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Old 08-13-2010, 07:40 PM   #16
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2 x 4 Strength?


Now that I see your application, I would get three 10' 2x4s. Use one 24" piece on each side if it helps you tie them together. Beyond that, whether you need a center piece going up to a ceiling joist depends on how much weight you're putting up there.

I would not go with short pieces parallel to the long walls, as in your original drawing.

(Then again, I'm a writer, not a carpenter.)

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Old 08-13-2010, 09:15 PM   #17
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2 x 4 Strength?


Quote:
Originally Posted by mopowers View Post
Assume 800,000 PSI for the modulus of elasticity [MOE] for the 2x4 as a worst case, I = 5.4 and y = 3.5/2 = 1.8".
http://www.engineeringtoolbox.com/be...on-d_1312.html
Each short 2x4 will be very strong.
I'd worry more about shearing off the four wall fasteners.

Try it. Cut a 2x4 to length, support it at each end 1/8" above the floor, stand on the center of it on one foot and see if you can see any bending at all at midspan.
You can also use this method to measure the MOE for your particular wood.

Last edited by Yoyizit; 08-13-2010 at 09:31 PM.
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Old 08-13-2010, 09:31 PM   #18
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2 x 4 Strength?


The design tables have little real value since this is a unique application and probably not under a code and the design tables do not usually cover shelving for design loads. They might be intersting from an academic standpoint.

The important thing is that is it strong, functional and stable, which could be limited by the connections and the structure it is attached to.
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Old 08-14-2010, 06:01 AM   #19
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2 x 4 Strength?


I agree with no short joist and do three the long direction.

If you’re worried about sag use 2x6. Woods cheap right now.

Don’t limit yourself to 24”, find the studs in the wall if you find one at 20-24” great otherwise go to the first stud beyond that.

You’ll end up with a stronger shelf and a little more space.
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Old 08-14-2010, 11:56 AM   #20
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2 x 4 Strength?


Concretemasonry, there is a ceiling joist table, on post #11 = 150# total load.

If the short 2x are omitted and the span is 2' ----- it's the same load. To add another 10' 2x4, at 2' span, or 12"on center, you carry the load = 15# per sq.ft. on the middle one and on the rim one = 15# together total 30#. OR 300# total load.

As Ron said, change to one 2x6 in front and 2x ledger with/without the short spacers, total load is 756# or 75# per sq.ft. for Doug fir.

Be safe, Gary
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Old 08-14-2010, 12:37 PM   #21
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2 x 4 Strength?


GBR - I do not believe in absolute use of joist tables even though I have been involved in the creation and code writing while being a structural engineer. They are basically for code purposes, which are based on a load capacity where failure would be a problem with human safety (life safety) if a building fails. I don't see this to be a ceiling joist or floor joist for code compliance. I don't see this as a code controlled situation, so the tables are just a guideline depending on the expected use. If it was a code problem, then I would recommend getting a permit and inspection, which is insane, but it would drive a plan checker and inspector insane and they would not want to get bothered.. Deflection is also not a problem.

As you correctly pointed out the elimination of the short 24" 2x4s and substituting a 10' 2x4 does double the load. This coupled with the 3/4" plywood will give a very robust storage area, especially since it is 24" deep so there is little room for a person and any appreciable space to occupy. If it was deeper, then the possibility of more load increases.

It is obvious that a 2x6 would be stronger, but the height would be decreased.

Attach the 24" long sidewall 2xs as well as possible, because this is where the real load is.

All too often, people involved in the strict use of codes in the U.S. and can get out of touch with the real world and practicality. I have a structural engineer friend in South America that has designed a number of projects with 1 to 10 - partially reinforced loadbearing masonry buildings using 6" thick block walls with no concrete or steel columns or beams that ranged from 10 to 22 stories. They have been doing this since 1972 when the first building were designed using the existing U.S. standards. When I asked him what codes and standards they used, he said "We use your codes and standards, but use them better based on experience, technological improvements, construction practices and prudent enforcement".

Dick

Last edited by concretemasonry; 08-14-2010 at 12:40 PM.
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Old 08-14-2010, 07:03 PM   #22
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2 x 4 Strength?


Thanks for all the help guys. I got started on the shelving today.

Quote:
Attach the 24" long sidewall 2xs as well as possible, because this is where the real load is.
How would you attach them? I was just planning on running (2) 3" screws on every stud it hits. Keep in mind the side ledgers won't be 24"- they'll be about 5' for more shelving down the side. I just omitted that from the sketch for simplicity sake.

Thanks again!!
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Old 08-14-2010, 07:20 PM   #23
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2 x 4 Strength?


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Originally Posted by mopowers View Post

How would you attach them? I was just planning on running (2) 3" screws on every stud it hits.
I'm curious what people have to say about this. Screws would have less tendency to pull out, but nails have a stronger shear weight rating. Lag bolts would split the difference I believe.
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Old 08-14-2010, 08:13 PM   #24
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2 x 4 Strength?


I'd certainly use lag bolts to anchor the ledgers. There is going to be both shear force and lateral (pulling) force on the fasteners.

I would use at least 5/16" x 4" lag bolts with flat washers.
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Old 08-14-2010, 08:18 PM   #25
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2 x 4 Strength?


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I'd certainly use lag bolts to anchor the ledgers. There is going to be both shear force and lateral (pulling) force on the fasteners.

I would use at least 5/16" x 4" lag bolts with flat washers.
one per stud? or 2?
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Old 08-14-2010, 08:24 PM   #26
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2 x 4 Strength?


http://www.awc.org/calculators/conne...ction+Capacity

Be safe, Gary
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Old 08-14-2010, 08:28 PM   #27
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2 x 4 Strength?


Quote:
Originally Posted by mopowers View Post
one per stud? or 2?
One per stud should be sufficient. Pre-drill the ledgers and pilot drill into the studs to prevent splitting.
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Old 08-14-2010, 08:43 PM   #28
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2 x 4 Strength?


You could also install the side 2x's lower & have the 10' 2x's sit on top of these
Then add blocking between them
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Old 08-15-2010, 10:06 AM   #29
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2 x 4 Strength?


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Originally Posted by GBR in WA View Post
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Old 08-15-2010, 12:13 PM   #30
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2 x 4 Strength?


You should see my bookmarks library.......... lol.

"You could also install the side 2x's lower & have the 10' 2x's sit on top of these
Then add blocking between them " -------- from Dave.

Using a hanger, LUS 2x4 (L= lumber, U= shape, S= shear) rather than putting 3- 10d into the 1-1/2” of meat bearing there with very possible splitting out.

The hanger has a shear resistance of 490# using 10d, below toe-nails (3-16d = 561#), but less chance of splitting.
http://www.strongtie.com/products/co...ace_ss-df1.asp

http://books.google.com/books?id=_CP...age&q=&f=false

Good for CA and FL., though no inspection required in this application. This will help hold the side walls together in a high wind or seismic area, especially tall walls that will flex at mid-height. I’d hate to find all my storage stuff on my car windshield for lack of using a shear hanger over toe-nails.

Be safe, Gary

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