Largest possible tank

[HooKooDooKu]

Originally Posted by JasonC

Excellent information HooKooDooKu. Did your calculations, though, include necessary safety factors, or were you working off of pure breaking strength of the materials listed?

Also, others, if you are going to look into modifying your home for tanks, make sure to verify #'s given with your *local* building codes. What is allowed/required will vary widely just from one side of the country to the other... not to mention for codes in other countries.

For a large tank, my big suggestion would be to make sure that you have cross braced joists in the floor the tank is sitting on. Not only will this remove any springiness from the floor, it will prevent permanent warpage of joists the tank is sitting on over time. Of course, the only way to do this, though, is if you have an unfinished ceiling on the level below, or you are willing to rip out a lot of ceiling.

I didn't want what was already a long post to get bogged down in too many details. The actual details of the the 40 pounds per square foot are not based on breaking strength but actually a percentage of deflection in the wood. I do not recall the exact details and numbers, but it works something like this: If a floor is spanning a distance of 10 feet, the floor joists must be sized and spaced such that a 40 pounds per square foot load applied to the entire floor will not cause the center of the floor to deflect by more than 1/4". Again, I don't recall exact numbers, but that distance of 1/4" is actually some mathmatical formula based on the length of the span, and the desired pounds per square foot load.

The discussion of the wall strength is based on the notion of the upper end of typical floor strength designs is about 100 pounds per square foot. I do NOT know if it would take 2x4 studs on 18" centers, 2x6 studs on 18" centers, or doubled up 2x4 studs on 18" centers. I'm just calculating backwards from the notion of being able to build a floor that can hold 100 pounds per square feet in a typical sized room.

[HooKooDooKu]

Originally Posted by jsoong

HooKooDooKu, I think you have misunderstood the 40 lb/sq ft building code.

That code does not refer to a point load on the floor, rather, it refers to the entire floor itself. <And it applies only to residential wood framed houses.> Strictly speaking, you calculate the load by the span of the joist multiply by the width of the room across the joist, and assuming a static load EVENLY distributed across the entire floor. So, if your joist spans 12', and you have a 12' room, then the load for the room is 12*12*40 = 5760lb. Note that this load rating has to support any structures above the room - so your load capacity of the room is reduced if you have a load bearing wall in the span, a heavy roof, snow on the roof, etc. ...

Thanks for including the clarification. I do understand that the 40lb/sqft is a distributed load, and all my calculations were based on that. But in re-reading my post, I see that I did omit that detail in the post.

And yes, everything was based on a wood frame house...

Thanks for the extra detail.


And just to make sure things are clear... all my numbers are general estimates, some of them making educated guesses based on what little I do know about wood framed houses. I'm not a house designer, nor do I know all the details regarding building codes. But I did research the subject enough so that I could reinforce my deck and feel comfortable with my children playing in a 500 gallon "kiddie" pool on a deck 8 feet off the ground.

And so I whole hartedly agree that basically with your basic summary...
which I would summerize this way...

Anyone installing a tank larger than what you can pickup at the local PetSmart (or similar store) is going to need to look into reinforcing their floors.

[JasonC]

Originally Posted by HooKooDooKu

I'm not a house designer, nor do I know all the details regarding building codes.

Even a seasoned House designer (architect) will tell you the most math they know is the phone number to their structural engineer ;P

[HooKooDooKu]

Originally Posted by JasonC

Even a seasoned House designer (architect) will tell you the most math they know is the phone number to their structural engineer ;P

Yea, when I was studying Engineering in collage, we had at least one teacher that phrased it something like this...

"An architect determines what color the light switches are, and engineer determines how to hold the building up."

[jeeptree]

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