A Question of Floor Joists

[Alaeriel]

Hello! Hopefully this is the right forum for this, since it applies specifically to large and monster tanks. I am not a carpenter, nor do I know much about the grading of wood or the solidity of different species. I would like to put a 200 gallon tank in the living room of a basemented house (renting, currently, so this is for a hypothetical house next year). What is the best method to ensure that in 15 years, the tank doesn't end up in the basement? I've read helpful articles that suggest sistering the joists or adding a jack, but what am I actually looking for in this new house to keep the fish and coral (and my floor!) as safe as possible? ~3500 pounds is rather a lot to ask in a 6' x 2' space. To clarify; we don't actually have a house at the moment, so I'm looking for either what specifically to look for in a new place or what to do to strengthen a questionable floor (or both!).

As an aside, positioning of the tank perpendicular across several joists against a load-bearing wall is the plan, I'm just looking for the information on the actual floor itself.

 

[this is me]

Try to look or build the house with steel beams.

 

[Millwright]

Honestly this question is theoretically impossible to answer until you buy your house. But let’s say we use the minimum building code requirements. Minimum rating for a non sleeping area is 40 lbs of live load PSF. Your tank is a live load. Let's say you tank is 2’ wide and weighs 1,000 pounds,. If your floor joists span a typical 12’ span. 12’ is a fairly good average. The 2’• 12’ section of floor was designed to safely carry a live load of 2 • 12 • 40 PSF. So 960pounds. You are over the capacity of the floor. Now if is placed in the room 90° to the above example you would be able to cary a load of 2800lbs if the tank was 6’ long. Technically speaking the orientation of your tank as far as parallel or perpendicular to your floor joist doesn’t matter because of other objects in the room. Basically turning the tank perpendicular to the floor Joists does increase the capacity. But furniture and everything else including people count towards the total live load the floor can handle.
Now that is the minimum. Depending on the local code, the spacing, span, species and grade the PSF may increase.
Now let’s say your tank did weigh the 960 lbs allowed. You could expect a deflection ip yo approximately 3/8 of an inch. That is the maximum allowable deflection.
Now let’s say said floor when you look at it is made out of 2X8’s on 16” centers. More than likely you will not be able to sister anything more than a 2X8 onto the existing 2X8’s. Therefor will still end up short of your maximum PSF needed.
At this point you will either have to add a steel beam, build a load bearing wall or add jack posts.
Personally I would build load bearing walls below the tank and place your sump in the new fish room you created in the basement.

 

[Alaeriel]

Honestly this question is theoretically impossible to answer until you buy your house. But let’s say we use the minimum building code requirements. Minimum rating for a non sleeping area is 40 lbs of live load PSF. Your tank is a live load. Let's say you tank is 2’ wide and weighs 1,000 pounds,. If your floor joists span a typical 12’ span. 12’ is a fairly good average. The 2’• 12’ section of floor was designed to safely carry a live load of 2 • 12 • 40 PSF. So 960pounds. You are over the capacity of the floor. Now if is placed in the room 90° to the above example you would be able to cary a load of 2800lbs if the tank was 6’ long. Technically speaking the orientation of your tank as far as parallel or perpendicular to your floor joist doesn’t matter because of other objects in the room. Basically turning the tank perpendicular to the floor Joists does increase the capacity. But furniture and everything else including people count towards the total live load the floor can handle.
Now that is the minimum. Depending on the local code, the spacing, span, species and grade the PSF may increase.
Now let’s say your tank did weigh the 960 lbs allowed. You could expect a deflection ip yo approximately 3/8 of an inch. That is the maximum allowable deflection.
Now let’s say said floor when you look at it is made out of 2X8’s on 16” centers. More than likely you will not be able to sister anything more than a 2X8 onto the existing 2X8’s. Therefor will still end up short of your maximum PSF needed.
At this point you will either have to add a steel beam, build a load bearing wall or add jack posts.
Personally I would build load bearing walls below the tank and place your sump in the new fish room you created in the basement.

Thank you for the reply! Side question here, is there any benefit of plumbing the sump into the basement rather than having it under the tank itself? I hadn't thought of building a load-bearing wall at all, so that's another option on the table!

 

[Millwright]

Thank you for the reply! Side question here, is there any benefit of plumbing the sump into the basement rather than having it under the tank itself? I hadn't thought of building a load-bearing wall at all, so that's another option on the table!

Currently I live in a split level. My reef tank is in the lower level family room that is a slab floor. My previous reef tank was on the first floor with a basement below it. My sump was in the basement. Personally I prefer this arrangement. I had a drain set up for water changes and all I had to do was open a ball valve and it went right down the drain. Not to mention I had plenty of room for salt water and rodi water.
Benefits I can think of less noise, larger area to work in and do maintenance, less worry about water being spilled on the floor, with a large enough sump the cool basement can help maintained a cool town in the summer and Storage for any and all equipment and supplies related to your reef tank within arms reach and not spread throughout the house.
Sorry for the run-on sentence using talk to text.

 

[jeffrey750750]

I just saw the those floor Jack's at lowes for only 65 dollars each. Not a bad investment

 

[Fish man]

Hello! Hopefully this is the right forum for this, since it applies specifically to large and monster tanks. I am not a carpenter, nor do I know much about the grading of wood or the solidity of different species. I would like to put a 200 gallon tank in the living room of a basemented house (renting, currently, so this is for a hypothetical house next year). What is the best method to ensure that in 15 years, the tank doesn't end up in the basement? I've read helpful articles that suggest sistering the joists or adding a jack, but what am I actually looking for in this new house to keep the fish and coral (and my floor!) as safe as possible? ~3500 pounds is rather a lot to ask in a 6' x 2' space. To clarify; we don't actually have a house at the moment, so I'm looking for either what specifically to look for in a new place or what to do to strengthen a questionable floor (or both!).

As an aside, positioning of the tank perpendicular across several joists against a load-bearing wall is the plan, I'm just looking for the information on the actual floor itself.

If your basement isn't finished and aesthetics aren't a concern here's what I did. My tank is only 90g but I estimated it at about 1000lbs with sump, stand, water and rock. It runs parallel to the floor joists on a span of about 16'. The tank sits over 2 joists. My basement ceiling is 10'. I bought two 12' 4x4 posts, cut 2' off the ends, made a tee and braced perpendicularly across the 2 joists under each end of the area the tank sits over. It's solid with no sag and no bounce when you walk in the room. Obviously yours would need more but it was cheaper and easier then any other solution I could come up with. This was not engineered and I don't know the load bearing capacity of a 4x4 but maybe you could do the same with 6x6

 

[Millwright]

If your basement isn't finished and aesthetics aren't a concern here's what I did. My tank is only 90g but I estimated it at about 1000lbs with sump, stand, water and rock. It runs parallel to the floor joists on a span of about 16'. The tank sits over 2 joists. My basement ceiling is 10'. I bought two 12' 4x4 posts, cut 2' off the ends, made a tee and braced perpendicularly across the 2 joists under each end of the area the tank sits over. It's solid with no sag and no bounce when you walk in the room. Obviously yours would need more but it was cheaper and easier then any other solution I could come up with. This was not engineered and I don't know the load bearing capacity of a 4x4 but maybe you could do the same with 6x6

4x4 would work for Jack posts.

Just so you know your 90 gallon is a minimum of 1300lbs plus the stand and weight of the empty sump. The weight I estimated includes 30 gallons for sump volume.