Weight vs floor

kevensquint · Dec 17, 2020

Hi guys a question that I have investigated many times over the years. But now with a new tank designed by me, on a modern type of floor that I have no idea of its strength.
Its going to be an anemone tank, 38 gallons with a small footprint 20"x24", add the wood stand 80lbs + 10 gallon sump, the tank itself is around 80-100lbs. In fact upon receiving this tank Im super happy with the way I had it made to show off my nems in a tall tank.
The floor joists are some kind of composite wood on 16".
Im sure it won't break the floor, but I dont want noticeable sag either. It will be up against a support wall. Is my floor ( pic below) normally strong enough to handle this?

Uncle99 · Dec 17, 2020

Looks like normal beams used today for residential construction to me, I don’t see any problem.
Get three friends to stand there while you have a look underneath. Do you see any stress?

I might start to get nervous beyond 120g, with no further support.

Eagle_Steve · Dec 17, 2020

Uncle99 said:
Looks like normal beams to me, I don’t see any problem.
Get three friends to stand there while you have a look underneath. Do you see any stress?

This right here. ^^^^^^^

Group hug in that spot, go look at beam. Hold level on beam before and while watching the load. For good measure, friends can bounce a little just as a double check.

kevensquint · Dec 17, 2020

The floors are floating laminate flooring on plywood with the joists under that. The "floating " flooring we walk on has a touch of give as we walk . So its actually hard to tell with people or heavy objects if the spot of sag with that kind of test is just the cushioning of the flooring or the actual floor. That said my fridge is on this floor elsewhere and doesn't seem to cause an issue. I think this tank might weigh a bit more than the fridge tho.

Max_nano · Dec 17, 2020

It looks like you have storage beneath the tank? Since you have the ability to do it, It may be worth adding support for peace of mind in case it looks like there’s any movement after attempting the group hug test.

kevensquint · Dec 17, 2020

The pic is not below the tank. Just a pic of the joists. There is no way to add support under the tank

Eagle_Steve · Dec 17, 2020

kevensquint said:
The floors are floating laminate flooring on plywood with the joists under that. The "floating " flooring we walk on has a touch of give as we walk . So its actually hard to tell with people or heavy objects if the spot of sag with that kind of test is just the cushioning of the flooring or the actual floor. That said my fridge is on this floor elsewhere and doesn't seem to cause an issue. I think this tank might weigh a bit more than the fridge tho.

Touch of give is expected with a floating floor, especially if it has a thin pad underneath it.

The group of friends standing motionless in that spot simulates the tank. The “bounce” accounts for a little extra load and to watch the beam while they do the bounce. Not a feet off the floor bounce, but a bounce with the body, so to speak.

Eagle_Steve · Dec 17, 2020

kevensquint said:
The pic is not below the tank. Just a pic of the joists. There is no way to add support under the tank

If you wanted to add support there is another way.

Depending on how you build the stand, you can spread the load out more evenly. If it is a 2x4 stand, add 2 layers of 3/4” plywood to the bottom. This will give a flat surface that will distribute the load evenly across the entire foot print. The tank would then be leveled up top and not at the floor.

Between the plywood on the stand and the plywood subfloor, you would have a thick base to take the load.

Eagle_Steve · Dec 17, 2020

Eagle_Steve said:
If you wanted to add support there is another way.

Depending on how you build the stand, you can spread the load out more evenly. If it is a 2x4 stand, add 2 layers of 3/4” plywood to the bottom. This will give a flat surface that will distribute the load evenly across the entire foot print. The tank would then be leveled up top and not at the floor.

Between the plywood on the stand and the plywood subfloor, you would have a thick base to take the load.

Forgot a part.

The plywood base just helps to get the load over more areas of the beam and subfloor, it doesn’t make the beam stronger. Basically spreads it out, so there are no main load areas like with a 2x4 stand hat has an open bottom.