Any Engineers Out there - Load/Weight Question

My wife and I live in a Mobil home and currently have a 72g tank W/Fuge thats been set up for over a year.

My Question is in regards to someday upgrading to a larger tank somewhere in the range of a 150-180g tank and replacing the 72g. My concern is how much weight there is in the change and if our current place will accommodate over double the weight. When I go under our Mobil the house is on a steel understructure and I'm not sure how much weight they are rated to hold. The home was build in the mid 80's if that helps.
My other question is if I put supports under the tank should I support the steel beams or the wood directly under the tank to take pressure off the structure itself?

Thanks

Starting to dream already, everyone should have a 5 year plan, lol

 

I would consult the manufacturer of the Mobil home, if possible.

 

yeah i would definitely contact the manufacturer..as for the weight..water weights about 8 pounds per gallon..do that math..then double your rock/sand weight..if it does come down to reenforcing your flooring you could find out what people do when they get hot tubs..I know of a couple people who have had to add supports for those

 

Another thing to consider is getting under there and reinforcing the beams and adding extra foundation points where the tank will be. That's something even home-owners with crawl spaces often have to do with larger tanks.

 

Finally one question that I'm for sure I can answer!

Being a general contractor its my job to know how homes are put together.
So this is the basic deal, it really depends on the age of your mobile home. Homes built before the early 90s use 5/8 inch (1/2 if older than 1979) OSB plywood. If I'm correct the underside of your home consists of I-beams, and inbetween your i-beams are your 2x6 joists. The rating of load for a 5/8 piece of OSB supported DIRECTLY by the floor joist is about 350lbs per square foot.

Now, not knowing what the underside of your home looks like directly, I would take double 2x6 joists (nailing them together) and run them directly under where you plan on putting your tank. By supporting the ends of the 2x6 joists with some hanger brackets (made by simpson, and you can get it at any home depot or lowes) it will easily support the new load of the tank. You just need to be leary about getting around your support jacks under the house, unless of course your home is on a foundation.

If you can take some pictures of what the underside of where your working is I can walk you through with what you need. PM if you want to take me up on it.

-Gavin

 

Thanks for the input everyone,
Da_Gopherboy, as soon as I have time to take some pics ill forward them to you to see what you think.

cat4wisson

 

The "ME" stands for Mechanical Engineer
150g-180g is 1250-1500 lbs in water weight alone. Density of wet sand is roughly twice that of water - so about 1950 kg/m^3. Instead of getting into exact numbers though, I'd assume a worst case total weight of around 2500 lbs. That should cover your equipment, stand, sand, rock, and leave a fairly large safety factor in the case of warped wood from flooding or something... are you accounting for a sump/refugium? No sump/refugium?

In addition to what Da_Gopherboy said, I'd also look into adding some diagonal supports on the inside of the stand's walls. This is a cheap and easy way to make sure your force is distributed uniformly around the tank footprint's perimeter. Seems excessive, but like I said... it's cheap and easy.

Good luck!