Need help with floor joist assessment prior to any tank upgrade

[matt]

Ok, looking for a little help. Anyone got structural engineering skills?

 

I currently have a 46 bow (3 ft) on my main floor that runs perpendicular to my floor joists and on top of 3/4 ply subfloor. The current tank spans aleast a couple joists and is on an exterior load bearing wall. I'm wondering how much bigger I could safely go.

 

This is in a 2 level townhouse + basement, so the joists run from one of the side walls of the unit to the other side wall. Except, there are u-turn stairs (lack of better word) between each floor with a landing. On each side of the stairs (or at least the one side I can see) there are double joists.

 

As you can see further below, these are truss joists rather than a i-beam or a solidy 2x10 kind of deal.

 

Sooooo, what kind of load do you think these joists could handle? My wife suggested a spot for a new tank that would make it run parallel to the joists and along a wall shared by the stairs. I need to get a rough idea of what size tank could safely run either parallel or perpendicular to my floor joists.

 

Any advice or thoughts on this?

 

I'd prefer not to pay a structural engineer as I'm not going to put a 300g or anything on this level....but I would like to go bigger than 46...maybe 75, 120, 125 or even 180 if I could actually swing it. I shop used, so it's tough making quick decisions when I'm afraid my floor can't handle my big tank dreams. And yes, I could put a tank in the basement...but then I won't get to see it very often and that's not the goal.

 

For reference, this is a shot of a double joist by the stairs.

 

[gmerek2]

I went with a 125g on load bearing Ibeam. Perpendicular to joists and it helps that it is 72" long to cover more joists. I also ran sump to basement to help with space and weight. no problems but it does make me nervous when I have people over.

[matt]

I went with a 125g on load bearing Ibeam. Perpendicular to joists and it helps that it is 72" long to cover more joists. I also ran sump to basement to help with space and weight. no problems but it does make me nervous when I have people over.

 

Thanks! ...and yeah, I thought about getting a 125g and running in about the same spot as the current tank. It would catch several joists that way. It's just that I'd really like a 24" depth tank...like a 120...or a 105 dsa (haha, like I'll find one). And then there is my wife suggesting a put a bigger tank (yep, she said bigger) in another spot that would be parallel to the joists. Still a 75 or 125 in roughly the same spot may be the way to go.

 

Anyone else have some experience to offer here?

[Jason Rhoads]

Not sure about the structural stuff, but I am in the process of moving to a place in Lake Ridge, and will have to have you over sometime! I am on Foothill St. (off Mohican, near Lake Ridge Middle School).  

[six-line]

I'm working on setting up a 225 on the main level (basement under) of my home I have it spanding 4 floor joist perpendicular on the main beam of the house. I also added a 4"x6"x8' beam held up by two new loly columns. The tank is about half full so far I'll tell you how it all works out after this weekend.

[surf&turf]

You should be fine with anything up to a 125 sitting on new construction. I had it explained to me from a contractor as "not any different than having 3 or 4 of your biggest friends sitting on your sofa. "

[zygote2k]

If you jump up and down, does the current tank move? Joists may be able to physically hold it, but construction techniques may not allow for full loading without tank vibrations. I've seen it in many new houses.

Edited March 1, 2014 by zygote2k

[six-line]

I get some tank vibration now, what's the best way to get rid of them?

[dipg]

We have similar truss joints in our 4 level townhouse. We hired a structural engineer as I am planning on upgrading my current tank to a approx. 250g tank. The tank is going to sit perpendicular to the joists on 2nd level parallel to load bearing wall. and the estimate for our tank was going to be approx. 3000 lbs and the structural engineer gave an OK.

I was surprised as we have slight vibration with current tank. We are now thinking of going for a smaller tank like 180-200. So with your future tank the only concern I would have is that you are going parallel to the joist. I will follow this post to see what you find out.

[dave w]

Your picture shows a truss joist.  Does this joist run wall to wall, or does it run into a header?  The header is a double joist that boxes out the opening for your stairs to go through the floor.  It has less strength running into a header than over to a bearing wall, but it would be attached with a U bracket which is very strong.

 

Generally, new construction houses have floors rated for 30 pounds dead load and 10 pounds live load per square foot, as I recall.  My memory is less than perfect.  That's 40 pounds per square foot and if your townhouse is 22' wide by 40' long that's 880 square feet and about 35,000 pounds, which would be seven Cadillacs.  If you bought a used 200 gallon tank it would probably weigh about 2000 pounds with rock and everything.   So your joists would fail if you put about eighteen such tanks on one floor of your house.

 

Furthermore, the load ratings are minimum, which means that is what your floor must hold at the center point, farthest from any bearing wall or post.  I doubt your tank will be in the middle of the floor, you describe it as being very close to a wall.

 

Jump up and down where your tank will be or where your current tank is and see if there are ripples in the surface of the water.  Even though a floor may support 40 pounds per square foot, some floors are more flexible than others and they are still within the building code minimum requirements.

 

Generally speaking, truss joists like you have are very strong joists and they are placed 24" on center.

 

Hope that helps.  Please don't waste your money on a structural engineer.  They are nice people but you could stock half your tank for the fee they charge on a house that was already spec'd and approved by the County reviewers.

[dave w]

Forgive me if the 7 Cadillacs sounds sarcastic.  Every few months someone asks if their 35,000 pound floor can support a 2,000 tank and it seems like I give the same answer.  

 

Put your tank where you want it and fill it with fresh water, then jump up and down to see if there are any ripples.  In the middle of the floor you will probably see some ripples, but near a header or a wall you should not.

 

Hope that helps.

[matt]

Thanks guys! I'm going to us e to re-read all this when I'm not half asleep.

 

I get some water movement on my current tank when I jump up and down in front of it...I do know that. And the joists run wall to wall. I think they simply doubled up on each side of the stairwell as the joists run parallel to the stairs....as pictured

 

Yeah, can't afford a structural engineer and a tank...haha...you're right on that

[matt]

Not sure about the structural stuff, but I am in the process of moving to a place in Lake Ridge, and will have to have you over sometime! I am on Foothill St. (off Mohican, near Lake Ridge Middle School).

 

Absolutely, Jason...we'll have to meet up

[howaboutme]

Structure is meant to flex. As an example, when you walk on a bridge or a parking garage, does it shake when a car drive by? If a structure does not flex, it will fail much faster than if it is 100% stiff.

[smallreef]

Not sure about the structural stuff, but I am in the process of moving to a place in Lake Ridge, and will have to have you over sometime! (off Mohican, near Lake Ridge Middle School).

 

Absolutely, Jason...we'll have to meet up

Yeah,, y'all are about 7 minutes apart (that's with that crazy roadwork on old bridge,lol)

[YHSublime]

We have similar truss joints in our 4 level townhouse. We hired a structural engineer as I am planning on upgrading my current tank to a approx. 250g tank. The tank is going to sit perpendicular to the joists on 2nd level parallel to load bearing wall. and the estimate for our tank was going to be approx. 3000 lbs and the structural engineer gave an OK.

I was surprised as we have slight vibration with current tank. We are now thinking of going for a smaller tank like 180-200. So with your future tank the only concern I would have is that you are going parallel to the joist. I will follow this post to see what you find out.

 

Dip, your tank keeps getting bigger, I love it!

 

Not sure about the structural stuff, but I am in the process of moving to a place in Lake Ridge, and will have to have you over sometime! I am on Foothill St. (off Mohican, near Lake Ridge Middle School).  

 

Jason, you're moving too far, I thought you were closer!

[s2nhle]

Your picture shows a truss joist.  Does this joist run wall to wall, or does it run into a header?  The header is a double joist that boxes out the opening for your stairs to go through the floor.  It has less strength running into a header than over to a bearing wall, but it would be attached with a U bracket which is very strong.

 

Generally, new construction houses have floors rated for 30 pounds dead load and 10 pounds live load per square foot, as I recall.  My memory is less than perfect.  That's 40 pounds per square foot and if your townhouse is 22' wide by 40' long that's 880 square feet and about 35,000 pounds, which would be seven Cadillacs.  If you bought a used 200 gallon tank it would probably weigh about 2000 pounds with rock and everything.   So your joists would fail if you put about eighteen such tanks on one floor of your house.

 

Furthermore, the load ratings are minimum, which means that is what your floor must hold at the center point, farthest from any bearing wall or post.  I doubt your tank will be in the middle of the floor, you describe it as being very close to a wall.

 

Jump up and down where your tank will be or where your current tank is and see if there are ripples in the surface of the water.  Even though a floor may support 40 pounds per square foot, some floors are more flexible than others and they are still within the building code minimum requirements.

 

Generally speaking, truss joists like you have are very strong joists and they are placed 24" on center.

 

Hope that helps.  Please don't waste your money on a structural engineer.  They are nice people but you could stock half your tank for the fee they charge on a house that was already spec'd and approved by the County reviewers.

Thank you for sharing your knowledge. i have learned alot from this.

[Jim Mc]

What is the span of your joists?

 

For example if they are only spanning 3ft then they can carry a much stronger load than if they are spanning 16ft. 

 

I have a 150 sitting on the second floor of a townhome with 2x10 joists over a 3ft span and I would consider that pushing it.  I am very sure had I put the tank say along the room wall where the joists span about 16ft it would not have held in the long term.

 

Jumping will only test if your tank will immediately fall through the floor it wont do much to see if it will hold over time.

 

While the 40psf is uniform safe load the 7 cars thing assumes they are spread evenly over your entire floor.  stack those 7 cars and I assure you the floor will collapse.

 

In any event if your worried about the load just add some sister joists and it will increase the load capacity.

Edited March 1, 2014 by Jim Mc

[dave w]

Honestly, you have nothing to worry about from 2,000 pounds of tank.  Truss joists are designed to be set on 24" centers and to span that distance between them they must be covered in 3/4" plywood.  If the builder used construction adhesive on the plywood (and 99% of them do), then the 3/4" plywood on top turns the joist into a T beam and greatly increases it's carrying capacity.  The top micron of a beam is in compression and the bottom micron of a beam is in tension.  The plywood subfloor turned that top micron of the wood beam from being 3.5" wide into being 24" wide and probably increased its strength by 30-40%.  

 

You will have no worries putting your tank on the side of your stairs.  

[gmerek2]

What about long term problems? Sure its no different than large men sitting on a couch but thats for an hour and if they are lazy up to 5 hours, but what about floor sagging and long term problems? Remember the earth quake what if there is a slightly worse one? Truss protects great down gravity force but side to side ok? Will I be worried if 5 people walk in the room and look at the tank together? If there is ever a fire possibly weakening joists please let the dispacher or fireman know that there is a huge fish tank upstairs.

[matt]

This is great help guys, really appreciate it.

 

Dave asked for a sketch...gonna try to do that soon. My kids 4th birthday party was today....30 adults and 30 kids in my little townhouse. I may need a couple days to clean up and recover. We did all sorts of things as it was Angry Bird themed....even had a mini-Angry Bird bowling alley I built in a hurry.

 

I will be sure to circle back to this thread soon. I'm still thinking about a 120/105 (48x24) or a 125 (72x18). I could used it to hold my stuff while we reno and then move the whole thing upstairs again. If anyone sees a really really good deal let me know...but I AM cheap...haha.

[gmerek2]

[gmerek2]

I have a 125 over the basement so I dont want to scare you away from anything. But I do worry when I have people over or if my wife has a few friends over doing jumping jacks with fitness videos etc. Im considering strengthening my joists and adding a supports, just for peace of mind.

[matt]

I have a 125 over the basement so I dont want to scare you away from anything. But I do worry when I have people over or if my wife has a few friends over doing jumping jacks with fitness videos etc. Im considering strengthening my joists and adding a supports, just for peace of mind.

Haha, no worries...I'm not scared yet...just want to be smart...sounds like you do too. By the way, nice score on your coral haul.

[gmerek2]

Haha, no worries...I'm not scared yet...just want to be smart...sounds like you do too. By the way, nice score on your coral haul.

haha I remember tip toeing past my tank the first time it was filled. Glad to see you are being smart and not getting carried away with the good news. thank you sir. I have missed out on so many deals on here just got lucky on this one!