at waht point is a standard foundation not enough??

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scalesandfins

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Apr 22, 2010
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right now i have a 300 gallon tank and it effected our rental house slightly by making one corner of the house sink faster. but with rain its gone back up.
my question is at what point (gallons) do you need a reinforced slab?
if at all
i plan on having a 700 gallon (96x48x36) acrylic tank built in the next year and im wondering if it is safe to put in a house with a normal foundation?
 
It actually made the foundation sink or just the slab it was sitting on?
 
scalesandfins said:
right now i have a 300 gallon tank and it effected our rental house slightly by making one corner of the house sink faster. but with rain its gone back up.
my question is at what point (gallons) do you need a reinforced slab?
if at all
I plan on having a 700 gallon (96x48x36) acrylic tank built in the next year and im wondering if it is safe to put in a house with a normal foundation?
Click to expand...
Hello; Each building has a limit due to too many factors to give a standard answer. Sounds like you have already passed the limit of the current palce with the 300 gallon. A 300 gallon can weigh somewhere between 3000 and 3600 pounds depending on how much gravel and stuff you have in it and the construction of the stand and the tank it self. A 700 gallon will likely be between 7000 pounds and 8400 pounds. I wiil copy and paste some web addresses from an old post on the subject. There is no set answer to the question. Each building will have to be lookled at to see how it is put together and the actual condition of the materials it is made of.
Hello; (OLD RECYCLEDPOST some words will run together, this happens when I copy and paste to the forum)) Here are some web addresses about floor capacity. The first address is a new one from a post by another Monster Fish forum member a while back. Here are the addresses again with the first being new to the list. Floor capacity depends on a lot of criteria, there is not a simple answer to the question.
This web address is added to the list http://www.cichlid-forum.com/articles/aquarium_weight.php It is perhaps the easiest to follow.
http://www.ehow.com/how_7485788_calculate-floor-load-capacity.html
The web address above is a site about calculating load capacities of floor joists. They use a formula for the strength of a beam: maximum load in pounds = FBd^2 / 9L.
The width of the wood joist in inches is B (1.5 inches for standard 2 by dimensional lumber.)
The depth in inches is d (7.25 in for a standard 2x8.)(9.25 in for a 2x10)
The distance (span) in feet is L (Unsupported distance)
F is something called the fiber stress when wood bends. It varies with the type of wood but graded lumber will be at least a 1,000 number, some are higher.
They use an example of 2x10 floor joists with a span of 14 feet on 16 inch centers and come up with 1,019 pd for each joist. They figure the area supported by each joist as 18.7 sq ft. They get 54.5 pd per square foot of floor area. I think this includes the weight of the flooring and anything else that is supported by the joists.
I looked at some other sites (Addresses listed below) and found a discussion of static loads and live loads. Two sites describe how to measure the deflection of flooring due to weight loads.
http://www.johnbridge.com/vbulletin/deflecto.pl

http://www.awc.org/calculators/span/calc/timbercalcstyle.asp?species=Douglas+Fir-South&size=2x8&grade=Select+Structural&member=Floor+Joists&deflectionlimit=L%2F480&spacing=16&wet=No&incised=No&liveload=80&snowload=-1&deadload=10&submit=Calculate+Maximum+Horizontal+Span
I found these sites interesting but hard to pin down for a general rule of thumb. Too many variables involved; Type of wood, condition of wood, dimensional lumber or engineered truss, age of wood and on and on.
http://www.eng-tips.com/viewthread.cfm?qid=62845&page=10
 
^ Very good advice, skjl47

It depends on so many things, you'll most likely need to contact a structural engineer to evaluate your situation and then reinforce the floors of which the tank lies on (unless, of course, you have the tank resting on concrete).
 
scalesandfins said:
right now i have a 300 gallon tank and it effected our rental house slightly by making one corner of the house sink faster. but with rain its gone back up.
my question is at what point (gallons) do you need a reinforced slab?
if at all
i plan on having a 700 gallon (96x48x36) acrylic tank built in the next year and im wondering if it is safe to put in a house with a normal foundation?
Click to expand...

Hello; Been thinking about this statement and cannot come up with any way that rain can "fix" a house that is sinking at one corner. At best whaterver seems to be happening during rain will likely be short term. Perhaps some swelling of the soil as it rehydrates. Are you in one of the major drought areas like texas?? As the soil dries out it does move and shift. Foundations are known to crack. Water and sewer lines break.
If you have renters insurance, this may help the owner feel better. If not, perhaps it is still possible to get it. At any rate the 300 gallon tank seems to be too much for the house andlikely should be taken down or at least remove a lot of the water. Good luck.
A 700 is not going to be a good idea in this house based on what you have posted so far. I hope you keep us up to date on this.
 
sk, thanks for the tips.
here in texas we have foundations. no basements. so he tank is directly on concrete.
but here we have had a really dry year wich makes our ground shrink in certain places that get less water.
when it rains here the water saturates the ground and it swells back up. a foundation expert told me this.
alot of people here use soaker houses around the perimeter of there house to prevent one side sinking more than the other.
the corner of this house was already sinking when we moved in but it seemed like when i put in the 300 it sunk a little more. it could have been that we were farther into the drought but im not sure.
i will for sure have a foundation expert look at any house we buy.
i just didnt know i there was a good aswer here or if anyone had some good advice.
and aslo the 300 is glass and the 700 will be acrylic. so im thinkin they will be about the same weight empty.
so a 700 gallon tank will weigh almost 4 tons?? :O
 
scalesandfins said:
so a 700 gallon tank will weigh almost 4 tons?? :O
Click to expand...

yup... one US gallon is 8.34lbs... so 8.34 x 700 = 5838lbs in just water. add about 600lbs of substrate, the weight of the tank and stand and any filtration equipment and 7000lbs is quite achievable
 
Hello; Sorry to hear that you are in a drought area. Saw a guy on TV saying that the drought conditions may be ongoing in areas of the west. The shifting of the foundation may have a lot to do with the drought and may not have happened under different conditions even with the weigh of the tank. At any rate this can be pointed out to the property owner. I know that in cold areas a foundation needs to extend below the frost line to prevent frost heaving. I do not know what to look for when dealing with drought. I was looking into having a slab poured for a garage. What is called a capital pour was recommended. That is where the peremiter of the slab is deeper/thicker than the cement in the middle area. This provides support for the walls like a footer and helps prevent edges from being washed out and undermined.

I use 10 pounds per gallon as a rough estimate for smaller tanks and stands with equipment and substrate and 12 pounds per gallon for larger tanks as they are made from thicker glass and the stands are usually made of sturdier stuff and are likely heavier. It also seems to take more gravel/sand and more equipment with the larger tanks. You will also have other things in a tank room as well as people in and out.

Thanks for posting more information. That helps me understand the situation. It is good to know that the 700 will be going into another building. One of the things I looked for when searching for a place was an attached garage. Folks around here often convert them into additional living space. They should make a good place for the heavier tanks as they should be on a cement slab. I did not get a house that way but did get one with a slab in the basement.

Flooding and excessive rain have been the problems around me of late. I searched the FEMA flood maps before buying and rejected a couple of places on the margins of flood zones. We had record setting flooding last summer with water in places where it had never been before. One thing you could do is to use the water from tank changes to wet down the area around the foundation, I have no idea how much water this will take. Take a good look at the foundation of any place you are thinking of buying. i imagine that there are signs to look for. Good luck.
 
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