4300 Gallon Plywood Build (3600+ Take 2)
- Thread starter Nolapete
- Start date
I guess I'm not so much worried about the cement slab or even the wood that sits on the joists on the bottom of the tank. It's the 20"+ squares on the bottom of the tank that only have 3/4" of plywood standing between 4300 gallons of water and a major leak. If those squares are 24", that's a full ton of weight sitting on 3/4" of plywood and nothing underneath of it. that WILL collapse. I want nothing less than your complete success with this project. No carpenter worth their salt would take that chance though.
Built a budget ice freezer for storing 500# blocks of carving ice using staggered seam layers of 3/4" BC SYP plywood over 11/16" T&G OSB glued and screwed 6" O.C. spanning 10 1/2" clear span squares (12" O.C. sleepers w/ 12" O.C. cross bridging). Freezer was in daily use for 7 years with only a new coat of flint seeded epoxy after the 4th year. The ice was palletized and stacked 3 pallets high wall to wall. That was roughly the equivalent of 12' of frozen water plus the weight of the pallets. The dynamic point loads were even more severe since the pallets were placed and picked with an electric reach truck that with batteries and ballast had to weigh somewhere around 1200#'s by itself, and all of that weight, plus it's load, was born by three wheels with a total contact patch of no more than about 10-12 sq. inches.
I don't recall the floor specs on this build but if it is a single 3/4" plywood base with those spans a couple more sheets of BC SYP or even OSB glued and screwed should be plenty of extra insurance for relative cheap.
I don't recall the floor specs on this build but if it is a single 3/4" plywood base with those spans a couple more sheets of BC SYP or even OSB glued and screwed should be plenty of extra insurance for relative cheap.
Also, I believe Pete said that his 4300 gallons was spread over about 100 sq. ft., so that's about 1436#'s over 4 sq. ft.
Pickin' nits but that ain't quite a ton.
If his sleepers are on 24" centers with no cross bridging I would definitely add the 2nd layer. The gluing and screwing is a critical part though so that the the whole floor acts as a single unit.
Pickin' nits but that ain't quite a ton.
If his sleepers are on 24" centers with no cross bridging I would definitely add the 2nd layer. The gluing and screwing is a critical part though so that the the whole floor acts as a single unit.
Are you a carpenter?
There's no puncture point. How is it going to collapse? It would have to move an entire sheet of plywood on most of the floor to bust through that.
There's 13,320 square inches of surface area on the bottom of the tank.
Even at 10 lbs. per gallon, that's only 3.23 lbs per sq inch.
I'm a good 250, so figuring my feet take about 100 sq. inches, that's 2.5 lbs per sq. inch. The floor doesn't even creak when I'm on it.
You're trying to tell me that .75 lbs per sq. inch difference is going to bust through the plywood? Not going to happen.
Being a carpenter is what makes the issue a little more difficult to accept. Subfloor construction using a single layer of 3/4" sheet goods is typically used to meet code requirements for 30-50#'s per sq. ft. loading not 370. The biggest limiting factor in that application however is normally the joists and beams that are carrying the subfloor, not the plywood.
In your Monster Fish Tank you're working off of an uber slab so you've got no real "foundation" issues. The weakest point in the vertical loading would be the wood deck. Since you're using sleepers that are in compression along their entire length the only suspect load is what the plywood carries along it's unsupported span across the sleepers. If you were to test your design to the point of failure the I think it would be a close race between the fasteners pulling and tearing out from the plywood deflection and the plywood failing. Your 5 1/2" wide sleepers and cross bridging provide so much meat at your attachment points that those loads would doubtless be immense.
The big difference in the tank build vs. "typical" residential home construction thinking is that you've completely eliminated deflection in the joists and beams by placing them on the slab. Load calculations for floor systems is again, usually limited by the carrying capacity of the joist and beams, not the plywood.
I believe that when you're talking about weight on the order of 10 times what most carpenters are trained to build a wood deck for, it causes a sort of automatic "danger Will Robinson" response. Building for that kind of loading with wood probably just strikes most carpenters as being as unnatural as seeing a 5' Pirarucu swimming in somebody's living room window.
I'm sure that I speak for everyone that's visited when I say that no one wants anything to go wrong. Any questions or comments that you receive are made with the best intentions of trying to "what if" any potential problems before you fill this monster with water. You've obviously spent a great deal of time noodlin' through this so sometimes you might have to be a little patient with us as we play catch up. A 5' water column wrapped in wood sitting in someone's home is a lot absorb (pun intended).
I'm sure the vast majority of AC members are living vicariously through you and scheming to find a way to pull something like this off on their own.
All the best! :thumbsup:
In your Monster Fish Tank you're working off of an uber slab so you've got no real "foundation" issues. The weakest point in the vertical loading would be the wood deck. Since you're using sleepers that are in compression along their entire length the only suspect load is what the plywood carries along it's unsupported span across the sleepers. If you were to test your design to the point of failure the I think it would be a close race between the fasteners pulling and tearing out from the plywood deflection and the plywood failing. Your 5 1/2" wide sleepers and cross bridging provide so much meat at your attachment points that those loads would doubtless be immense.
The big difference in the tank build vs. "typical" residential home construction thinking is that you've completely eliminated deflection in the joists and beams by placing them on the slab. Load calculations for floor systems is again, usually limited by the carrying capacity of the joist and beams, not the plywood.
I believe that when you're talking about weight on the order of 10 times what most carpenters are trained to build a wood deck for, it causes a sort of automatic "danger Will Robinson" response. Building for that kind of loading with wood probably just strikes most carpenters as being as unnatural as seeing a 5' Pirarucu swimming in somebody's living room window.
I'm sure that I speak for everyone that's visited when I say that no one wants anything to go wrong. Any questions or comments that you receive are made with the best intentions of trying to "what if" any potential problems before you fill this monster with water. You've obviously spent a great deal of time noodlin' through this so sometimes you might have to be a little patient with us as we play catch up. A 5' water column wrapped in wood sitting in someone's home is a lot absorb (pun intended).
I'm sure the vast majority of AC members are living vicariously through you and scheming to find a way to pull something like this off on their own.
All the best! :thumbsup:
CWO4GUNNER
USN/USCG 1974-2004 Weps
Im not that good a carpenter so I world have made only the viewing bulkhead the flat section made of reinforced wood. The rest would have been a wall of perfect half round circle sheet of 1/32 steel sheet bolted to one wall and the concrete floor with a padded plastic liner. It only would have become perfectly 1/2 round after filling LOL.
But you got me convinced you know what your doing, as I have never seen such unique construction, looks like you know what your doing to me.
But you got me convinced you know what your doing, as I have never seen such unique construction, looks like you know what your doing to me.
Thanks foolishfish for the info and the vote of confidence.
CWO4GUNNER, I actually considered doing that very thing with this, but with an aluminum wall to prevent corrosion. We had a 24' diameter 4' deep aluminum swimming pool with liner for 13 years whereas the two adjoining neighbors with steel wall pools replaced each of theirs at least twice in the same time frame.
I have a hard time believing that 5 ply plywood which is made with alternating directions of the grain on each layer is going to give before a joist that is just the grain going one direction. If I was putting a pile of ice blocks on it, sure I'd want the spacing to be different since that could pierce the plywood. The pond coat, construction adhesive, and deck screws are going to make the floor like one piece of wood. I could put another three sheets of plywood on the floor, but I don't think it's necessary. I'll ask Ken on Saturday what he thinks.
CWO4GUNNER, I actually considered doing that very thing with this, but with an aluminum wall to prevent corrosion. We had a 24' diameter 4' deep aluminum swimming pool with liner for 13 years whereas the two adjoining neighbors with steel wall pools replaced each of theirs at least twice in the same time frame.
I have a hard time believing that 5 ply plywood which is made with alternating directions of the grain on each layer is going to give before a joist that is just the grain going one direction. If I was putting a pile of ice blocks on it, sure I'd want the spacing to be different since that could pierce the plywood. The pond coat, construction adhesive, and deck screws are going to make the floor like one piece of wood. I could put another three sheets of plywood on the floor, but I don't think it's necessary. I'll ask Ken on Saturday what he thinks.
CWO4GUNNER
USN/USCG 1974-2004 Weps
yeah I built a steel 26' above ground pool once, cheap and incredibly durable. The liner and 4' filter cartridge lasted 10 years, only the pump had to be replaced about $70. The liner another $120
If I ever decided to do something like you are Id have to use that technology but would obviously go taller probubly 8 feet and much smaller 10'-12' across with a flat galvanized steel welded framed section to support the viewing screen which would simply mate up to a simple framed opening of the house from the garage or maybe from outside where it would second as a pond with free controlled lighting.
If I ever decided to do something like you are Id have to use that technology but would obviously go taller probubly 8 feet and much smaller 10'-12' across with a flat galvanized steel welded framed section to support the viewing screen which would simply mate up to a simple framed opening of the house from the garage or maybe from outside where it would second as a pond with free controlled lighting.
