New installation / No a new Hobbits

[Pump_Guy]

Good Morning/Afternoon Guys

I used to live in another country and had a nice aquarium setup back then. Unfortunately, I had to give up the hobby in 2014 when I moved to the U.S. I was active on this forum before under the username Carloss, but I couldn’t recover my old account, so I’m showing up as a new user now.

Now that I’m in Aurora, Colorado, I’ve been bitten by the reefing bug again and I’m thinking about starting up a new 120‑gallon mixed reef (48" × 24" × 24").

I estimate the total weight will be around 1,500 lbs—and that’s where my concern comes in. The tank will be located in my living room, which sits above a crawl space. From what I’ve read, typical U.S. homes are built to support around 40 pounds per square foot, which is well below the load I’m talking about. The good news is that the wall directly behind the aquarium sits over a structural steel beam that’s supported by another beam resting on a concrete slab. The entire floor is supported by wooden joists spaced about 12" apart.

I had a pre-consultation with a structural Engineer, but he was charging me $1,000 to do an On Site inspection, that is no-gonna-happen.....

I’ll attach some pictures later—they might make everything easier to understand. Any advice or guidance would be much appreciated!

 

[griss]

Yes, a picture of where you would like to locate the tank as well as the underside of the joists would be helpful.

Also, your old account is still active. @JohnL may be able to help you reactivate it.

 

[Uncle99]

Good Morning/Afternoon Guys

I used to live in another country and had a nice aquarium setup back then. Unfortunately, I had to give up the hobby in 2014 when I moved to the U.S. I was active on this forum before under the username Carloss, but I couldn’t recover my old account, so I’m showing up as a new user now.

Now that I’m in Aurora, Colorado, I’ve been bitten by the reefing bug again and I’m thinking about starting up a new 120‑gallon mixed reef (48" × 24" × 24").

I estimate the total weight will be around 1,500 lbs—and that’s where my concern comes in. The tank will be located in my living room, which sits above a crawl space. From what I’ve read, typical U.S. homes are built to support around 40 pounds per square foot, which is well below the load I’m talking about. The good news is that the wall directly behind the aquarium sits over a structural steel beam that’s supported by another beam resting on a concrete slab. The entire floor is supported by wooden joists spaced about 12" apart.

I had a pre-consultation with a structural Engineer, but he was charging me $1,000 to do an On Site inspection, that is no-gonna-happen.....

I’ll attach some pictures later—they might make everything easier to understand. Any advice or guidance would be much appreciated!

Pics will be great. What size beams and how many under the load?
I’m 2000lbs in 12 Sq/ft footprint in a 20’x15’ living room.
I put a 2x4 brace under the front of the tank to be sure.
The 40lbs/sqft assumes the load is spread out.
A large fish tank of course is much more concentrated.

 

[Pump_Guy]

Pics will be great. What size beams and how many under the load?
I’m 2000lbs in 12 Sq/ft footprint in a 20’x15’ living room.
I put a 2x4 brace under the front of the tank to be sure.
The 40lbs/sqft assumes the load is spread out.
A large fish tank of course is much more concentrated.
View attachment 32417187

I don't understand the "40lbs/sqft" either, It seems too little, or I am in a big problem. I was thinking about supporting the subfloor but i don't have a basement like yours, I have a "tall crawl space", so the ground it not concrete, is that black membrane that is over dirt. I will share some pictures when I get home.

 

[Uncle99]

I don't understand the "40lbs/sqft" either, It seems too little, or I am in a big problem. I was thinking about supporting the subfloor but i don't have a basement like yours, I have a "tall crawl space", so the ground it not concrete, is that black membrane that is over dirt. I will share some pictures when I get home.

The 40lbs/sqft load is calculated as follows:
40 x (room square footage)
40 x (10’x 10’) so designed to hold approx, 4,000lbs but, the calculation assumes the loads are spread out, not concentrated in one area like in a fish tank.

Sizes and types of beams will be important.
12” centres like you state are great, but what’s the size of each beam and how many will be directly under the loaded area.

 

[Pump_Guy]

 

[kharmaguru]

12" TGI is stronger than conventional lumber which is great but that spacing is over 16" ( I assume you are hooked on). Is it all like that? Also see if you can find any stamps on the bottom of the subfloor. If it's 3/4" tongue and groove that adds a ton of strength and stability. You should also be able to see some construction adhesive squeezed out from between the subfloor and the top of the TGI joists.

 

[Pump_Guy]

Yes. All is like that.but did you see the 10” steel beam?

 

[kharmaguru]

Yes. All is like that.but did you see the 10” steel beam?

Is the tank going to be close to the beam?

 

[Pump_Guy]

Is the tank going to be close to the beam?

Very close

 

[kharmaguru]

I'm not an engineer but I regularly work with the materials your floor is built with. I've given you things to look for to know it was built properly and give you piece of mind, but building codes and habits vary obviously. I don't love the joist spacing as that makes me question if other corners were cut to save materials. Do I think it's going to collapse? No. Will something sag over time? That's a question I can't answer.

 

[Pump_Guy]

I'm not an engineer but I regularly work with the materials your floor is built with. I've given you things to look for to know it was built properly and give you piece of mind, but building codes and habits vary obviously. I don't love the joist spacing as that makes me question if other corners were cut to save materials. Do I think it's going to collapse? No. Will something sag over time? That's a question I can't answer.

Thank you Sir.