water tank on platform

[mako]

I want to put a 10,000 lt water tank on a low platform, say 200-300mm off ground level. Dont want it on slab. Im figuring i will need lots of timber under it. Any idea of bearer/joist/ span for this sort of weight? Any suggestions comments welcome. Basicly it will be a mini deck but strong as buggery.

[Ivan in Oz]

I'm out in "The Bush" and saw this the other day.
Chap had used 4 Power Poles to form a SQUARE Raised area.
It was about ONE Metre larger on the 4 Sides than the TANK.
Do not know what he had used as fill, but looked like Deco Granite.

[silentC]

I can't imagine why you'd want a timber stand in that situation, it's the perfect application for a small slab.

Put it this way: 10,000l weighs 10,000kg. None of your standard span tables are going to cover that. If you want to do it properly, you'd need to get an engineer's design for it, silly as it might sound.

Having said that, National Parks who are a law unto themselves, usually just chuck them on a bunch of sleepers arranged on edge about 300mm apart with 40mm thick planks as a deck.

[TEEJAY]

Make sure your timber is treated against bugs and rot - be a good idea to put the timber on a concrete slab :)

[SilentButDeadly]

This is fairly straightforward.....basically you'll probably need five perhaps six steel tapered flange beams, lots of bricks or some zinc coated steel (for the piers - about 20 to 25 of them) and quite a few lengths of 200x50mm treated pine OR a few sheets of corrugated iron....

The thing is this is a bloody fiddly exercise. Heaps of piers for starters then there's the beams - the minimum length for new steel is 9m and they cost a bomb so 2nd hand is your best option.

The corrugated iron is the easiest part....! And before anyone says otherwise....it works. And it works beause the ten tonnes is distributed over nearly 5.5 square metres assuming a 2.6m diameter.....which is less than 2kg per square metre. And there's a tank stand out there that has stood for over ten years built just that way...

Personally...I like Ivan's option......build a 300mm high box, fill it with dirty metal and top with sandy loam or crusher dust and throw your tank on top. Simple and straightforward....

[DvdHntr]

If it is to be 200-300 off the ground then just put a series of 200-300 deep sleepers under it. Just make sure you have enough so that it doesn't crack the tank or make the ground sink locally.

[Vernonv]

And it works beause the ten tonnes is distributed over nearly 5.5 square metres assuming a 2.6m diameter.....which is less than 2kg per square metre. And there's a tank stand out there that has stood for over ten years built just that way...


I work it out at a little over 1800kg per square meter ... or have I missed something:?.

1800kg per m2 = 18kg per square decimetre, which doesn't sound too bad ...

[malb]

Have a 22.5Kl steel tank from Onesteel, their base specs allow for timber, even surface level and maximum gap anywhere not more than 3mm.

[Bloss]

Not as simple as it sounds. You have to be able to fix the tank to the structure and critically enable it to resist wind forces - when empty or partially so (as when full the inertia of the 10K litres/ kgs is sufficient).

That's why slabs are mostly used for tank bases at that height and often with a slightly deeper footing around the outside (as used for houses) - in this case to resist tilting.

If you use timber then the posts have to be in holes of sufficient depth to resist those lateral forces.

Of course commonly the tank is poorly attached to the base (or not at all) so is uplifted and blown over in string winds (not just cyclones) so you need to make sure the tank is well secured to the stand as well as ensuring teh stand itself is strong and rigid enough.

But what you suggest can be done - posts to a minimum of 500mm and better if 800mm or 900mm witha hole diameter of no less than 300 mm. Treated timber or gal steel (you could use stirrups, but they would need to have good long legs and you would need to have them almost flush with top of the concrete).

There are ready made steel stands available and these can be bolted to existing or new slabs. If the tank is protected by a dwelling wall then the wind forces are less an issue. Tank shape and position relative to the wind direction is also a consideration.

There is plenty of info about stands and installation generally on tank makers' sites to eg:

http://www.bushmantanks.com/Installation/Preparing%20for%20Your%20Tank.aspx

[SilentButDeadly]

I work it out at a little over 1800kg per square meter ... or have I missed something:?.

1800kg per m2 = 18kg per square decimetre, which doesn't sound too bad ...

You've missed nothing......but I have......'centi' :2tsup: