How much weight can a 2x4 support?

[sleepydoc]

A regular post/question I've seen is how much weigh a given frame can support. Well, I was at a hot tub store today and back in their warehouse they had hot tubs stacked up. It might be hard to see in the pic, but the framing for these tubs was made with 2x3s. They had them stacked 5 high in places and these tubs weigh about 1000 pounds a piece meaning the 2x3s on the bottom were supporting on the order of 4000 pounds.

So given proper construction techniques, 4x4s are definitely not necessary. Even 2x4s are not necessary for our purposes.

 

[Jboone82590]

Those don't really look like they are supporting much. You could stack 3 tanks on each other with those between it and be fine. It's the tubs that are taking the weight. (Seems to me anyway)
But I have built stands out of 1x4s and one of them is a few years old.

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[abrooks12376]

Are you referring to the pallets?? If so they're made out of hard wood. And fastened with ring nails. Basically like screws when applied to hard wood.

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[sleepydoc]

No - I'm referring to the 2x3 framing of the hot tubs. If you look at the top tub that is has the skin taken off of it you can see that the entire frame is made of 2x3s. The pallets are distributing the weight, but all of the weight is borne by the framing.

 

[mjstech]

The Sagulator!!!
http://www.woodbin.com/calcs/sagulator/

Read notes and YMMV.

 

[der_wille_zur_macht]

It's a very good point. A single 2x4 post, 2 or 3 feet tall, braced at both ends, is going to be able to support at least several thousand pounds. A 4x4 is more like tens of thousands of pounds.

Stands don't fail because of inadequate lumber size in the posts. They fail because of bad design, bad joinery, or bad selection of the individual boards. Or maybe once in a while because of beams with spans that are too long.

The only real advantage a 2x4 or 4x4 has is that it's nice and chunky and easy to work with in terms of achieving good joinery if you're not a woodworking expert. And in some cases people may prefer the look of a chunky stand.

 

[Windy2]

The crush strength for different types of wood vary, but most are at about 5000 lb/in*2.
So a 2 x 4 which is really 1.5 X3.5 in is about 5.25 sq in and will crush at about 25,000 lbs if properly braced. A 4 x 4 has about 12 sq in and would hold up to 60,000 lbs. A 1 x1 would hold 5000 lbs.
If you consider ply wood then lets say the stand is 5' long and you skin it in 1/2 plywood. The plywood will have an area (14' X.5 in) or about 85 sq in of area and would hold up to 425,000 lbs if well supported.
Are we overbuilding or under-designing?

 

[sleepydoc]

Are we overbuilding or under-designing?

Well, probably both!

 

[davocean]

Keep in mind the tubs are fiberglass and flex just fine w/ out cracking, so not quite an equal comparison, not that I'm doubting the strength of 2x3 especially verticals, a horizontal span can sag over time, the greater the span the more it will sag, so notice the doubled up vertical 2x's about every 2 feet.

 

[Dr. Reef]

i know this is an old thread. But i am upgrading from 96x24x24 to 96x36x24.
My question is can a stand made out of 2x4's and 3/4" plywood on top with double legs every 2 ft can handle the weight of the final tank.
tank itself will weigh about 800 lbs and filled it should be about 3800-4000 lbs.

For reference i attached a pic of my current stand made of 2x4's only difference will be the depth going from 24 inch to 36 inch.

 

[mcgyvr]

i know this is an old thread. But i am upgrading from 96x24x24 to 96x36x24.
My question is can a stand made out of 2x4's and 3/4" plywood on top with double legs every 2 ft can handle the weight of the final tank.
tank itself will weigh about 800 lbs and filled it should be about 3800-4000 lbs.

For reference i attached a pic of my current stand made of 2x4's only difference will be the depth going from 24 inch to 36 inch.

Yes that stand will have no problems supporting your new tank..
Not a concern at all about it..

 

[Dr. Reef]

Cool thanks. I really did not wanna use 2x6 or 2x8 I rather stick to 2x4 and make more supporting double 2x4 legs etc and use 3/4" plywood.