Floor and tank weight

[Big_Boss_77]

Honestly if you think about it, even some of the largest tanks aren't that heavy relative to the overall size. I had a contractor/builder explain to me that most tanks are no heavier on one spot than a 220lb man standing there.

If your floors cannot handle a 220lb man, you have a different set of issues. The weight is spread out. Putting them against a wall also helps with support.

Probably an oversimplification but not something I worried about. I have a 180 and 55 gallon sump on the second floor.

Yeah, this is a gross over simplification. (Not derogatory, just implying that this stuff is very complicated apparently) Tell your 220lb buddy to fill the footprint of your tank and stand there for the next 10 years, most tanks weigh much more than 220lb though. I forget the exact terms but I just went through this this past summer. My floor wouldn't hold the 220lb guy passing through gingerly, let alone stomping.

I had to replace the whole subfloor and in doing so got a crash course from the guy doing the work. It basically boils down to the difference between a temporary load and a load that will be there indefinitely. Two different loads equal two different types of strain on your floors. Make sure you're running perpendicular to your floor joists and along a load bearing wall or as close to the footer as you can. The strain increases exponentially the further you get from those and the longer it stays there.

Hope this at least gives you something to help aim your curiosity if not an answer to your question!

 

[RichK]

Look at the room from outside. Whichever way the roof slopes is the way the floor joists are running.
They should in most cases run from sloped side to sloped side Not from the flat(gable) side
Hope that makes sense.

I'm afraid that is not always correct. I just had a 16x24' addition built onto our split level and the joists run from flat wall to gable. This room was built with the tank in mind and the architect had the builder use double 2x12s where the tank will sit. The tank will span 4 floor joists. We also added supports under those double joists to the slab which is about 12" below the bottom of the joists. It's probably overkill. But I'd rather over build to be safe.

 

[keithhays]

You will want to call a local building contractor who will ask you the weight and the exact footprint and location in your house. After he looks at the structure and does some calculations, he will let you know what to do. Don't pay an engineer extra. If the contractor will be doing the work, he isn't going to charge you extra for the calculations.

I have multiple footprints, but my primary footprint boarders a laundry room wall.
That wall has structural supports directly under it and the outside wall of the house borders the other walls in the laundry room with only 7 feet between the walls, so everything that I put in the room secondary sumps, multiple 55-gallon water containers etc. were fine.

On the other side of that same wall in my living room, My multiple aquariums however are sitting in a 6ftx2ft footprint holding about 370 gallons of water and several hundred pounds of glass, rock, cabinet, etc. The total in that 6x2 footprint is about 4000 pounds of dead weight and required concrete piers and large wooden beams to be placed in the crawl space.

Be sure that when you give the contractor the weight, you add in the weight of all the other items and not just the saltwater weight or you will be way off.

If you need modifications, they will not translate into other areas of the house, i.e. he is not going to modify the entire structure of your house, just where you are going to put the tank.

ps. make sure the building contractor is a reputable builder of houses and not joe bob's fly by night contractor service. Also, don't bother calculating live weights that you see on the internet for floors, it doesn't apply to this issue. i.e. the 220lb man thing. You floor may hold the live weight for while, but will likely fall through in a couple months when the dead weight is felt by the structure.

 

[SGT_York]

In order to calculate the weight an engineer may do several approaches to determine the load capacity.

First and the easiest is a correlation of curves where they take the age of the home compare it to the designed codes of the day it was built and assume the home was built to minimum construction codes at the time. That will give you your live load capacity.

There are many assumptions and the estimate is overly conservative. It is the preferred method for 120G tanks and below. (which is why I wouldn't recommend calling an engineer unless you have a specific reason to like damage to the home or it's really old 1920 or earlier)

If you have a larger ~180G tank or above an engineer will do an actual engineered approach, they will take the distance of the span the size of the joists and stringers, the distance between each, verify the plywood or planks are adequate, factor in the weight of the house (two/three story?) and give you your load capacity. This is a much better approach but it requires either the structural drawings or removing drywall to see the supports. Not a very feasible solution for a finished living space.

Generally if you home is 1960 or later, in good repair and your 180G tank is running perpendicular to the joists you don't need to contact an engineer unless you have a specific reason to, a 120 parallel with the joists will be fine. (this assumes your home is built to code)

 

[OrQidz]

The 220lb man thing doesn't make a lot of sense to me either. For one thing we are talking like 5+ 220 men with a big tank, but the floor can sag over time or flex, and those really bored (they've been standing there for years!) men aren't going to crack at a seam somewhere and dump a hundred gallons of water all over your floor.

On a more serious note, can you safely assume that your external walls are load bearing and that putting tank against that wall will ensure it's perpendicular to the joists?

 

[woodnaquanut]

The 220lb man thing doesn't make a lot of sense to me either. For one thing we are talking like 5+ 220 men with a big tank, but the floor can sag over time or flex, and those really bored (they've been standing there for years!) men aren't going to crack at a seam somewhere and dump a hundred gallons of water all over your floor.

On a more serious note, can you safely assume that your external walls are load bearing and that putting tank against that wall will ensure it's perpendicular to the joists?

First off, I'd bet 5 guys standing in one spot for years will leak too! :lol:

Not all external walls are load bearing. Usually gable end walls are parallel to the joists. If you are in between the joist supports on this wall there could be trouble.

Also if you are not putting the tank on an outside wall, a common occurrence, you have to do some exploration to find bearing walls. Bearing walls always have support under them -a beam perpendicular to the joists or a foundation perpendicular to the joists. To see this you need to view what's under your proposed location. If you are in a second story room, look at the room below and it's supports. If you are on the ground floor look in the basement or crawl space. For crawl space situations sometimes you can look into it from the vents and save a creepy crawl space visit.