how can i tell how much weight my floor will hold?

[Madman133]

hey anybody know a good way to tell how much weight my floor will hold? My room is about 12x13 and on one side is a 55 and im thinking about getting 90 or 125 or something like that. It would be placed on the opposite side of the room if that makes a difference. Also our house was built in the early 90's and directly below my room is the garage. Also is custom built and not a track home if it makes a difference. I think we got the original blueprints around here someplace so ill look to see if there are any beems running underneath the room. But anyways would a stadard nonreinforced floor be able to support that?

 

[miwoodar]

You can typically figure out which way the joists go by looking at the roof. They will be perpendicular to the peak. You should be fine, especially if you can position the tank so it overlaps as many joists as possible.

Like this:
http://hartmanufacturedhomes.com/images/nuhartconstruct1small.jpg

 

[Rcpilet]

Typical floor joist spacing is 16" on center.

Floor joist vary in depth from 8" up to 24". Obviously, a 16" joist will carry a bigger load than an 8" joist.

Go down in the garage and look at the drywall on the ceiling. Look at the screw pattern where the drywall contractor installed the drywall. They follow the joists when the screw the drywall on. They screw into the joists. That will tell you which way the joists are running.

You'd want to span 3 or 4 joists AT LEAST to support a fish tank.

Water weighs 8/lbs per gallon. Figure a 125g tank weighs about 100 lbs. You're EASILY looking at 1000 lbs just for the tank, stand and water. Add a couple hundred pounds of rock and other junk. You could be looking at 1500 lbs for a 125g tank. It's probably more like 1100 or 1200lbs, but give yourself some safety factor.

Would I put a 1500 pound tank on a regular floor without reinforcing that floor? NO WAY!! Not unless you got flood insurance on the cars. :lol:

You might have to take the screws out and pull down a couple sheets of drywall. Measure the depth of the joists. Go to the bog box lumber store and buy a 2x10 stud or 2x8 stud to match up to the existing joists. You'll have to run the additional joists from the bearing wall to the nearest beam of supporting column. Nail/screw/bolt them in with joist hangers or angle iron pieces.

If you REALLY want to reinforce the joists, call PM me with your phone number and a good time to call. I'll explain how to do it. I've worked in construction my whole life, so I have a pretty good handle on how to "scab" a couple studs or joists into an existing house for reinforcement.

 

[miwoodar]

I agree with rcpilet that you definitely do NOT want a spillage. I think you should consider how a 125 compares to other tanks though in terms of pounds per square inch (PSI). If a 125 weighs 1500 pounds and has a footprint of 1296 square inches (72 x 18)...you are looking at 1.15 PSI.

Comparing this to another common tank size....My 65 is half as long as a 125 and has the same width and height. The PSI is virtually identical. Would you think it is necessary to add additional support for a 65? Have you ever seen someone install extra supports for a tank as small as a 65 (I haven't)? Just because you see a bunch of people here on the forums installing ultra supports for their tanks does not mean it is necessary.

I absolutely agree 100% with Rcpilet regarding the joists though. You definitely don't want to put all this weight on one joist by choosing the wrong wall. Find a place that will let the tank span as many as you can get.

 

[Madman133]

hey thanks for the advice guys. Ill ahve to to see which way the joists are running and i have a feeling its the wrong way. Also what about a corner tank? i saw a 100 gallon corner tank on craigslist earlier and im guessing that would prabably be worse than a 6 foot tank as it wouldnt be suported by as many joists. Is my thinking correct? or would it be better since its in a corner and close to two walls?

 

[miwoodar]

What are the dimensions on it?

 

[gjm258]

Here! Ask the architect(ural intern)
<---------------


Will the floor hold as is?... most likely.
Will the floor cave in? ..... if pigeon crap can make a bridge fall down, an aquarium can make your house fall down (that would make for a great news story! "home aquarium caused catastrophic failure of a home in Colorado. One toy poodle is lost in the rubble")
Will my house fall in on me? .... you will probably win the lottery first


Most importantly!
Is it better to spend a little money to throw in a few extra joists.... absolutely 100% yes.

If you can blow $1000's of dollars on fish, you can spend a couple hundred on structural reinforcement.

 

[miwoodar]

If gjm258 is studying architecture - you should consider his advice. I'm an engineer but I focus on remediation of hazardous wastes, nothing to do with homes or home construction.

I've had 125's on truly questionable floors in the past though without incident. The homes were old construction and their build quality was clearly sub-par.

Myself, I wouldn't tear into an existing floor for a tank that is 18" front to back to add joists unless I was in the midst of a project that had already exposed them. I wouldn't rip up a hardwood or tile floor if I didn't have to. I would be more concerned about not getting it to match the rest of the room when I put it back down (could be expensive too depending on the materials used). Carpet, I hate it, if anything, I might actually use the joists as an excuse to rip it out.

 

[denverhoss]

Another thing to keep in mind is how the walls in the basement line up with the walls in your room. If they match up (the garage wall directly holds up the room wall) then placing the tank against the wall (as most tanks are) greatly reduces the chance of the floor sagging under the weight. If the room wall is just a divider that does not have a nearby garage wall matching it, then there is little or no extra support for that part of the floor. Basically, if you are near a supporting garage wall then much of the tank weight will be transmitted almost directly to that wall â€"œ which is good. If you put the tank in the middle of the room, or near a wall that is not supported in the garage, then you have to transmit that weight horizontally across the joists (as many as you can) and over to the nearest wall or support post. This can cause the joists to sag (probably not break). The affect can be seen by putting a wood yard stick between two chairs â€"œ hanging a hammer near one of the supporting chairs has little affect, but hanging a hammer from it in the middle causes it to sag noticeably.

That said, note that I’m no carpenter! But my feeling is that if you’d put a water bed in that room without thinking about it, a reasonable size tank sitting near a supporting wall and across several joists shouldn’t be an issue either.

 

[miwoodar]

Good point denverhoss.

 

[Madman133]

ok thanks for the advice guys...denverhoss it is a supporting wall that it would be next to but the other 3 arent. I will let you know what i decide. Im still having trouble with the money another tank is going to cost though lol. I still lie to myslef about how much ive spent on my existing one lol.