Maximum load on floor

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  #1  
Old 05-07-05, 05:44 PM
LBC
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Maximum load on floor

I am looking to purchase a large aquarium and was wondering if my floor can withstand its weight. I own a bungalo that was built in 1957 and it has 2x10 floor joists supporting the main floor, these joists run 16' from the concrete foundation to the center beam. The aquarium would span 2 of these joist for sure and depending on the stand design it might reach three, but it would be real close(the tank is 48" long). The tank would sit within 3 feet of the outside wall.

Oh ya, the tank could weight as much as 1500 pounds. 120 gallons+stand+light setup+etc...

Thanks for your help.
 
  #2  
Old 05-08-05, 08:43 AM
J
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No!

Your floor is designed to support about 40 lbs/sq.ft. An aquarium of this size will place a load of about 5-6 times that much on the floor in that area. The only way such items should be installed is with their own independent support. If you can install a concrete footing(s) directly below this area with 2 4x4 posts and a 4x6 girder should be OK. Otherwise forget it.

You will also want to make sure the subfloor is backed by solid blocking where the stand sits on the floor (particularly if there are legs as opposed to a solid perimeter).
 
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Old 05-09-05, 03:09 PM
LBC
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Well I decided to go with the 120gallon tank anyway. I figured that the 40#/sq ft rule probably has a safety factor involved. Also I am not worried about the subfloor because the tank is going to be sitting on hardwood floors. So far I don't see or hear any bending or cracking of the floor joist downstairs, although I do believe the tank's weight is only sitting on 2 joists. I decided to put a piece of plywood up to help hold the weight...

This tank is 6ft*2ft long so it works out to being about 125#/foot and that ends up being about 3 times the working weight allowed on the floor. What is the safety factor, 10X?
 
  #4  
Old 05-10-05, 05:20 PM
P
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I've never had any trouble with standard sized tanks up to 110 gal. but I always had them placed right up against a wall that had a load bearing support (wall or foundation) below them and the tanks were situated to hit as many joists as possible. I've never tried having a tank larger than 20 gal. in the center of a room or sitting parallel to the joists where it's weight would only be carried by one or two joists. That said, a large tank is a lot of weight sitting in one spot. What will make it worse is when you have a party with ten people in the room also standing on the same floor joists that are supporting your tank.

By the way, what kind of tank are you setting up?
 
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Old 05-11-05, 01:25 PM
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if your tank was 6' x 2', you'd be able to support 480 pounds regardless of where you placed it.

There is no real "margin of safety", at least no where near what you are proposing.

However, the code recognizes that some areas of a floor are loaded heavier than others, ie: a bookshelf weighs more than 40 pounds per square foot, but the area in front of it where you stand is receiving no live load. It averages out. But you are at 3x the load. That's probably beyond the margin of safety.

You should use that special "light weight water"

I have to admit - this sounds too heavy for your floor to me. I'd plan on a smaller tank, or put it in the basement, or build a special structure for it.
 
  #6  
Old 05-11-05, 03:15 PM
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Safety Factor

Just for the record, the code does not allow for exceeding the design load.

Standard engineering practice is to calculate an ultimate strength capability divided by 2.5 ( So that's your so called "safety factor" ). But the code doesn't allow you to exceed the design load - you're asking for trouble.

 
  #7  
Old 05-12-05, 07:07 PM
LBC
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Originally Posted by Pilot Dane

By the way, what kind of tank are you setting up?
It is going to be a planted South East Asia biotope tank. Clown loaches, barbs, rasbora etc and a nice aquascape.
 
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Old 05-12-05, 08:38 PM
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lbc,

For most species of wood you are already stretched to the limit. My simple solution/suggestion would be to go underneath and add a second joist sistered to the first along the width or length of the tank whichever is perpendicular to the joists. I would nail the two joists together with 16d's @ 8" o.c. staggered. I would then solid block both edges of the width of the tank so that the tank has solid bearing all 4 sides. This is often much simpler than running another girder line and piers.

I hope this helps.

Brian Garrison
General Contractor/Professional Building Designer
 
  #9  
Old 05-13-05, 10:17 PM
C
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your floor will tell you when it is working too hard.

put in the tank, and just keep an eye on it. if you notice some sag in the floor, you will have to do something else. the risk you run is permanently deflecting the joists a little which may take a bit of work to fix.

nothing is going to come crashing down.
 
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Old 05-15-05, 12:00 PM
L
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A could hundred dollars and a few hours to beef up the floor BEFORE you install the tank, or thousands of dollars and several days to fix it if you're wrong.

It's your call!!
 
  #11  
Old 05-16-05, 02:54 PM
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clardl,

I would hate to have the responsibility of a fish tank falling through the floor.
LBC does not say from which state is home. LBC does not state from which tree the joists hail from. I looked up the span chart and gave the benefit of the doubt to Douglas Fir. What if it is redwood which has the strength of spaghetti? The ole addage of dont fix it till its broke is not what he asked for.

The risk you run is having your fishtank in the basement or crawl space. Of going underneath a house in the now mud to pick up your fish, fish tank, and framing.

Everyone with a suggestion addressed solutions to the framing members. Even if all that happens is permanent floor sag at some point it goes right back to blocking, sistering, supporting something. There are a hundred ways to do anything in construction and i would never claim mine is the best, it is one of many but wait and see I could do without asking for help on the forum.

Brian Garrison
 
 

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