Floor Joists vs Ceiling Joists in Apartment

[Reefahholic]

I’m building a new tank soon. My last tank was only 75/G, because I’m on the 2nd floor. Last time, I located the ceiling joists with a magnet and figured the floor joists would be running the same way. When I set up the tank and filled it with water, it was definitely leaning more to the front which makes me wonder if the joists were running in the opposite direction.

Does anybody know how to easily find them without pulling up the carpet. I have a heavy duty rare earth magnet, but the carpet, padding, and whatever else is under there is just too thick. I really don’t want to pull the carpet up, but it will probably mess it up.

Here is the location of the previous tank and I want the new tank to go here as well:

 

[j.falk]

You would definitely mess the carpet up if you try pulling it up...and good luck trying to get it back on the tack strip without the proper tools.

 

[IanK]

Typically the carpenters would lay out the joists in the same manner from floor to floor. Just curious, what does it matter where the joists are?

 

[Reefahholic]

Typically the carpenters would lay out the joists in the same manner from floor to floor. Just curious, what does it matter where the joists are?

I wanna make sure it’s supported properly.

Here’s a pic of the ceiling I just mapped out.

 

[j.falk]

The leaning could simply be a slope to your flooring...not necessarily the joists running in a different direction. If you located the joists in the floor above you then your flooring should run the same way.

 

[Weasel1960]

Are you sure the building is framed with wood? Sometimes the main frame is steel and the floors are precast concrete plank. Sub framing is then used for fastening drywall. Are you on the top floor? If so you may have a precast floor but your ceiling might be the bottom chord of The roof trusses, not ceiling joists. The slight slope might be caused by improper leveling of planks or concrete topping. I would check with building manager to verify construction details.

 

[ca1ore]

What's under the floor? Can you not check underneath? Some stud finder tools have a deep setting; never tried through carpet though.

 

[dennis romano]

I would not go larger. If the floor is sagging at 75 gallons, going larger may be a disaster in waiting. Lets say you are going to 125 gals. That is an extra 500 lbs. When a floor dips under weight, usually that means that the joists are undersized (or compromised), or that there is no support like a load bearing wall under where you want to place the tank. You never know what someone may have done to compromise structure in a previous reno, especially in an older house. I have seen instances where plumbers or HVAC guys have hacked joists to the point that they were useless.

 

[Reefahholic]

Are you sure the building is framed with wood? Sometimes the main frame is steel and the floors are precast concrete plank. Sub framing is then used for fastening drywall. Are you on the top floor? If so you may have a precast floor but your ceiling might be the bottom chord of The roof trusses, not ceiling joists. The slight slope might be caused by improper leveling of planks or concrete topping. I would check with building manager to verify construction details.

I’m on the 2nd. I’m scared to ask the manager because I don’t want them to know I have a large reef tank.

 

[Reefahholic]

What's under the floor? Can you not check underneath? Some stud finder tools have a deep setting; never tried through carpet though.

Im scared to pull the carpet up. From one corner it appears to be wood floor under the carpet.

 

[Reefahholic]

I would not go larger. If the floor is sagging at 75 gallons, going larger may be a disaster in waiting. Lets say you are going to 125 gals. That is an extra 500 lbs. When a floor dips under weight, usually that means that the joists are undersized (or compromised), or that there is no support like a load bearing wall under where you want to place the tank. You never know what someone may have done to compromise structure in a previous reno, especially in an older house. I have seen instances where plumbers or HVAC guys have hacked joists to the point that they were useless.

My old tank was leaning forward slightly about 1/2”. I’m not sure if the floor was compromised or if I barely missed a joist up front or what.

Does anybody know the spacing of joist and what most apartments use for subflooring?

I’m pretty sure I was picking up the nail from the drywall with my magnet. It could have been subflooring though too. There is more than just one metal nail in the tapped areas. My magnet senses some sort of metal clips on metal flashing on those areas too.

 

[John08007]

I wanna make sure it’s supported properly.

Here’s a pic of the ceiling I just mapped out.

Are you on the 2nd floor with another floor above you? If so I would guarantee they run the same as the ones in your ceiling. If there is no floor above you then there is. 50/50 shot they run the same

 

[John08007]

My old tank was leaning forward slightly about 1/2”. I’m not sure if the floor was compromised or if I barely missed a joist up front or what.

Does anybody know the spacing of joist and what most apartments use for subflooring?

I’m pretty sure I was picking up the nail from the drywall with my magnet. It could have been subflooring though too. There is more than just one metal nail in the tapped areas. My magnet senses some sort of metal clips on metal flashing on those areas too.

There is no set distance for floor joists. It's all how the building was engineered, a thicker joists could have more distance between joists, I would say you're looking at 12,16 or 24" center to center

 

[Reefahholic]

Are you on the 2nd floor with another floor above you? If so I would guarantee they run the same as the ones in your ceiling. If there is no floor above you then there is. 50/50 shot they run the same

Yes, I’m on 2nd floor of apartment with 3 floors total.

 

[Reefahholic]

There is no set distance for floor joists. It's all how the building was engineered, a thicker joists could have more distance between joists, I would say you're looking at 12,16 or 24" center to center

Ok, do you think this will hold a 120/G if it’s by the wall. Look at this picture.

 

[Uncle99]

Can’t you check with a stud finder?

 

[ca1ore]

Im scared to pull the carpet up. From one corner it appears to be wood floor under the carpet.

I meant can you not go down a floor. How well do you know your downstairs neighbor? You could run a stud finder on his/her ceiling and that will give you your answer.

 

[Reefahholic]

I meant can you not go down a floor. How well do you know your downstairs neighbor? You could run a stud finder on his/her ceiling and that will give you your answer.

I don’t know them at all. I wish I could do that. I hate to ask.

 

[Reefahholic]

Can’t you check with a stud finder?

I don’t think it will work well on the floor. Carpet will skew the reading I think.

 

[Weasel1960]

It is really difficult to rely only on your stud finder. Without seeing a framing plan you have no clue as to if your joists are running parallel or perpendicular to your tank.