How much weight can a doubled up 2x4 hold?

[Jeff000]

Everyone on here over builds stands like crazy.
I built my 90g stand from only plywood and I am sure it would hold many times the weight of the tank.
Building my 32x32x72 stand from 2x4.
Basically building like 5 stub walls for it to sit on, with the 4 corners being doubled up 2x4.

I am quite positive what I am building is overkill, but would like to know how much a 2x4 and doubled up 2x4 could actually hold.

 

[ELGUAP0]

You would have to hope we have a stuctural engineer on the site to really answer this. Simply because in applications like aquariums it isn't really the load bearing abilites we are concerned with. It is the fatigue endurance we are concerned with. Basically, how long can it hold up to the stress over time. Which is why "everyone over builds like crazy". Calculating this is way beyond what my brain can process.

 

[gbru316]

It's not compressive loads that you need to be worried about, it's lateral loads. A single 2x4 in each corner would adequately support the tank provided it never encountered lateral loads.

The purpose of the stand is to keep the 4 corner posts in a vertical position. Build it for this purpose and you shouldn't have any problems.

Check out this thread

 

[package]

The doubled up 2x4s in the corners of the stand would hold up the front of your car. If you have concern about the 2x4s in the corner on a 90g, you would lose your mind if you saw a stock Perfecto 265g stand = scary.

 

[gbru316]

The doubled up 2x4s in the corners of the stand would hold up the front of your car. If you have concern about the 2x4s in the corner on a 90g, you would lose your mind if you saw a stock Perfecto 265g stand = scary.

Plywood is stronger than 2x4's

 

[Jeff000]

It's not compressive loads that you need to be worried about, it's lateral loads. A single 2x4 in each corner would adequately support the tank provided it never encountered lateral loads.

The purpose of the stand is to keep the 4 corner posts in a vertical position. Build it for this purpose and you shouldn't have any problems.

Check out this thread

Ok makes sense, so a sheet of 1/2" plywood on the ends and one lengthwise will keep everything nice and square and holding the weight even in the event of a large lateral load.

The doubled up 2x4s in the corners of the stand would hold up the front of your car.

The tank weighs more than the front end of my car....

 

[gbru316]

Ok makes sense, so a sheet of 1/2" plywood on the ends and one lengthwise will keep everything nice and square and holding the weight even in the event of a large lateral load.

maybe? I don't think this would take care of any twisting loads either. I'm not a structural or mechanical engineer, so this is merely my opinion.

I do what many others do when building stands; overbuild to make up for underengineering, because I don't have the background to adequately analyze the situation.

 

[ruiny]

The strength of the wood is rarly a concern in most stands.
It is the lateral strength that is the concern.

The bigest error I see most often in home build stands is that the fasteners are load bearing.
The weight of the tank need to be transfered trough the stand to the floor.
Screws, glue, nails, whatever should not be load bearing in any way.
They stabalize and hold the stand togther, not support any weight.

 

[RocketEngineer]

Something I posted back in 2007

Ok folks, I ran a couple numbers. One 2X4 on end, 24 inches long, will support 19000+ pounds before it deflects sideways enough to fail.

As far as I know, the numbers haven't changed since then.

If you want to build the entire stand from 2X4s, you need a center leg on the 72" sides or you will have deflection issues supporting the tank.

RocketEngineer

 

[Jeff000]

Something I posted back in 2007



As far as I know, the numbers haven't changed since then.

RocketEngineer

Sweet.

I'll forgo the double up and just cross brace to prevent any lateral movement. And make sure fasteners are not holding the load.

 

[jerpa]

If you have concern about the 2x4s in the corner on a 90g, you would lose your mind if you saw a stock Perfecto 265g stand = scary.

Agreed. My marineland stand for my 120 consists of plywood sides and bottom, 1x3 corner supports, no center brace, and a back that consists of an 8" wide piece of plywood and is otherwise open. It gives you an idea just how overbuilt our stands are. Cheap, easy, and strong is good though

 

[uncleof6]

As far as load bearing capacity, 2 x 4 lumber is not needed for this small load either. 3/4" hardwood plywood, is still overkill for this tank. Plywood don't rack under lateral load either....there isn't anywhere for it to go, it is already on the floor.

 

[Jeff000]

As far as load bearing capacity, 2 x 4 lumber is not needed for this small load either. 3/4" hardwood plywood, is still overkill for this tank. Plywood don't rack under lateral load either....there isn't anywhere for it to go, it is already on the floor.

I'm not sure what you mean by it is already on the floor?

But I built the stand from 2x4, 5 stub walls of three 2x4 with the corners having a two 2x4 making a 90.

plywood on top for a smooth surface for the tank, and to tie everything in.

Here it is before the plywood topper.
The side farther from the camera will have step mounted to the stand, so will have a horizontal 2x4 about half way up.
The verticals are 36".
The side closest to the camera will have double 5/8 drywall (so there is a small lip at the glass)



Any recommendations?

 

[funkyfish77]

WOW . Skin that sucker and it will hold a car . I thought I over built stuff . Nice build so far man .
Good luck

Funky

 

[funkyfish77]

Sorry double post.

 

[DavidinGA]

Wow talk about overkill!

Sent by Razr Maxx

 

[Jeff000]

Lol, overkill? And here I thought I was being reasonable.

 

[Luckless]

Don't worry, you are being perfectly reasonable with excessive overkill. Nothing wrong with a little excessive over kill for some things for that extra piece of mind.

Now, when the 'stand' starts to resemble something more akin to a solid butcher's block, then you're going overboard a tad.

Personally I would rely on a plywood skin, back and sides, to keep stuff inline and from wanting to slant to either side. And maybe a full panel on the middle support to keep it from racking. Full sized plywood sheets properly glued to the sides with a moisture resistant adhesive will give you many times the strength of the cross members you have now.

Reasonable sized holes can be cut in the panels for pies and access. (Keeping corners rounded for larger cut outs helps with more even stress.) And you may even want to skin the front and cut openings to the voids between the uprights, with rounded corners, for added insurance against things tipping. You don't look like someone who wants to leave things at merely "More than good enough" in the strength department.

Random mention for any future projects that you're looking to go over strength on, boards have more strength in their longer dimension, so laying the 2x4s flat across those spans, rather than up right on the narrow edge, means that they have a fraction of their potential strength.

Are you putting any kind of sump, or multi-tank sump below that? I wonder what would be the most reliable means of getting a tank in each section such that it can be linked to the next in some fashion? Personally I think I would be tempted to go with slightly tall tanks, custom made from acrylic, and designed so they get plumbed together with pipes running across the front near the bottom. (With shut off valves so each can be isolated for whatever reason may be.)

 

[Jeff000]

Don't worry, you are being perfectly reasonable with excessive overkill. Nothing wrong with a little excessive over kill for some things for that extra piece of mind.

Now, when the 'stand' starts to resemble something more akin to a solid butcher's block, then you're going overboard a tad.

Personally I would rely on a plywood skin, back and sides, to keep stuff inline and from wanting to slant to either side. And maybe a full panel on the middle support to keep it from racking. Full sized plywood sheets properly glued to the sides with a moisture resistant adhesive will give you many times the strength of the cross members you have now.

Reasonable sized holes can be cut in the panels for pies and access. (Keeping corners rounded for larger cut outs helps with more even stress.) And you may even want to skin the front and cut openings to the voids between the uprights, with rounded corners, for added insurance against things tipping. You don't look like someone who wants to leave things at merely "More than good enough" in the strength department.

Random mention for any future projects that you're looking to go over strength on, boards have more strength in their longer dimension, so laying the 2x4s flat across those spans, rather than up right on the narrow edge, means that they have a fraction of their potential strength.

Are you putting any kind of sump, or multi-tank sump below that? I wonder what would be the most reliable means of getting a tank in each section such that it can be linked to the next in some fashion? Personally I think I would be tempted to go with slightly tall tanks, custom made from acrylic, and designed so they get plumbed together with pipes running across the front near the bottom. (With shut off valves so each can be isolated for whatever reason may be.)

I'll do some skinning here, all joints are glued.

The boards on top are to keep the verticals in place, not provide distributed weight, if I was going acrylic I might have designed it differently, but with glass I am not worried at all.

Sump is not going under the tank.
Only thing under the tank will be the pump and a couple drawers.

I'll post a couple more pictures tonight.

 

[uncleof6]

I'm not sure what you mean by it is already on the floor?

But I built the stand from 2x4, 5 stub walls of three 2x4 with the corners having a two 2x4 making a 90.

plywood on top for a smooth surface for the tank, and to tie everything in.

Here it is before the plywood topper.
The side farther from the camera will have step mounted to the stand, so will have a horizontal 2x4 about half way up.
The verticals are 36".
The side closest to the camera will have double 5/8 drywall (so there is a small lip at the glass)



Any recommendations?

It won't rack. Only way for it to rack, is one end go up the other down. The other end is already down........to get it to go over you have to pick the other end up. Understand now?

Stand you built here looks good, but it is excessive overkill, but there really isn't anything reasonable about excessive overkill, it is simply excessive. The Plywood box is overkill.

What remains, since the stand is not finished yet, is whether it will come up flat, plumb, level--after the dimensions change with temperature and humidity, causing the thing to display a short end, twist, or other anomaly, which is the subject of too many DYI stand threads.