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Old 01-18-2008, 12:20 PM  
theboomboomcars
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Default Strengthen floor for aquariums

I am in the process of buying a new home and want to get a 360 gallon aquarium. The Home is a 1 level on a crawl space. In addition to this aquarium we will have a 120 gallon, an 80 gallon, and a 10 gallon. We will use a 55 gallon sump with the 360. I would guess that with water, stands, rocks, etc. total weight for the aquariums would be about 7000 lbs.

I have not had a chance to get below the house too see the joists and such. I am not familiar with how the whole flooring works, though I have learned quite a bit over the last week of researching, so I don't know what to look for exactly when I do get to take a look, I am hoping that I can check it out this weekend.

I am looking for any advice on what to check while I am below the house, and then what would be some good options to reinforce the floor to hold the weight. I am planning on putting all the tanks in the same room, except maybe the 10 gallon, so I will only have to worry about reinforcing the floors for the one room.

Thank you for any help.



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Old 01-18-2008, 07:35 PM  
guyod
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Hopefully you have a high crawl space. Because your going to have to be digging some footers.

The highest my span calculator goes to is 100 psf. (pounds per square foot) so if you think your tanks will weigh 7000 lbs then 100psf would a 7X10 area.

using 100psf with 2x8 floor joists your max span is 8'6
2X10 will be 10'4

this is the distance between your main beams

Im thinking your closer to 150 psf.

My guess would put you at 6' and 8'

If your tanks are in one area you can probably get away with one more support beam directly under the tanks. Double up on 2X12 for your main beam. I like to sandwich plywood in between to help limit deflection.



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Old 01-19-2008, 05:16 AM  
CraigFL
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Quote:
Originally Posted by guyod View Post
Hopefully you have a high crawl space. Because your going to have to be digging some footers.

The highest my span calculator goes to is 100 psf. (pounds per square foot) so if you think your tanks will weigh 7000 lbs then 100psf would a 7X10 area.

using 100psf with 2x8 floor joists your max span is 8'6
2X10 will be 10'4

this is the distance between your main beams

Im thinking your closer to 150 psf.

My guess would put you at 6' and 8'

If your tanks are in one area you can probably get away with one more support beam directly under the tanks. Double up on 2X12 for your main beam. I like to sandwich plywood in between to help limit deflection.
You touched on this but my vote would be to install support columns to footers under the tanks since the load is fairly concentrated. How the columns connect to the floor joists would depend on how much room you have. If you have the room, a 8" or 10" steel beam running perpendicular to the joists supported by these column would be best.
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Old 01-19-2008, 06:52 AM  
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Well, first see what you have under your crawl space. Then think.
8.8 x 360 = 3168 lbs of water. + about 360 of gravel. + stand. If the stand is 200 lbs you still are a far cry from 7000. Your at 3728 lbs.
So take this into consideration when reinforcing the floor. You may not have to do much but you won't know until you get under to see what the construction of the floor is. "Much" is a relative term...............

JFI: I used to design and install high end reefs as well as just a few, big, almost totally sustainable fresh waters systems. This was a few years ago so I may be a bit rusty but I still remember a lot.

Now your tank. It's length is important to how the weight is distributed.
Is the tank custom made? Is it 4' long, 6' long or is it 8'?
Is your sump going to be under tank or in another room/ closet? your sump could be 40' away if need be. The water doesn't care where it flows from.
Let me leave this for now. Get back to us.

I like your idea...a BIG tank is so much easier to maintain.

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Old 01-19-2008, 09:19 AM  
theboomboomcars
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Thanks for the responses, they have been very helpful.

What should I use for support columns? 4x4s, 6x6s, something else?

Adk- I will be adding the 360 to an existing 120 and 80. I think 7000lbs may be a bit high, but better to over shoot than under. I am planning on having the sump under the tank. The tank will be 8x3x2.

The 120 is a 4x2x2 and the 80 is 4'x18"x22" (LxWxH).

Any other tips or suggestions would be appreciated.

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Old 01-19-2008, 10:16 AM  
guyod
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With out seeing your crawl space we cant tell you exactly what to do.

For support columns it depends on how much height you have.

Steel Screw jacks are the easiest thing to use. they are 2 steel poles that fit into each other. there is holes in them and you use a steel bolt through the holes to achieve your correct height then there is a big bolt up top that you screw up to get nice a snug against your beam. i think they start at 3 feet

if you need less than 3 feet then use cinder blocks to build up to your correct height. use 2 blocks side by side and alternate the seam with each coarse. you can get away with using just one chimey block put you should choke the hole up. when you get to the top you can use half blocks or bricks to get as close as you can. to be done right it should all be mortared in place. to get the main beam snug against the floor joists you can use scrap boards and shims i like to use cedar shingles because of there extra width.

i like to sit the ends on the block foundation. you will have to chip out the block to do that.

I dont see why you have to go the whole width of the house. You can probably get away with having your beam only about 2 feet longer than the fish room. if the beam is under 20 feet 3 supporting points should be fine.

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Old 01-19-2008, 10:26 AM  
guyod
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Footers should be 3 feet deep to get below the frost level but since this under your house and should not freeze at all and since this just extra support. 18'' to 24'' should be fine depending on the hardness of the ground. it should be 2 feet wide.

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Old 01-19-2008, 02:30 PM  
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I was bored and did some calculations based on craigs weight and your dimensions.

Tank----Water weight---Extras--Total---SF---pfs
360------3168----------560-----3728---24---155
120------1056----------175-----1231---8----153
80 -------704----------100------804----6----134
TOTALS------------------------5765 lb--38sf

As you can see all the tanks have very high PSF. So because of weight distribution they all weigh very close. A floor is normally build to only hold 40 to 50 PSF.

As far as craig's suggestion of columns connected directly to 1 or 2 floor joists. well I don't think he realized the tanks would span so many joists. I don't see it working.

When you look under the house inspect the floor joists for termite and dry rot very closely. . hit the joists with a hammer and listen.. A sharp loud noise is good, a thud is not.. crawl spaces have a tendency to have high humidity leading to dry rot. under normal conditions these floor joists may still have a long life but not with lbs on them.

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Old 01-19-2008, 04:48 PM  
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guyod, thanks for all the info, that will be very useful.

I went out to check the crawl space this afternoon, and there isn't a way in. I am unsure what the best way to make a way in, any tips on how to go about doing this.

Thanks for the help.

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Old 01-19-2008, 05:46 PM  
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assuming there is a couple feet of exposed cinderblock walk the entire perimater of the house looking for any place that the cinder block is replaced another material. most of the time its a painted plywood. It may even be under a porch. the openning may of been sided over.
Every once in a while they are inside. which probably means its been covered up with flooring.. but check all the closet floors, utility room. i had to cut a whole in the floor once to get in. hope fully it doesnt come to that but do not buy the house if you can't get in there first.
I noticed you from utah and im pretty sure its dry there so that means you have less of a chance of dry rot.
how old is the house?



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