

Peter Drouin · January 15, 2016, 06:15:42 AM

Stay away from the osb, it's junk, Go with cdx, I think for 10' your good.

LeeB · January 15, 2016, 06:23:55 AM

Too late Peter, they already did it. I didn't ask for it. I only told them double 2x12. They did want to know if I was going to park the dozer on top or under the shed.

beenthere · January 15, 2016, 09:18:42 AM

Some pics would help see what you are doing.. 8)

LittleJohn · January 15, 2016, 09:36:20 AM

I know for typical stick build houses, if you are using a 2x__ for a joist application the rule of thumb is to not exceed the 1:12 width/height rule:
2x8 - max span 8'
2x10 - max span 10'
2x12 - max span 12'

This probably does not help, but like my old man said its always easier to over build in the begining then to go back and fix it later.
..or when will you have time to fix it right in the future ;)

dad2nine · January 21, 2016, 10:10:59 PM

Maybe the AWC span calculator might help.

http://www.awc.org/codes-standards/calculators-software/spancalc

sandsawmill14 · January 22, 2016, 07:26:10 AM

we went 12' with single full 2x10s on 16" center on my brothers barn for the barn loft but it only holds about 400 bales of hay though. its been in use for 10 yrs now and no sag or any other problems

the beams you described will just about be unlimited on weight on 10' centers

LeeB · January 23, 2016, 01:13:42 AM

Well, plans have changed a bit. the crew where doing sub par and sloppy work so I fired them. Had to do all of this over the internet because I'm not home but the pictures Lindy sent me and what she told me about is was enough. It also seems I should have consuted with her some more on this because my plans were not what she had in mind. : So, back to the drawing board and will be doing the work myself when i get home.

Peter Drouin · January 27, 2016, 06:20:11 AM

Too bad the guys did not work out.

Weekend_Sawyer · January 27, 2016, 06:35:47 AM

Glad you were able to nip it before it went too far.

Jon

sandsawmill14 · January 27, 2016, 08:05:22 AM

we got into the same problem wit some block layers when i was a kid dad got home and saw their work and told them he didnt have the money to do it twice so he sent them home (after he paid them) then me and my brother had to tear down the walls and clean the blocks before before the mortar set up :

seemed like a lot of work for a 10 and 12 year old but it was only 150 or so blocks :D

petefrom bearswamp · January 27, 2016, 08:53:42 AM

OSB is in use in hundreds of thousands maybe millions of houses and other buildings in the us I dont know about other countries.
My understanding is that the strength is at least equal to plywood.
no good exposed however.
The usual stuff at the lumber yard is 7/16" not 1/2.
full 1/2 is available,
the headers in my mill shed are 10" 7/16 osb I beams 12' ctr been there 16 yrs now no probs.
will out last me.
Snow load in my area of ny is plenty as I am in a micro snow belt area.
Very little snow there this yr tho.