Tank Weight and Floor Joists

JodiI · Jun 13, 2020

So my husband and I are closing on our new house in just under two weeks. Brand new construction out by Aurora Reservoir. We're going to use some of the proceeds of the sale of our current house (plus some cash) to buy the tank for my dream build.

So for 8 months, I've had my heart set on this one: https://waterboxaquariums.com/products/peninsula?variant=31713747828845

We even had the builder dedicated electrical run to the tank's location in the new house. They laughed a little when I told them the reason, but whatever.

Here's where I need your opinions. Turns out the the tank will be sitting parallel with the floor joists. Would you put a 220g tank parallel to the floor joists? Based on the size, I think it will be sitting on one or MAYBE two floor joists. However, the wall it will be up against backs to the garage - so the joists will be at their strongest (unless my understanding is off).

I've really had my heart set on the peninsula tank for so long. If the consensus here is that it isn't wise to put that much weight on one (two if we're lucky) joists, then I'll have to pivot to this tank instead: https://waterboxaquariums.com/products/reef-pro?variant=31519404294253 Basically, same tank - just not a peninsula.

I'm curious what the hive mind thinks.

JodiI · Jun 13, 2020

You can see house floor plan here: https://imgur.com/a6lGlYK

Yellow is footprint of tank if peninsula. Blue is footprint of tank if non-peninsula. 6 foot tank either way. The garage obviously is full concrete and foundation wall. The light grey is the way the floor joists run (though not the actual location of the joists).

halmus · Jun 13, 2020

Couple of questions for clarification:

What are the dimensions of the “Study”?

Is there a basement under the Study or a crawelspace?

If basement, it it finished?

I’m wondering if there’s a basement, could you reenforce the outer perimeter of the joists with somewhat temporary posts while the tank is in place and still leave it open to future remodeling if the tank is no longer in place overhead? Possibly can do the same with a crawl space. I would make sure the tank is over at least two joists in that scenario.

I’m also wondering the dimensions of the study. I obviously love peninsula tanks. I have one. However, if the peninsula makes the rest of that room almost unusable due to dimensions, maybe that’s not the right route to go? For instance, are you planning on a desk, chairs, or couch in that room to enjoy the tank?

Possibly, make a mock tank out of cardboard and place some lawn chairs in the anticipated configuration and see how it looks, feels, functions.

JodiI · Jun 13, 2020

halmus said:

15'2" x 12'6" - same as shown on house floor plan. I also "borrowed" the blueprints for the house. So I do have a copy of the joist locations. Sadly, those plans are currently in a box somewhere.

halmus said:

Yes. Finished. There is a bedroom directly underneath the location of the tank.

halmus said:

Sadly, this is not an option. Tearing out the room beneath the tank is not on the agenda.

halmus said:

The peninsula will almost exactly divide the room in half. We have two computers (and two computer desks) which will also go in this room. We have locations for both of those with either scenario. This is really the "hobby" room, if you will. Visible from the main living area, but not necessarily part of the main living space. Putting the tank in the main living area was not an option due to other considerations.

halmus said:

We do have plans to tape out the floor just to make sure. If we determine that the 6 foot tank is too long, Red Sea has a 5 foot peninsula option. But obviously, I want the 6 foot if possible.

Husband is really mostly leaving this up to me - his my best enabler/biggest fan.

So my main concern is that this is our dream house - I don't want to do ANYTHING that would compromise the structure. We plan to be here into our old age. At the same time, this is my dream tank. So I don't want to compromise on the tank if I don't have to.

TheRealChrisBrown · Jun 13, 2020

Personally I'd feel better with it not being a peninsula and being a 6 foot tank on that wall. I'd want to hit as many joists as possible, and even then - conventional wisdom used to be 150g or 180g was about max when not being on solid concrete. The larger tanks I've seen on second floors or above a basement or crawl space have usually been reinforced from underneath with steel posts and some kind of beam running across the joists to further carry that load. A 180g tank full of rock and water tops 2000 pounds....I'd really think that weight is better spread over 4 joists than 1 or 2. I think having it next to the garage is better, but that's still literally a ton of weight.

neil82 · Jun 14, 2020

Super nice tanks you are considering and congratulations on your soon to be new home. I was looking into this topic recently as we just moved to a new construction home as well. I was looking at putting a 90 gallon 4 foot tank on 1st floor above basement. Placement was against a wall parallel to joists. Estimated total weight 1200 lbs with weight of glass, rock, sand, sump etc.
I went down to basement and looked at the joists. They are Boise Cascade BCI 5000 1.7 series joists. I looked up manafacturer spec guide which is here: https://www.google.com/url?sa=t&sou...FjAAegQIBBAC&usg=AOvVaw0MZt05gXJyfQv73fHkO91h
On page 10 there is an allowable uniform floor load table. The span length of the joists for my application was 17 feet. Oh, and our joists are the 11 7/8th inch depth. Looking at that on the chart, it's saying 55 lbs per linear ft live load or 87 lbs per linear ft total load. My tank would have sat over 3 joists (our joists are spaced at 16" and every other one is a double joist) and parallel to the joists. 4 foot tank resting over 12 total linear feet of joists. Using 87 lbs per linear ft total load figure from table times 12 linear ft equals 1044 lbs. In my mind this was the maximum load. I did not feel comfortable placing 90 gallon setup there for this reason. Also, the placement was right in the middle of the 17 ft joist span, which is not ideal.
I'm not sure if I am interpreting the table correctly and making the correct calculations, but that was my best shot at it.

neil82 · Jun 14, 2020

But back to your scenario...

In my opinion, only potential option is against wall perpendicular to joists. But that is probably still pushing it. You would need to have it checked out by a structural engineer. Any chance to potentially put tank in the basement?

NickP · Jun 14, 2020

I had a 180 on the 3rd floor of an 1980s townhouse cross 4 joists next to the outer wall with no issues. Estimated tank weight at 2500#. Would not be comfortable with it on two. Had a construction buddy check out the joists before hand, was like ur good those are commercial. Which was 2 2x4 laying flat and in between them a vertical 2x4 and angled 2x4 on each side of the center 2x4 down the length of the span.

JodiI · Jun 14, 2020

neil82 said:

Only if we never want to see it. The basement was finished by the builder for free as an incentive - we don’t plan to use it for a very long time. The house is larger than our current needs. So it doesn’t make sense to put the tank in an unused part of the house.

Sent from my iPhone using Tapatalk

JodiI · Jun 14, 2020

neil82 said:

Super nice tanks you are considering and congratulations on your soon to be new home. I was looking into this topic recently as we just moved to a new construction home as well. I was looking at putting a 90 gallon 4 foot tank on 1st floor above basement. Placement was against a wall parallel to joists. Estimated total weight 1200 lbs with weight of glass, rock, sand, sump etc.
I went down to basement and looked at the joists. They are Boise Cascade BCI 5000 1.7 series joists. I looked up manafacturer spec guide which is here: https://www.google.com/url?sa=t&sou...FjAAegQIBBAC&usg=AOvVaw0MZt05gXJyfQv73fHkO91h
On page 10 there is an allowable uniform floor load table. The span length of the joists for my application was 17 feet. Oh, and our joists are the 11 7/8th inch depth. Looking at that on the chart, it's saying 55 lbs per linear ft live load or 87 lbs per linear ft total load. My tank would have sat over 3 joists (our joists are spaced at 16" and every other one is a double joist) and parallel to the joists. 4 foot tank resting over 12 total linear feet of joists. Using 87 lbs per linear ft total load figure from table times 12 linear ft equals 1044 lbs. In my mind this was the maximum load. I did not feel comfortable placing 90 gallon setup there for this reason. Also, the placement was right in the middle of the 17 ft joist span, which is not ideal.
I'm not sure if I am interpreting the table correctly and making the correct calculations, but that was my best shot at it.

This is really good information. I also found this article last night which was helpful.

http://www.african-cichlid.com/Structure.htm

I still have access to all of this information about my home, so I think I can reasonably follow your process here to get an estimate. At least to see if it’s necessary to hire an engineer.

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neil82 · Jun 14, 2020

JodiI said:

In that article, it looks like they give a general rule of 40 psf for live load in residential structures.
I think in my example, I underestimated the load capacity since there was a 'double' joist involved and I believe the specs would be for single joists at 16 inch spacing. But I wanted to play it safe since it was also in the middle of 17 ft joist span. Or if I interpreted the load calculation as: 87 lbs per linear ft and multiply by 17 ft, then each joist could hold 1479 lbs and I had 3 joists under the tank. But then I would need to include the weight of any other furniture and appliances resting on those joists as well. That article you linked also stated:
And that leaves the worst possible position for an aquarium which is parallel to the joists in the mid span of the joists in the room with the longest joist span.

That's pretty much an exact description of where I was considering placing the tank, so I was going with the most conservative approach with my calculations.

You'll want to find out how long those joists span for your application. I think we know they are at least 12.5 ft based on your floor plan. Maybe there is a steel support beam running under that wall dividing the study and kitchen?
Sorry if all this seems like it is taking the wind out of your reef tank sail. I've totally been there. But it's worth some careful consideration since you are making a significant long term investment with your home and also a large investment with the tank as well. Keep us posted with what you find out and how you decide to proceed. I'm really hoping your dream home and dream tank will both be possible for you!

JodiI · Jun 14, 2020

neil82 said:

There is indeed a steel support beam between the study and kitchen.

We haunted the construction site so often, I know where all the beams are located.

Funny story though - my husband looked online and hiring a structural engineer to assess it would cost about $80 an hour. So we were about to post up online asking for someone, when I figured I should text my family. I have two sisters and one sister-in-law that are all civil engineers, so I asked them if they knew a structural engineer who could look at the house for us (and we would pay).

Apparently, that was an offensive thing to ask, since two of these women currently work or previously worked for structural engineering firms. Haha. Short story is that my sister is going to look at the house plans tonight and let me know. Free structural engineering assessment! I'll let you guys know what she says.

JodiI · Jun 14, 2020

Shows how much I know about the various types of engineering. Pays off to have a lot of math/science women in the family.

SynDen · Jun 16, 2020

If you place the tank like the blue line in the pic, then I think you will be more then fine with the 6ft tank. The yellow position though likely would work fine too but I would want to add at least some reinforcement for it, or it might sag a bit over time.
If you have a room under neath, one option could be to pull out some of the ceiling, and then sister in some boards along side the existing supports. Then replace the ceiling after. Doubling up the support that way can add more then enough extra load bearing to handle just about any sized tank, and wont leave you with a steel pole in the middle of the room.

JodiI · Jun 18, 2020

So we got the structural engineering assessment back.

My sister wanted to do the assessment, but she's currently 9 months pregnant and we just helped her family move into their new construction home yesterday. So I told her we were just going to hire it out since she's got a lot on her plate right now.

We used this website: UpWork to hire a structural engineer to analyze our floors and determine the weight we could carry. I HIGHLY recommend this site if you have any questions about your aquarium and floors - it was very easy to use and very reasonably priced. We paid an engineer $80 an hour to give us the assessment.

He analyzed our blueprints and determined that the 6 foot tank along the wall passed and would bear the weight. It was definitely heavier than the house was designed for, but it passed. The peninsula tank would also be held by the floor as long as it was across two joists (not centered on one - our joists are 16 inches apart), and we would need to open up the ceiling on the room below and put in some blocking. The engineer sent us all these technical designs and stuff that I can't really read. Haha. Thankfully he also summarized it, and my sister confirmed based on his math.

Since both tanks are beautiful, we're going with the non-peninsula since we're not keen on tearing apart a finished room. The non-peninsula also comes with benefits in the ease-of-providing-flow category.

Thanks everyone!

TheRealChrisBrown · Jun 18, 2020

Nice! I just uploaded a job on UpWork to see if I can get a structural engineer to evaluate/sign off on my roof for solar. Thanks for the suggestion!

flagg37 · Jun 18, 2020

One quick thought; would you entertain the idea of having the peninsula tank on the mud room wall? It could fit right next to the door and that way it would be perpendicular to the joists.

JodiI · Jun 18, 2020

TheRealChrisBrown said:

Nice! I found it a great experience!

JodiI · Jun 18, 2020

flagg37 said:

I did think about that. After the house was built and I got to actually see the room in person to realize there might be a weight issue.

The reason I don't want to do that is because I had the dedicated electrical run to the garage-side wall. And I don't want to run cords across the room. The water change station will also be in the garage for auto water-changes, and I don't want to look at those cords either. If I had thought of that idea sooner, we probably would've made that happen. But too late to change anything once the drywall goes up.

neil82 · Jun 18, 2020

Thanks for sharing the results of the assessment. Hopefully that comes as good news. Like you said, they are both beautiful tanks!

Tank Weight and Floor Joists

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