Need to build a free standing deck that can handle 22,000#

[Jason Shelby]

I need to build a free standing deck that is capable of handling a 2,550 gallon water tank, estimated weight 21,281#. However I cant find a chart or calculator that tells me the size of joists I need to build with. I know its a lot of weight, but due to the location of the water tank, I need to put it on a platform.

[Malcolm McLeod]

I would strongly recommend you consult with a licensed structural engineer.

[Malcolm McLeod]

I would strongly recommend you consult with a licensed structural engineer.Please!!!!

...And welcome to the Creek.

[Jason Shelby]

I was afraid that would be the answer I would get. So on to plan "B".

[Malcolm McLeod]

I was afraid that would be the answer I would get. So on to plan "B".
I'm sorry - since I'm betting that is not the answer you wanted. I can think of at least a dozen ways this could go tragically wrong, and it is not my chosen field, so there are probably a dozen more I can't think of.

[Garth Almgren]

Yeah, it might not be the answer you're looking for, but elevating 11 tons is not one of those projects where you want a bunch of people on the internet telling you something "ought to be good enough". :eek:
If I asked my cousin who builds decks professionally how he'd build it, I'm sure he'd say the same thing - ask a structural engineer.

[Todd Mason-Darnell]

Ah come on--if it is a 6ft diameter tank, he is only looking at a load of 753 lbs/sq ft (psf) --that is something we could all just guess at. :rolleyes:

Seriously, you need to consult a structural engineer. As a comparison, most decks are designed around a 50lb psf live load.

[Wade Lippman]

I haven't the faintest idea, but how big and high is it?
Presumably that would make a difference.

[Ken Combs]

In addition to sizing the lumber, one also needs to determine the area and material needed to bear the load on the ground. How many supports, depth, load bearing area each and total etc. Just another voice for an engineer.

[Pat Barry]

Need more info. How tall is this deck. How big (diameter / rectangle) is the water tank? Is this a hot tub?

[Lee Schierer]

Without specific details, any attempt to design this deck is fraught with failure. What are the dimensions of the tank, weight of the tank, height above the ground, amount of slope if any, type of soil, location in the world, weight of any additional equipment, will people be on this deck, etc.

I think the advice of hiring an engineer is spot on.

[John K Jordan]

I need to build a free standing deck that is capable of handling a 2,550 gallon water tank, estimated weight 21,281#. However I cant find a chart or calculator that tells me the size of joists I need to build with. I know its a lot of weight, but due to the location of the water tank, I need to put it on a platform.

If you need it... When building a roof with a long beam I wanted to consult a structural engineer. I found a good one at a reasonable cost by calling one of my architect friends who are constantly buying an engineer's time. I think I paid the guy about $100 for his calculations.

For that kind of weight you not only have to consider the support structure but how it is supported by the ground. I've been around a lot of industrial construction as an inspector and otherwise, and I've seen and documented exactly what goes into the ground for heavy loads. We did soil compaction and content tests (water and organic material) and had a drill rig for deeper analysis. Is it over karst? Solid rock? Underground water? Earthquake area? What is down hill? Any special permits needed? Periodic inspections?

I suspect an engineer will spec a platform built from steel with a lot of concrete in the ground. Constructing from wood might be easier and cheaper now but what about some years from now when wood starts to degrade?

I know a guy in Canada who just put in a big water tank in to accumulate spring water for residential use. I think the rules there required tanks sit solidly on a reinforced concrete pad with footers.

JKJ

[Roger Nair]

In concept I'd look at old railroad watering tanks and tanks atop old NYC apartments. However, that might not fit your need. Like everyone else, an engineer must pass on the design and the cost will be a lot higher than $100, expect a cost with another zero and a multiplier, you will need a coordinated design not a simple beam calc.

[Dan Friedrichs]

Is this a hot tub?

Uhhh, a 6 person hot tub is ~350 gallons. Maybe it's a 45-person hot tub :)

[Tony Zona]

And it must be designed with a sufficient safety factor, not just for the 22,000 pounds.

[John K Jordan]

...and the cost will be a lot higher than $100, expect a cost with another zero and a multiplier, you will need a coordinated design not a simple beam calc.

You are right about that. My $100 bill was probably the most trivial job the guy had ever done.

I wonder if tank manufacturers would have engineering guideline documents for their tanks as a starting point or sanity check for potential customers.

JKJ

[Pat Barry]

Uhhh, a 6 person hot tub is ~350 gallons. Maybe it's a 45-person hot tub :)
Sure, a 45 person hot tub. I couldn't afford to keep it hot.

[Pat Barry]

And it must be designed with a sufficient safety factor, not just for the 22,000 pounds.
Thats right, is the estimated weight including the 45 people? That could easily add another 6000 pounds to the load.

[Ole Anderson]

I put my hot tub on a deck elevated 9 feet up years ago. But then it is only 300 gallons and I am a civil engineer. I wouldn't try such a large tank without using steel posts and beams, not that it couldn't be done with wood. Which is definitely a project begging for an engineered solution as everyone has noted.

[Brian Henderson]

You are going to have to go to a structural engineer and get it signed off, plus all the permits from whatever city you are in. If you try to go around this step, it is likely that the city will come out and order you to tear it down and start over. You'll just be wasting time and money not doing it right.

[Bruce Wrenn]

Go look at a wooden railroad bridge. It will give you BASICS of deign. Surprisingly, timbers are much smaller than you would think when you realize modern locomotives weigh almost a million pounds each. Pilings are driven to refusal, meaning they can't be driven any deeper. Got a pile driver? Driven piles offer resistance to racking due to bearing sideways on soil, plus they are X braced. Hire a PE to design your structure, said by old tight wad himself.

[Bill Jobe]

Just a guess....koi pond?

[Todd Mason-Darnell]

Just a guess....koi pond?


I am betting rainwater collection.