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I am interested as well. I keep coming back to this idea but also I wonder if I am just getting stuck on some idea I think is "cool" without it having any real merit.
It seems that if you have to build a strong foundation for the tank and another for the house, you might as well just build one extra strong foundation and put the house n top of the tank. That was my original thought, to have one big tank below supporting at least part of the house if the tank isn't large enough to cover the whole footprint of the house. I have also thought of having four large silo-like tanks at the four corners of the house. I like that idea but I can see that the engineering for seisic loads could get really complicated. A tank full of water is really heavy.
Anyway I am curious about any and all variations on the theme.
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Mark
Early on, we had similar interest for the benefits John listed. We had designed our house before knowing we'd be on catchment. After learning we would be on catchment, I determined that an area between the main house and the garage would be ideal as a 15K water storage with little to no impact on the house itself. Well, that was before I got the lowdown from the local "tank builder". What I saw as rather simple walls and floor under an already planned slab was gonna cost me between 30 and 40K based on the builder's experience with a smaller, but similarly shaped project he'd done. Oh, and that didn't include the engineering and permits. As my catchment budget was only a fraction of that, end of idea.
David
Ninole Resident
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David
I'm surprised that your tank builder got cold feet. My engineer, a rather cautious guy, has no problem using our tanks for foundations. He has stamped plans for us on several occasions for structures built on our standard round cover as well as on octagonal and rectangular concrete covers. I have one image of a small structure under construction on top of a 6000 gallon ferrocement tank here
http://pacificgunite.com/covers.htm .
Working with the round shaped cover as a foundation is ideal and won't cost any extra. Those cantilevered covers will run more however.
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Does anyone know what the code says about what you can build on top of a catchment tank? I know the plumbing code says that sewage and water piping in a ditch have to be separated by so much horizontal and vertical distance so it makes sense that you should not build the toilet on top of the catchment tank. Clearly you can have bedrooms and lanais on top of catchment tanks, since Peter and John the Architect have both done so. Somewhere it must say exactly what is permitted. What I am thinking is having a large tank under the center of the house but with toilet and kitchen plumbing around the perimeter so it is not over the tank. Is a floor level change required such that the potentially floodable floors are lower than the top of the tank? This is where the exact wording of the code comes in.
I have also considered having a couple of long slender tanks on either side of the house, outside the footprint of the living areas proper but forming the lanais. Perhaps I am getting hung up on symmetry but I also want to take advantage of what I assume will be the very strong construction of the concrete tank and make it do double duty as a very strong foundation for the house. Granted this is usually for large buildings but there is something called a cellular raft foundation with top and bottom slabs and vertical walls between forming a sort of rigid egg crate. So in effect the slab is several feet thick but "hollow" and partitioned into several rectangular or cubical volumes. Sounds like ready made cisterns to me. The same effect is what gives corrugated cardboard its rigidity compared to single layers of paper. Since the walls separating the individual compartments are shear walls and are there for strength, openings between compartments must be small and well reinforced. This would not work for an underground parking garage where you can only tolerate isolated columns here and there but seems perfectly suited for using some of these spaces as watertight tanks. Back to the code. What parts can be tanks and what must remain crawlspaces, or utility rooms depending on how tall this whole affair is? Logic would say lanais, bedrooms, living rooms, and dining rooms could be built on top of tanks while anything with waste piping could not.
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Has anyone used a shipping container for water storage? I am sure it would require some sort of liner. But I can see some advantages...the shape would be conducive to put under a deck..it would sure be strong and you would be recycling instead of buying new. I know they are being used for swimming pools.
http://theepic.wordpress.com/2008/07/28/...container/
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My gut reaction is to point out that shipping containers are actually highly engineered creations that are strong when loaded on their floor and lifted at the corners but not necessarily in other directions or ways. However, this seems to be working.
The devil's advocate in me still says that a round corrugated steel tank and liner wold be more economical. I payed over $3,000 for a 9' tall 40' long container. That's just over 19,000 gallons of storage. A similar round tank with liner ready to assemble wouldn't cost any more and would require no trial and effort to make it work. Also my shipping container is labeled that it has a maximum weight of around 80,000 lbs. 20,000 gallons of water weighs 160,000 lbs so you would have to make sure that you provided extra support in the middle especially if you cut the roof off as was done to make this swimming pool.
I don't think you would come out ahead in terms of cost. I think in the case of the swimming pool it is the long skinny nature of the container fitting in the long skinny space that makes it all worthwhile.
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quote:
Originally posted by MarkP
Does anyone know what the code says about what you can build on top of a catchment tank?...
There is a house in Leilani that the great room (LR,DR, and kitchen) sit on top of the 35K gal tank. It is set up as 3 chambers. The bedrooms and baths are outside the catchment tank footprint. It was finaled in 2007? maybe.
One of our PW's has a 14K tank as his lanai. Bathrooms sits adjacent to it but not on it.
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If I'm not mistaken, assuming this is a legal house, possibly with a mortgage, insurance and banks don't like it if your tank doesn't hold enough water to put out a fire.
Robin
Robin
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When the neighbor's house burned, the fire department was not interested in any of the close by tanks because they did not have hydrant style hookups. They had no interest in "sucking" the water out of the close by tanks. Since so many houses have 4k to 7.5k catchment tanks, I think the 10k gallon insurance "requirement" is bogus.
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quote:
Originally posted by mdd7000
When the neighbor's house burned, the fire department was not interested in any of the close by tanks because they did not have hydrant style hookups. They had no interest in "sucking" the water out of the close by tanks. Since so many houses have 4k to 7.5k catchment tanks, I think the 10k gallon insurance "requirement" is bogus.
Thats what the firemen told us. They dont even use that. Rather the best thing is to be within 3 miles of a hydrant.
Daniel R Diamond
Daniel R Diamond
