Will my floor hold?

[ereefic]

I am planning on setting up a fish tank with a foot print of 72x24 on the first floor in a duplex. The total length and width of the stand will be on the floor, NOT just 4 points. It will be going against a garage wall. Directly under the garage wall is the foundation. There are 2x10's 16" on center spanning 12' from the foundation to a steel beam. The tank would be perpindicular to the floor joists and should sit over 5 joists. Am I going to need to reinforce the floor in the basement?

[GregH]

ereefic,

You don't say how many gallons of water the tank will hold.

[ereefic]

Whoops, thought I forgot something. Actually, the whole system there will be 96x24 and will consist of 2 tanks. One tank is 72x24 and will be 210 gallons and will way around 2500-3000 lbs. when full and the other tank will be 24x24 at 45 gallons and be around 600 lbs. I planned on putting it about 6" off the wall. So actually, it'll be sitting over 6-7 joists. Thanks.

[awesomedell]

With both tanks full you'll have 255 gals of water, at 8.3 lbs per gal, it's going to weigh in at 2116.5 lbs when full, dividing that by 16 s/f (footprint of the tank system) you come up with a bit over 132 lbs per sq ft. I don't think this will be that big of an issue provided the joists are in good shape, no big knots and definitely no cracks present in any of the joists which will be under this area. This is over a basement or crawlspace? If this is going to be a permanent fixture in the home and it's feasible, adding a structural member beneath the joists supporting the tank wouldn't be a bad idea. My .02¢ for what it's worth. :coffee:

[ereefic]

This is going to be over a basement.

What i'm thinking is taking 2-2x8x8' and sistering them together and running them the total length of the tank, right below the front of the tank, perpindicular to the floor joists and using 2 of those steel adjustable floor supports on both ends of the 2x8x8's. How does this sound?

[Joe.Carrick]

You plan sounds feasible but I have a few comments.

1. Assume that each of those supports will carry 1/2 the weight of the tanks - you really don't want to impose this load on the joists. So you will have point loads of about 1700 lbs on the basement slab. You want to spread this over an area of about 2 square feet. I would put a 16" square pier on the floor at each support. These need to be secured so that they can't move.

2. If possible, use a 4x8 with 4x4 posts instead of the adjustable floor supports. You are putting these in a basement and unless the supports are at least 3" diameter pipe you might have a potential "buckling" and structural failure. The taller the column, the more likely this kind of failure becomes. Make sure the posts are securely fastened to the piers and the beam and the beam is secured to the joists. It isn't real likely, but if one or both of the posts get knocked out you would be very unhappy.

[ereefic]

I have now decided to put 3 of those posts instead of 2. One on each end and one in the center, spreading it to 3 points instead of 2. When you say 'pier' what exactley are you referring to? I was going to put a 2x8x8 and lay it flat across the joists and nail it in to help prevent any twisting of the floor joists. I then planned on running 2-1x2's on either side of the new joist and nail that in so the new joist has nowhere to go.

[pgtek]

Hi you say duplex.
Is this a house you owned or rent?

[Joe.Carrick]

I have now decided to put 3 of those posts instead of 2. One on each end and one in the center, spreading it to 3 points instead of 2. When you say 'pier' what exactley are you referring to? I was going to put a 2x8x8 and lay it flat across the joists and nail it in to help prevent any twisting of the floor joists. I then planned on running 2-1x2's on either side of the new joist and nail that in so the new joist has nowhere to go.

A pier (in this case) is a pyramid shaped concrete block that sits on the ground - or basement floor in your case. The post then sits on top of that - usually secured with a metal post base of some kind that is embedded in the concrete pier. You shouldn't just put the posts on the top of the slab because the load would be concentrated on only a a 3-1/2" square area and could easily crack the slab.