I was approached by a neighbor today about building a 30″ high stand for her custom-made aquarium. The aquarium (not yet ordereed) will be 2′ high by 2′ deep and 8′ wide. I dug out an old physics textbook and figured out the weight of the water itself would be around 2000 lbs! (correct me if I have miscalculated). All of a sudden, this has turned into an engineering problem. Is wood or wood products an appropriate material for something that has to support over a ton? There is to be some storage space inside the stand. She wants the finish to be black, so I have flexibility in terms of materials (sheet goods, dimensional lumber, etc.), assuming they can handle the load. I would appreciate any insight.
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Replies
Hello RICKY
I dont think you should have any problems, If enginers can build bridges to suport a train thats weight could excede hundreds of tons out of wood,I dont belive you will have any problems with your aquarium.
reinforce and beef it up a little. use a good hardwood,with some old stile lap joints and mortice and tendon construction.
perhaps archs for the door openings and heavy duty 4x4 couner supports,think of building a support to hold a train up and then your aquarium will be no problem. ;)
Good luck
C.A.G.
I agree with curtis about the stand. It shouldn't be at all difficult to design a stand that is both sturdy and attractive. I dug out my copy of Bruce Hoadley's book Understanding Wood and turned to the strength of wood chapter. A 1" square leg of any of the 50 woods on the list would support 2000 pounds with strength to spare, if properly braced against buckling.
The floor may require some engineering input though. Most residential floors are designed for a maximum deflection of joist length divided by 360 with a uniform live load of about 40 pounds per square foot. 2000 pounds on a 2' x 8' footprint is 128 PSF, and is more like a point load than a uniform load. On a floor built to the 40PSF L/360 standard, you could see some pretty serious sag.
Ricky, I saw your post and since I just finished building a stand, thought I would put in my 2 cents worth. I would follow a system of supports the length of the aquarium. One of this size obviously is not going to be moveable. You say 7-8' long? Whew! What a nightmare if there was a leak. I believe I would approach it as a row of cabinets if you will, with one piece for the top(this would be key). One could go with sundry materials for the top. If I had the money, I would look into a custom piece of stone, Has the aquarium already been purchased? Is it Saltwater?(not that that matters) A series of aquariums is possble. I believe wood can do the job, provided adequate design considerations are taken into account. Steel dressed with wooden face frames would make it a little more streamlined. The manufacturer of the aquarium would have suggestions and obviously a concurrent stand for this size piece.
Ricky, I made a beatiful stand for my own saltwater aquarium very similar in size what you are looking at. You are correct on the weight. In addition, the aquarium itself will be at least 200 pounds if its made of glass. Saltwater tanks generally have several hundred pounds of crushed coral and rock in them too so you're looking at alot of weight. The bottom line is that the cabinet must be strong and solidly built but if you go to any aquarium shop and look at the the commercially built stand/cabinets you'll be impressed at how lightweight the construction is.
Mine was 7 feet long and the same 2' wide by 30" tall. I used cypress 4x4's for the four corners. I rabbeted out a notch for a 2x4 frame around the top and bottom then covered the whole thing in 1/2 cabinet grade plywood with four doors on the front for access to the cabinet below. No big deal at all. Its very important that top be supported well enough that it doesn't flex under the load. Any twisting could be disastrous ( in the form of leaks at the seams or even cracks in the glass). It must be leveled once its in the building and before any water goes into the aquarium. As stated in the other posts, the building must be capable of supporting this load.
Don't be afraid of this project. Its not that big a deal and with a little research you should be able to knock it out. I bet if this woman knows anything about aquariums and she should if she's getting into one this big she's got a personal library full of great reference books. If not, go to the library, check out some books on aquariums and you'll find design ideas.
Mine had a matching seperate removable top that housed the 4 8' VHO flourescent lights too. Complete with fans to remove the heat generated by those monsters.
Good luck, I'll be curious to see how it goes. If I can answer any questions let me know.
Hugh
I've built a couple of aquarium stands, that has been a few years and they are still in use. The key to the design I used the wood in compression not bending. These stands were about 4' long, 2' deep and stood about 30" tall. Roughly half the length of yours. I made two open ended plywood boxes roughly 20" square. The open ends being the top and bottom. Add a top and bottom that span these and you have a stand. Make one of the sides of the boxes a framed in door, and you have storage.
Hopefully you understand the basic idea. By adjusting the number of boxes and their size, you can make a stand of any size you want.
For what it's worth, I agree that the more difficult issue may be the floor. The good thing is that the acquarium will probably be against a wall, and the wall may have support right below it. But if you're looking at something that could weigh up to 2,500 or 3,000 pounds, I'd think about asking an engineer. As posted above, I don't think your typical residential building is built to hold that kind of load.
Wow, this question hits home. I used to be big in aquariums, had about 6 of them running at one time with two of them being 135g and one a 100g. A lot of guys have already pointed you in the right direction, but I have to chime in as well. So here it goes:
1. Wood is very good in compression. Design the aquarium based on the aesthetics, the wood will do the rest- a tank that big may require a heavy looking stand or it may look to scary. A key thing is to distribute the weight so you don't have those point loads. It may be o.k. for a slab on grade but on a wood floor something will give. Possibly having supports at 24" o.c. with cabinet doors in between supports.
2. Between the bottom of the tank and the top of the wood, place a 1" closed cell styrofoam pad, (blue board). If the floor is uneven, it will cause unwanted pressures on the tank, that is bad. The styrofoam will absorb some of these uneven pressures and distribute them accross the tank's bottom - note that only the perimeter of the tank will be supporting the tank's weight. I have seen my kids jump up and down on the wood floors in front of the 135g tank - who knows what kind of stress that caused on the tanks corners!!
3. Use 1/4" or thicker plywood or solid wood between supports at the back and sides to prevent twisting or racking of the stand.
4. Location of the tank over a beam or bearing wall is ideal. Anywhere else and some additional reinforcement may be required on the floors - assuming we have wood floors. It would be ideal also if the stand is secured to the wall, particularly in seismic areas - hate to see something this big topple over.
5. The finish has to resist lots of spills, especially when big fish try to make a break for it. Marine varnish maybe - it could be overkill, polyurethane may be enough, three coats minimum. Glue: Titebond or polyurethane.
Well, those are just some of the items to think about, nothing scarry but it needs some thought. Good luck with it.
Marcello
Thanks everybody for your prompt responses. This is the first time I have posted a question regarding a project problem and you guys have really come through. Special thanks to those that mention floor support concern. Fortunately, I am in Southern California, so if her house is anything like mine (we're in the same subdivision), then the house is built on slab. I hope she has the good sense to locate the tank on the ground floor.
I like Ed's idea of a torsion box construction; the dimensional lumber I find around here is usually a little too wet to work. After my last big project pushed the capabilities of my small shop to its limit, I swore off doing anything nearly this size again and anything remotely resembling an installation. But here I am a year later, and I could use the money. Oh well, once I run the numbers I'll bid it on the high side so that it'd be worth my while if she wants to go ahead. At least my delivery cost will be low. I'll keep you guys posted.
I've tried to make myself stay out of this -but. Worry about the joinery and the stretchers. I actually did use to design timber bridges and it isn't the compression in the legs that you need to worry about it's the shear i.e. stress on joints.
I'll shut up,
Jim P.E.
Jim,
I'm not so sure that the people who are asking about this aren't looking for the advice of ones who know. Perhaps you could step out and share your expertise with all us wanna be engineers so we'll be more informed. I would like to hear what you've got to say about this thing. What about that shear stress?
jdg
Jim: Don't need to shut yourself up, by all means speak up. You are right about the shear on the joints - if anywhere, that is the place most likely to fail. Possibly double tenons with pegs going through them would be enough, (maybe even with the 45 deg tongue on top of each one like in the latest issue of FWW). Or maybe bridle type joints. I am an architect so I probably know enough to be dangerous, hehehe. Lets try to stay away from gusset plates though, hehe. I know something can be done with the joinery to emphasize it as part of the design. How about the span between supports? It would depend on the size of the "beam", that would also affect the shear on the joints.
Ricky: It would be interested to see your design, once you get the commission, and see structurally how it all fits together.
Marcello
Guys,
I'm not trying to not give you what I know, I just don't know how to make an answer that is thourough enough not to get you into trouble and short enough not to bore you to death.
I'll try to just give you short course. Air dry white oak for example has a compressive strength (parallel to grain) of about 7400 psi, so theoretically a one inch square leg would more than support the tank (might be kind of tough to balance it). The same wood has a shear strength (perpendicular to grain) of about 1300 psi. You start to see the problem. Then to make the matter worse and more difficult to explain horizontal shear which is the way most wood structures fail (split along the grain) is maybe half the shear strength perpendicular to grain. Horizontal shear is what controls design in most wood structures.
A formula for horizontal shear (HS) on a rectangular beam is HS=3V/2bd. With V= Vertical Shear, b=width of beam, d=depth of beam. If you keep HS less than 500 psi for most hardwoods you are probably ok. (If you nervous keep it less than 1/2 that - that what us engineers do - safety factors).
I'm sorry, I told you it would be boring. Any of you are free to email me if you really want more punishment.
Jim
P.E.
Jim, I don't think is boring, then again I read technical books in my spare time in lieu of fiction novels, lol. I know what you are saying: without a design in front it is difficult to talk about a connection - we may just be spinning our wheels. But what you posted just now is perfect for rules of thumb approach to the design. Once it is designed, the actual calculations could follow to make sure it works.
Thanks for the input.Marcello
Marcello,
Thank you for your kind words. I don't do much actually engineering anymore, do construction management and hire the engineers (something about getting old)!
Going back to being just plain old Jim a newbie woodworker that looks to you experts for my instruction.
Jim
Jim, I have worked with experts, I know some experts, but I, sir, am no expert! haha. I do like to have some fun with my band saw though.
Hiring engineers? Well, like they say, the less keys you have the more important you are. The goal is to have one master key for every lock. Seems like you are getting close to that, I, on the other hand, have gotten rid of several, but have just as many left.
Marcello
Marcello,
At my age sometimes the only key that is important is the one to the restroom :-)
Have a good one,
Jim
Jim, don't loose that key or you may end up wearing a catheter. :-)
>> the less keys you have the more important you are.
I've never heard that one. I like it.
I wonder if my high school custodians ever heard it. Or the coaches? I have this mental image of those guys flaunting all their keys... as if it gave them some status - importance.
jdg
The principal in the school is the one with the single key - the janitor is his "master key".
Marcello
Ricky,
Surprised that this wasn't mentioned by now, so I'll chip in quickly then turn the computer off, clean up after the kids (now 10:25pm) and then go to bed.
(1) As indicated, make sure that the floor is designed to handle the load, especially if it's going into an apartment or onto a suspended floor. Be a real pain if it went throught the floor. I know locally that living areas are designed at 2Mpa and libraries at 5MPa floor load. No idea what US building codes are.
(2) If you haven't built a plywood box and instead build a frame out of solid timber, the problem that you have is twofold; the stretcher rails bend under the forces, which then levers the joint apart between the stretcher and the leg, and also that joint is placed under shear (your original worry).
The most common solution here is to dovetail the stretcher into the leg, so that the legs bend inwards when the stretcher rail sags. Also prevents shear failure.
Your best bet is to look into how Billiard tables are made. All of the same problems.
Cheers,
eddie
I have built a stand for my 90 gal aquarium that is actually heavier than the aquarium itself. I built an inner frame out of 2x4's then covered the back and sides with 1/2 in. oak plywood. I covered the top with 1/2 inch exterior plywood. Then I made a face frame out of oak and put two doors and three drawers in it. I also made a matching light cover for it.
One thing that I added was electrical outlets to the back. I used a GFI as the first outlet and then added other outlets on the protected side. I also put in a switch box for a couple of the outlets. That way I can turn off the lights or the filter from a switch on the side of the stand. I only have one cord going to the wall and all the outlets used by the aquarium are protected. (You can never have enough outlets around an aquarium.)
Overkill? Maybe, but it has survived three moves and not had an accident.
Jay
(Now I am afraid to go home for fear of a major accident.)
Ricky, I'm wondering how things turned out. Did you do any more on the project? It's not that difficult, I hope you get the job. Good luck
I submitted my bid last week. She didn't seem overly eager and said she had to think about it. I wouldn't be surprised if I don't hear from her again. I think I offered a fair price, but it seemed obvious that she was expecting something "quick and easy" and priced accordingly. It's probably for the best, since I have reservations about doing any kind of large installations since my last experience. Nonetheless, thanks again for everybody's helpful advice for making a daunting project into something that is definitely achievable.
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