Okay you construction experts, my builder says the floor will handle 40 lbs per squar

[6-line]

40 lbs per square foot. So what does that mean in tank language? I can't believe it means a 90 gallon tank is only 5-6 square feet....=240lbs? That can't be right...
He says he has no doubt the floor will support a 90 gallon or more and gave that figure (the 40# per square) What does that mean, exactly? How many square feet with a 90 gallon, 48"X18" tank?

Hope someone can help

[MrSandman]

That sounds a bit low IMO. 40#/sq. ft. means that if i were to stand on one leg on that floor, and being that i weigh 170 lbs., and my footprint is less than 1 sq. ft., i would fall straight thru the floor?? I doubt it. I think that number is waaay too low. Perhaps a civil engineer or construction engineer here would know what the required limit is? Is the 48"x18" dimension the footprint size of your tank? If so, then that means it has a 6 sq. ft. foot print. If my math serves me correct, that would mean that your floor can only handle 240lbs over that area. Impossible!! That building would be red tagged and i sure as heck wouldn't get in there.. :D
Something is not correct here.

[Fishrat]

a 48" X 18" footprint is indeed 6 sq ft. Are you sure your engineer didn't mean 40 PSI (pounds per square inch)? 40lbs per sq foot would mean that if you weighed more than 40#'s and stood in one spot, less than the size of a large floor tile, the floor would collapse under your weight. Perhaps he's added a huge safety margin to CHA?

HTH

Dave

[6-line]

Yeah,
I know, it didn't sound right to me, either.
Maybe he meant or did say per square inch.
He was adament in stating that he had no doubt the 90 or 125 could easily be supported anywhere on that level.
So, how many square inches in a 90 gallon tank foot print?
He had to mean that...he knows how much the tank weighs so he couldn't have been that wrong.
maybe I heard wrong...

[dnjan]

A typical residential loading is 40 lbs/sq. ft. That means your floor is strong enough for 40 lbs on every square foot. Or in other words, you can have your entire room filled with people (average 160 lbs) standing 2 ft apart.

So no, you won't go through the floor if you stand on one foot. But if you packed your room with people at tightly as they could fit (about 1 sq. ft. per person), you would be in trouble.

Back to the tank - if you covered your room with tanks all side-by side - big problem. Tank weight is about 70 lbs/sq. foot (including stand, etc.) for every foot of tank height. An 18" tall tank is loading a bit over 100 lbs per square foot. That is why people normally put tanks close to walls (in addition to convenience!) - the support is better next to the wall. Remember, the rest of the room is loaded much lighter, so the total loading in the room is still OK. And the heavier load (the tank) is in the best-supported location.

Is your floor strong enough - yes, as long you don't then cram the room full of people.

[mzem]

Keep in mind that if you are really worried about tank loads on your floor that you can put down a sheet of plywood larger than the footprint of the tank to spread out the weight on the floor. The larger the footprint the less weight per unit area thus spreading out the load. Believe me this works as we have to use this from time to time on the ship I work on. Deck loads become a safety issue on a ship. I understand this may not always be an option but the extra wood could be covered up by a rug or something too. I have used this in the past in apartments. HTH!

mzem

[tim4j]

I'm an architect and I deal with loads every day....the 40lbs he gave you is a live load. A fish tank is considered to be a live load (live loads are things that can be moved, ie, tanks, funiture, people, pets, etc). A house is designed to hold 40lbs/square foot of Live Load, and 60lbs/square foot dead load (Dead loads are parts of the house, ie, walls, roof, anything permantely attached to the structure). So truthfully a floor system can hold 100lbs/square foot. It will hold more, structuaral engineers will OVERDESIGN a structure.....mainly to cover their butts....so if they say 100lbs, it might actually be 150lbs per square foot. But there is no way to tell how much weight your floor is already holding?? So you will not know if you put a tank on the floor, it might or it might not put the load over board.....IMO I would not try to put anything bigger than 125 gallon on an upper floor without "beefing" up the structure. I have however seen 250 gallon tanks on the second floor before (which weight about 3000 lbs), and let me tell you, I was afraid to walk under it on the first floor!!

If your talking about only a 90 gallon tank, you'll be ok....Hope I explained that alright.....he is correct about the 40lbs though....but that isn't all the floor will hold....

[Guy]

I forgot one critical measurement when calculating the load for my 155. Everything went perfect until I had a party and had a dozen people standing right in front of my tank. My perfectly level tank had about 1" more water in the front than the back.

Needless to say, I added some more support under the tank in the basement....

[6-line]

Okay,
Thanks people, that cleared some things up.
It will be against a weight bearing wall and I will place a sheet of plywood beneath it. How much, though? I figure the tank will be 6 inches from the wall, so perhaps a sheet that will run to the wall and maybe 6 inches beyond the stand (figure a 18-20" stand). I plan on putting Linoleum down on the plywood for decorative purposes.
Thanks