Floor Joists vs Ceiling Joists in Apartment

[John08007]

Hmmm... then a 150 lb person standing with feet together would also be 4x the design capacity

I thought same thing, maybe it for the entire floor. So, a 10x10 room can support 4000lbs 10x10=100×40=4000lbs

 

[Reefahholic]

I ever did this my wife would literally kill me. Hahahahahaah

It’s only tape.

 

[dennis romano]

Been following the thread. Many years ago, I had a 29 gallon tank in my apartment which was on the second floor. My downstairs neighbor was banging on my door at 3a.m. The tank blew a seam and the water was coming through her ceiling. Imagine if one of your hose connections blew.

 

[Soren]

Hmmm... then a 150 lb person standing with feet together would also be 4x the design capacity

I thought same thing, maybe it for the entire floor. So, a 10x10 room can support 4000lbs 10x10=100×40=4000lbs

The loading limits have to do with safety factors and load distribution (which is considered somewhat with pounds per square foot). Note differences between point loads (similar to the example of a person standing with feet together) and distributed loads (such as a well-supported aquarium). A quick Google search brings up many results explaining this, such as "Understanding Loads and Using Span Tables" or "How Much Weight Can A Floor Support?".

Normally, the rated limit will be a fraction of the actual limit to add a factor of safety to prevent failure. This means that someone reading a limit of 40 pounds per square foot that may push the bounds and actually apply 50 pounds per square foot will not actually cause the floor to fail but will be cutting into the factor of safety. This also means that a mostly static load like an aquarium will reduce the allowable live load of the floor, since this weight will add some stress to the joists from the aquarium until they are supported. If there was no factor of safety, failures would be very common from issues such as assuming the total weight of a reef as though it were full of saltwater only. Adding rock would increase the weight and cause it to exceed the true point of failure if the weight of the system was not limited under that failure point by a factor of safety.

It is also very important to consider how close to the wall the aquarium sits. Technically, the strength of the joist has more to do with moment (weight times distance) than it does with just weight. The further from the support you move the weight, the greater the moment and the higher the stresses on the structure. Essentially, placing an aquarium next to a wall drastically limits moment by reducing the distance from support to be only the front-to-back width of the aquarium. This allows for much higher allowable weights than if it were in the center of the room.

Also note that damage can still occur even if the joist itself does not fail. As the joist sags, it will stress attached items, such as the floor boards on top being compressed and the drywall ceiling beneath being stretched. These can be cracked from the stresses even if the joist does not break.

 

[Dub]

Yeah that’s what I’m thinking.

Don’t believe the direction of the joist makes that much difference unless you are placing aquarium against the wall the joist is resting on then they would hold more weight as mentioned before. If the joists are week enough to allow the aquarium to lean away from the wall they are very week and you would feel spongy as you walk in the area. The likely reason for the lean is the tack strip holding the carpet against the wall. It is another 1 inch wide and has nails sticking out of it to grasp the carpet. Try moving aquarium 1.5 inchs from wall. All said though large aquariums in apartments is very risky. I would worry about anything over 500#

 

[Reefahholic]

Don’t believe the direction of the joist makes that much difference unless you are placing aquarium against the wall the joist is resting on then they would hold more weight as mentioned before. If the joists are week enough to allow the aquarium to lean away from the wall they are very week and you would feel spongy as you walk in the area. The likely reason for the lean is the tack strip holding the carpet against the wall. It is another 1 inch wide and has nails sticking out of it to grasp the carpet. Try moving aquarium 1.5 inchs from wall. All said though large aquariums in apartments is very risky. I would worry about anything over 500#

Thx man!

 

[Soren]

Don’t believe the direction of the joist makes that much difference unless you are placing aquarium against the wall the joist is resting on then they would hold more weight as mentioned before. If the joists are week enough to allow the aquarium to lean away from the wall they are very week and you would feel spongy as you walk in the area. The likely reason for the lean is the tack strip holding the carpet against the wall. It is another 1 inch wide and has nails sticking out of it to grasp the carpet. Try moving aquarium 1.5 inchs from wall. All said though large aquariums in apartments is very risky. I would worry about anything over 500#

The direction of the joist could make a large difference. In the case where the joists run parallel to the short side of the aquarium, load will be distributed over more joists which will provide more support. In the case where the joists run parallel to the long side of the aquarium, the load will not span over as many joists with more load on each spanned joist.
Say the joists are spaced 18" apart (not typical, but makes math easier) and you want to have a 18"X36" aquarium. If the joists run parallel to the long side, the aquarium would either have the front and back resting on a joist each or there would only be one joist supporting the aquarium with the front and back being supported by the floor spanning between the joists. If the joists were running parallel to the short side, the minimum number of supporting joists would be 2 while you could have the center and both ends of the aquarium stand supported by a joist if positioned perfectly. Of course, this has less effect when you are close to the wall, since the wall will end up taking most of the load due to lower moments.

 

[Soren]

Thx man!

The direction of the joists could have a significant impact for a long tank! Be careful with this, even though it may matter much less in your specific arrangement due to close walls on three sides.

If the joists are running parallel to the back wall with the window, you will have significant support from all three walls around the tank (assuming the walls are supported by the same wall arrangement right below).

If the joists run parallel to the side walls, the tank will be supported only by the back wall and the joists will not be supported until they reach the wall behind where you stood to take the picture. The longer span will reduce the ability to support weight.

 

[Reefahholic]

Hate to be the buzz kill but make sure you check your lease. We aren't allowed to have tanks here and can be evicted if we are caught with them (glad I am finally moving). Also, even if we were we are required to keep the windows clear of furniture/permanent obstructions due to egress rules. They've moved my stuff before b/c they thought it was blocking it.

If you don't want to tell the management about it and maintenance comes in and finds it they sure are.

Where did you find this on the lease. I don’t see anything about it.

 

[infinite0180]

You could also consider more of a frag type system... a shallow 4x2 tank would be considerably less weight. Maybe something only 1 foot deep... before i bought my house this year i had a nano because i was in an upstairs apartment and my landlord was a jerk... i was too paraniod!

 

[Kellie in CA]

Where did you find this on the lease. I don’t see anything about it.

Is there a no pet policy? It will typically fall under that. I always have my tank written into the lease so that there is no problem later. This restricts me to small tanks, but better that than nothing, I guess. I have my tank on the ground floor now, but my biggest worry was always my tank breaking and flooding the downstairs neighbors home. Even worse, it crashing through the floor on top of someone... Yikes!

 

[Reefahholic]

Is there a no pet policy? It will typically fall under that. I always have my tank written into the lease so that there is no problem later. This restricts me to small tanks, but better that than nothing, I guess. I have my tank on the ground floor now, but my biggest worry was always my tank breaking and flooding the downstairs neighbors home. Even worse, it crashing through the floor on top of someone... Yikes!

I didn’t see it by the pet addendum.

 

[Coinzmans Reef]

The joists should be perpendicular to the length of your tank. The tank needs to catch as many joist as possible. I put a 120 on my second floor however I had a custom stand built out of angle iron. Instead of load pointing the floor in the four corners the angle spread the load across the entire length of the tank. The stand was built like a regular stand but the bottom matched the top flat no legs You would not put a tank on an upside down stand, the four legs would punch thru from the weight of the tank same with a floor.
The closer to the wall the better there is less chance of floor joists warping from weight. Imagine standing on a 2x4 along the wall edge no deflection however go to the middle and your in trouble.

 

[Dub]

The direction of the joist could make a large difference. In the case where the joists run parallel to the short side of the aquarium, load will be distributed over more joists which will provide more support. In the case where the joists run parallel to the long side of the aquarium, the load will not span over as many joists with more load on each spanned joist.
Say the joists are spaced 18" apart (not typical, but makes math easier) and you want to have a 18"X36" aquarium. If the joists run parallel to the long side, the aquarium would either have the front and back resting on a joist each or there would only be one joist supporting the aquarium with the front and back being supported by the floor spanning between the joists. If the joists were running parallel to the short side, the minimum number of supporting joists would be 2 while you could have the center and both ends of the aquarium stand supported by a joist if positioned perfectly. Of course, this has less effect when you are close to the wall, since the wall will end up taking most of the load due to lower moments.

Agreed if there were no flooring to transferr load to adjacent joists.

 

[Soren]

Agreed if there were no flooring to transferr load to adjacent joists.

I would not count much on this when considering high weight concentrations that a large reef will apply. The flooring will not provide enough support if the feet of the frame fall between joists. Another factor that needs to be considered is the type of stand. If it has individual feet, all loading will be concentrated as point loads with a need for the feet to be very near or directly over the joist.

It would probably be best to build a frame of construction lumber and plywood to level the stand base and ensure that load is distributed as evenly as possible over the footprint of the stand. This would reduce the importance of determining the direction of the joists, as the frame would essentially add joists or catch more joists. This frame could also be built all the way out to the side walls of the alcove in this particular instance to utilize support from the walls. The frame can be built to ensure that there are boards directly supporting the stand at appropriate points.

 

[Coinzmans Reef]

When ever building a stand with lumber you must use kiln dried lumber otherwise you risk warping and contraction from moisture loss. Personally I never use lumber. I have built stands with metal frame and than added pine over the frame for that cabinet look.

 

[BackToTheReef]

Where did you find this on the lease. I don’t see anything about it.

It is in my pet addendum.