I am building a reef tank in my living room, it's in the corner of the house, and as you can see from the drawing, it is sitting on 5-floor joists. The house is less than 10 years old and the joists are 16ft long before the beam.

Will this be enough to safely support 2500-3000 lbs? The tank weighs 2500 plus people.


  • 2
    this is the point where you talk to a structural engineer and don't trust random people on the internet with the integrity of your residence May 11, 2021 at 15:53
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    Your sketch implies a relatively small footprint for the tank, which makes for a very high "pounds per square foot" (or newtons per square meter) loading, far beyond what your house was built to for normal loadings for code. Hire the engineer. If you insist on not hiring the engineer to tell you exactly what to do where to get it right, you'll want to add some beams and columns under the tank area. The advantage of using an engineer is you can get those exactly right, rather than guessing what you need and hoping it works. Also: are you in a seismic hazard zone?
    – Ecnerwal
    May 11, 2021 at 16:18
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    How many people are you putting in your fish tank?
    – FreeMan
    May 11, 2021 at 16:20
  • 1
    The usual pattern is one hapless associate for effect, followed by Mr. (or Ms. we hear) Bond and leaving the house in time for Mr. or Ms. Bond to escape from whatever people eating thing lives in the tank, I believe, rather than sticking around long enough to be sure. Be sure to pet the cat.
    – Ecnerwal
    May 11, 2021 at 16:29
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    If 5' across the joists the 5x16x40lbs per sf = 3200 lbs total for that 80 sf. and you're dealing with a concentrated load. You are definitely in the range of needing an real engineer to look at actual conditions to verify no structural flaws are present. May 11, 2021 at 18:59


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