Can my slab hold a 1,000 gal tank?

[secretweapons22]

Trying to find out if my floor will hold the new tank that I am getting.

Main display: 1000 gal

Sump: 600 gal

So that would be no more than 15,000 LB, not sure but would think my slab would have no problems with that.

Any thoughts? Ideas? Comments?

[Troutmasters02]

I have taken a few structures classes for my architecture degree so I have a little background. First, we need to know how this weight will sit on the slab. Will it be four posts or box framing or....? Second, and this is the bug-a-boo, what is the slab thickness and steel reinforcement? You need to know these things, I don't suppose you want a new basement in your house.

[secretweapons22]

Not sure on slab thickness, going to have a slab guy and struc. eng. come out and look. Not sure on the tanks measurments yet, friend out of state is the one with the tank, but that will dictate what the stand is like, the sump will not be going under the tank so i will have a super heavy duty stand built.

[R.Allard]

i have been a contractor for 20+ years and most conventional slabs are 3.5 to 4" thick
with 24 inch deep x 12 inch wide beams that run length and width and around the parimiter
of the structure and the answer is probably not. remember this will be static pressure
meaning it isnt going to move it will just be a constant pressure in that one spotand your "typical" home slab isnt designed to carry that type of weight. yes the footprint will disperse the weight but even if its a post-tension slab your asking for trouble with that kind of weight.
if it were me and i wanted to set up a tank like that i would pour a secondary slab(not attached to the house) and make it a engineered post-tension slab for that weight
range.that way you could put all the plumbing,electrical and drains in you needed.
HTH
Robert

[sharkboy]

wow...that is a huge tank!!! look forward to seeing pics!!!!

[secretweapons22]

Ha, if i get the green light from the slab/ struct eng I will, other wise Ill be pouring a slab like R. Allard suggested. But that will delay the tank build.

Tell me more bout the static slab? what is that exactly?

wanna sound like i know something when the struc eng and slab guy are here, so i can ask the right ?s you know

[secretweapons22]

Is there anyway to improve the slab on the house, in the area we want the tank?

[BIGBIRD123]

I have been a Brick Mason and Construction Superintendent for 35 yrs and have gone in and added a masonry fireplaces in existing houses. A true masonry fireplace will weigh as much or more than your tank. You can cut the slab in the house and pour a new concrete base for the tank, install footings and piers to hold the weight. Robert knows what I'm talking about. It's probably the best way to do it and get it where you want it in the house.

Steve

[R.Allard]

its not a static slab.. its static pressure and what your looking for is a post -tension slab.
they lay cables through the forms pour the concrete then go back about 5-7 days after the slab is poured and put 3500-8000 lbs pounds of pressure on the cables depending on the aplication. the thing is getting it done by an engineer. for instance when we built our house we had the slab over engineered because of the soil in the area. even with building pads on all the houses around us the conventional slabs were cracking because of all the clay in the ground. most of the new houses in houston,dallas area
youll find have post tension slabs. its kinda like building your house on a bridge.
as far as reinforcing your slab by the time you pay for them to take your house apart,
jackhammer the slab out, pour new beams and slab you may have paid for the whole room on a new slab...

[R.Allard]

yes you can have your slab reinforced and it is an option but my only concern would be the setteling. im not saying it cant be done im sure it can. but for the cost factor you may be better off having a new room added on. that way if the room does settle or god forbid
something does go wrong it dosent affect the slab of the home. and end up being a nightmare. just my 2 cents though.

[R.Allard]

fwiw a post tension slab engineered should run between 7 to 10.00 a ft. our slab on a 2500sqft house was 16k and some change and
depending on the home figure 125.00 to 250.00 a SQFT for new construction home depending on the area/house/building code changes. etc bla bla bla.
if your room is 500sqft i would figure some where in the 25k to 40k range for an addition with a bathroom.

[dustint21]

Holy crap! If you go thru with this you may have to see what R.Allard and Bigbird will charge you to do the work! LOL!

[R.Allard]

sorry i dont do construction anymore. i started working for a hospital and am currently in school to be a DMCHT (dive medicine certified hyperbaric tec ) . i do consulting work for a couple ranches and old clients on new construction,water ways and mold remediation though.

[Bill S]

Not an expert on this. But, I'd look at putting an additional slab in just for the tank. Probably be cheaper, AND it would give you a room behind it for "stuff".

[Troutmasters02]

Something that needs to be considered as well is the soil. Soil in San Antonio stinks which requires additional reinforcment. I would advise hiring a soil engineer to identify any problems with movement. I would suggest modifing the existing slab. Saw cut the existing slab and pour concrete piers with a reinforced concrete slab on top may work best. (But x-rays of the slab might be needed to know where the existing concrete beams are located) Post/Pre tension slabs would not work if the tank was in the middle of the house, and be a pain to work with at exterior walls. (how would you put tension on the rods??) Anyway if you have a good engineer things will go smoothly.

And since we're throwing experience around, I've worked in architecture firms for ten years, and my boss has thirty five years as an architect (who agreed with me).

Good luck and post lots of pictures!

[rpc]

What are the expected dimensions? It would make a considerable difference between the pressure from a 20" tall tank versus a 40" tall tank.

For some of the construction guys... when I was quoting out concrete for a basketball court, a couple of the concrete guys said that a 4" slab is rated for 3000psi loading. If that is the case, a 4" slab should be plenty for almost any design. Was I misinformed or did I misunderstand?

-richard

[Bill S]

Try googling "how much does a house weigh?". Between 80-160,000 lbs - without foundation.

[Troutmasters02]

Try googling "how much does a house weigh?". Between 80-160,000 lbs - without foundation.


But we are talking about point loads on a very small area-makes a huge difference.

Also, there is going to be lots of rocks and sand which makes a large addition to your weight. (Not sure if thats apart of your total weight listed above)

I wanted to add that if you do put in a new slab, make sure that it is not attached to the existing slab. New additions to older buildings will always have differential movement. If they're connected, the two slabs will tear themselves apart (worse case). Big expansion joints between the slabs will allow movement (movement in buildings is inevitable, it's just a matter of how you treat it).

[R.Allard]

troutmaster they arent rods they are cables that run through the slab. here is alittle info...What is a Post-Tension Slab?

The prefix post, which means "after", indicates that the foundation is tensioned after the concrete has hardened. What this means is that the cables or tendons are stressed after the concrete has been placed in the foundation.

The post-tensioning industry is a spin off of the pre-stress industry which has been around since the early 1900's. The pre-stress industry is used for bridge beam type construction like most elevated bridge structures like the Atchafalaya and Lake Ponchetrain long-span bridges. These long-span concrete pre-stressed concrete beams are used for the loads and spanning ability. This type of construction or pre-tensioning was converted to "after" construction via a plastic coating or encapsulating applied to the tendons to prevent bonding of the concrete. This coating allowed the cables to be stressed after and thus the post-tension industry was born back in the lat 1960's.

This concept of "after "construction tensioning was widely accepted in the construction industry. The high strength post-tension tendons are laid throughout the foundation in both directions running from front to back and left to right, thereby creating a network grid of reinforcement both in the footings and top slab area. The tensioning of the cables applies pressure to the concrete which when this is done, squeezes the concrete together which helps the concrete better handle cracking, tensile, flexural, shear, bending and increases the load carrying capability of the concrete.

Most post-tension structures include: Parking garages, high-rise buildings, apartments, residential houses, commercial offices, metal buildings, additions, tennis courts, and even drive-ways. wonder why they have used it for so long if it didnt work???
just my opinion...

[R.Allard]

What are the costs and benefits of post-tension?

The cost on post-tension converting depends on several factors.

1) The first and often thing overlooked is that there could be a structural reason to convert to post-tension especially if your foundation does not meet new IBC and IRC Code guidelines

2) If your foundation is not engineered, you could be in violation of the New IBC and IRC code requirements.

3) There could be structural reasons to use an engineered foundation system and without a soil investigation, minimum code conventional reinforced foundation systems should not be used.

4) Most of the soil in Louisiana and Texas is compressible and has shrink / swell characteristics with the plasticity index greater than 15. Reference USDA.gov/survey website to view soil maps of the area.

5) Cost difference depends on what a post-tension engineered foundation system is being compared to.

6) Price usually varies depending on the amount of cable per square foot, the engineering cost, travel time, labor, stressing requirements, as well as design parameters.

7) The many benefits include that the foundation is engineered and exceeds the IBC and IRC code guidelines for expansive and compressible soils with Plasticity Index greater than 15. Reference IBC and IRC Code Books for foundation design and parameters regarding soil.

8) A post-tension slab can carry more loads for often times less concrete slab thickness. Approximately a 4" slab is almost equal to a 6" slab.

9) A post-tension slab can distribute the weight better because of the cables and waffling of the foundation. By utilizing t-beam computations, the exterior loads are distributed almost 36" inches into the slab and on interior beams 74" inches where a conventional footing is only about 16" inches in distributing weight.

10) The applied tensioning of the cables puts the concrete into compression which closes cracks and strengthens the concrete in flexural and tensile forces much greater than conventional reinforcement

[secretweapons22]

Ok, little update..

The tanks measurments are unknown for now, my friend lives way up north and is the one i am getting the tank from, he has not emailed me the exact meaurements.

As for ground, I live in San Marcos, so its pretty rocky here.

The house was built in the 70s so I am going to try to dig up the plans for the house and get all the expert opinions first.

I am planing on putting the tank in a spare bedroom and cutting a whole in the wall that faces the living room. The tank will be a picture frame if you get what I mean. The entire spare bedroom will be the tank room. I might even add a few 150 gal tanks to the mix, making them mangrove lagoons.

That is if it all works out the way I hope it will. Otherwise I will have to redesign my ideas.

[Troutmasters02]

Thanks for the history lesson but what your not including is the context. Lets think outside the typical residential (new construction) and realize that any slab with post tension needs to be accessible from all sides once the concrete is poured. This solution will not work for a remodel and other options need to be considered.

Just my opinion.

[BIGBIRD123]

I'm just telling you what I would do, wold cost me about $4k and I would take experience over books anyday...Good luck with your project.

[Troutmasters02]

Please explain the cost from your experience?

[kkiel02]

Too bad you didn't do this last semester. My structures textbook had equations for this type of stuff. I know concrete has great compression strength but I would definately get someone to look at it for you. What side of ih35 are you? As the eastern side is more of a clay loam soil, but the western side is much more rocky. If you were to get dimensions and data I could run it by my professor up here. He still is in the business and if nothing else could recommend someone here in San Marcos to look at it if you want?

[PhilipB]

Im about to star a war i know but heres my.02. have an engineer look at what you are trying to do. my family has been in the contracting buissness for over 35 years and every situation is different. you cant do this over the net or over the phone im sorry. i agrre alot with both robert and steve even though i dont like post tension slabs. call me old fashioned even though im young but i prefer conventional. and as far as not tying the two slabs together i would worry about that untill an engineer says not to. unless i go visit your place and look at what you have both myself and others can only give you limited help. ill tell you this though experience will smack textbooks around all day long. I can guarantee you this though, your exesting slab will not hold that much weight. not without being modified. 31/2 to 4" at 3000psi witth probably minimum sized rebar and base that was bagged and barely compacted aint goona hold.

[Troutmasters02]

POST TENSION WONT WORK IN THE MIDDLE OF HIS HOUSE. Obviously, books outweighs experience in this case.

[alton]

On this website we have disagreed on curing ICH to Bio Balls. Now I guess we can add post tension slabs to the list. I love it.
I am puzzled Geronimo is home to the Navarro Panthers and is closer to Seguin than San Marcos?

[subsailor]

lets keep it on topic and respectful

[brewercm]

Obviously, books outweighs experience in this case.


I'm not a contractor and I didn't sleep at a Holiday Inn Express last night. But this has to be one of the silliest statements I've ever heard.
A book is only the experience of the person who wrote the book along with some research. At least I hope the person who wrote the book also has some "experience", which is not always the case.

Love you all man but just cant' stand when statements like that are made.

[Troutmasters02]

Books go through a rigorous screening and filtering process by people with more experience that all of us put together, which keeps the information factual, unlike websites I know of.

Books record successful & unsuccessful field tests in construction and engineering. What do you think the engineer is going to do with this project, look up charts in a book (surprise). The point of this thread is to keep trial and error out a remodel of this scale.

So your right, silly statements are hard to stand.

[PhilipB]

i knew i shoulda stayed out of this one but than again i never listen to myself. all i can say is go and hire a professional and reputable engineer before you crack your slab in half. as far as books being factual i dont know about that one, does that cover all books or self help books? cause i can think of quite a few books that are nothin but false lies and propaganda! and just so no one takes me serious or offensive or personal ill say this, i calculated the approximate weight of 1600 gallons on a 4" slab with 3000 psi concrete bought a ingram ready mix. according to my calculations the slab will break. i got my formula from a book at the store, the formula is as follows: take the weight of the aquarium water sand and rocks plus pumps, multiply that by 8.8 than divide the sum by 2009. Now take that number and add 189%. my trucks gear ratio is 4:56 and after that comes 789 so if all my numbers are correct the slab will break as soon as the tank is a quarter full! Come on people thats funny!

[Troutmasters02]

Books in construction and engineering have to be factual, or we're in big trouble. :)

[PhilipB]

lol i agree!

[PhilipB]

heck even my sons bob the builder books get prety darn close. shoot bobs construction sites look cleaner and more to osha's standards than mine! lol

[sampsonndelila]

Just do it, If something bad happens it will be awsome to watch. Keep a camera pointed at it for the tank for the first couple days. seriously, I think you would be ok if you split the tank and sump by some distance.

[brewercm]

I'm all for hiring someone (reputable) for a job that size. I'd hate to end up being wrong in the end because of reading any book on it's own or hiring some guy driving down the road.

Of course they use books and everything else at their disposal, so do I in my job. My point was just basically that the books don't write themselves and even they can be wrong.

[R.Allard]

your correct you cant do a post tension slab in the center of the house. i didnt say you could.my statements were to pour a exterior slab not attached to the house slab.
BTW if were gonna do the whole childish he said she said... i have more experience
than you thing. i ran this past my stepfather who started me in construction. which has
over 65 years of construction experience and has been superintendent on jobs like the glen canyon dam,remodeled several thousand homes and has overseen jobs like the runways at camp penleton airport,the runways at ontario airport and parts of the 405
freeway and has spent the last 10 years building houses here in texas.
although he didnt completely agree with me on the post tension slab. his words were it was alittle over-kill and that a conventional slab would work with the right compacted pad and a good engineer. he did say that cutting into a slab in an existing
house was in his opinion a huge mistake. his concern was that the new pour wouldnt
settle the same and cause problems with the existing foundation. his words were to never cut into existing beams. his words not mine

[Troutmasters02]

Yes, indeed he is right. Differential settlement is a problem and that is why I suggested large expansion joints between the existing slab/new slab and take x-rays of the slab to locate beams prior to cutting (as I mention a few pages ago).

The design in question requires plenty of precautions since it's in the middle of the house.

I guess this thread has now come full circle back to what I was talking about earlier.

Despite the huge sidetrack, thanks for confirming it.

[subsailor]

You would think we could see some descent "Tank builds" with all the "construction guys" here. Lets stop the he said she said throwing around titles and stick to the mans topic.

[PhilipB]

like i said you guys if you would just follow my formula you would all see that only I was completely and truly correct!

[PhilipB]

and why is it that all of us gc's are so competitive? im the best!

[Troutmasters02]

It's not childish to explain the experience behind my suggestions, thats what makes them creditable. I'm simply trying to help.

[danny]

Screw it. Just get you some butterfly hooks and hang the d@mn thing.

[PhilipB]

what size butterfly hooks? and are we sure his ceiling joists will be able to hold it? anyone here know how much weight his ceiling joist can hold?

[PhilipB]

hey trout your tank is killer! love the layout

[R.Allard]

my tank is bigger than yours... no its not...yes it is... NO its not ...YES it is...

so here we have a guy that wants our help and all we are doing is fighting on who's plan is better.... shame on us. Secretweapons22 i for one am truly sorry this turned out like this.
here is my suggestion to you.
1. go to the city hall and get a reputable contractor or the BBB. they should be listed if their licenced.
if they arent stay away from them.
2.have him get in touch with his engineers and ask the contractor to get two or three opinions on your particular job.
3. dont pay a dime till the contractor gives you a bid on a contract period.
4.do not pay more than 25% of the job up front. if they dont have operating
capitol than their probably cutting corners and you dont want them anyway.
find another contractor.
get all warranties expressed or implied on paper (black & white).
ask for references atleast 5 recent jobs and 5 that are 1 year old.

if you need any assistance on helping move that monster in or parts for the tank
im sure the people on this site would gladly help. i know i would.

once again i apologize for the childish banter and hope that you dont think ill of us.
i for one would love to see that tank set up and running... itll be like seaworld in your home . by the way did you buy your scuba gear??? your gonna need it to clean the
thing...ahhh swimmin with the fishes...
Robert

[rpc]

Just for kicks I ran some numbers...

Assuming that the tank is 120"Lx50"Wx40"H (~1000gallons), and assuming that the stand is framed out with 2x4's standing on the narrow (1.5") end...
and assuming that the stand is level and the load is evenly distributed through the rectangular frame contacting the slab...

contact area = ~500 sq. in
1600 gallons = ~15,000 lbs
so the distributed load is ~30psi

Am I overlooking anything? Even if the stand/slab contact isn't even very even and we assume that we have 1/10th of the contact area, it'll still be ~300psi.

In theory it sounds ok to me.

[Troutmasters02]

hey trout your tank is killer! love the layout

Thanks, hope this project gets off the ground too.

[Troutmasters02]

Just for kicks I ran some numbers...

Assuming that the tank is 120"Lx50"Wx40"H (~1000gallons), and assuming that the stand is framed out with 2x4's standing on the narrow (1.5") end...
and assuming that the stand is level and the load is evenly distributed through the rectangular frame contacting the slab...

contact area = ~500 sq. in
1600 gallons = ~15,000 lbs
so the distributed load is ~30psi

Am I overlooking anything? Even if the stand/slab contact isn't even very even and we assume that we have 1/10th of the contact area, it'll still be ~300psi.

In theory it sounds ok to me.

Seems to me that the loads are not evenly distributed. You will have intense point loads which creates a "punching" effect on the slab. 4"-5" 3000 psi concrete slab can not withstand these point loads. Of course thats assuming that the stand is a conventional "post and beam" type construction which is so common in our tank stands. If you were to distribute the load more evenly some how (as mentioned above), then I think it might be possible, but thats pushing things.

I was thinking about this last night and something came to mind. You may be able to pour an additional slab (with rebar) on top of the existing slab to create a platform. This will help in dealing with the loads and does not require you to cut up your foundation....Just a thought.

Hope you have an understanding wife. :)

[rpc]

I agree with you, troutmaster, that it'll be tough to get an even load distribution. But even if you had the load on 4 adjustable feet, that's about ~4000 lbs per foot. If each foot was a 4x4 beam that's ~12sq in of contact area, that's still only 333 psi. From the concrete's point of view, shouldn't this be well within it's designed strength?

[Before anyone goes off about a 4 legged stand for a 1000 gallon tank... I realize it would require more bracing to handle the 10' span of a 1000 gallon tank. I am just speaking to the allowable loads of the concrete]

So then that brings back my question... is a 4" slab really rated for 3000 psi?

-rich

[Big_Pun]

my buddy and i built a 1200 gallon plywood tank in his garage with no problems, tank is viewable in his living(wall cut out) and sits in the garage, its an old house so ide say you would be ok, no issues i know he had some contractors at his work check it out before. he never finished the thread(too busy i guess) http://www.cichlid-forum.com/phpBB/viewtopic.php?t=176192&postdays=0&postorder=asc&&start=0

[Troutmasters02]

Thats a good question and it completely depends on the mix of the concrete and site conditions. I have no idea what/who built the house, but by todays standards they were less than ideal. To much water, not enough aggregate etc will drastically reduce the strength of concrete. And lets face it, some construction workers are less than scientific about their work.

So here's an eye opener for me and maybe why I suggested an "overkill".

A typical home builder job site was under construction. After digging trenches and laying rebar he had to get an inspection. The inspector came out and looked at things and approved a perticular slab's rebar. After the inspector left, the home builder pulled the rebar out and poured the concrete. Then proceeded to place the rebar into a new slab for inspection, and so on.

I guess the point of all this is we have no idea what this person has as an existing foundation. To assume wrong would be a mess.

[rpc]

I guess the point of all this is we have no idea what this person has as an existing foundation. To assume wrong would be a mess.

This statement just about sums it up.

To the OP, my gut feeling tells me that it would be ok but it's tough to be 100% sure.

-rich

[PhilipB]

that was my point. we dont know what size rebar is in there, what the spacing is on the rebar, was it properly chaired up? how about the base maeterial? was it properly compacted or has it settled and left a void between the slab and base? as far as the concrete being 3000psi how much water and agg were mixed together? was there any accelerators or retarders used? what was the weather like when they poured? we dont know any of these things im assuming and i agree with rbc and trout. one the id like to throw out there though, and that is ive had driveways poured with 3000psi and with rebar not chicken wire crack on me when a f350 which is aboubt 9000 pounds drove across it a week later. luckily it was in an easy fix area so we didnt bother testing the concrete we just assumed it was a mixture of things. my point is concrete breaks and it doesnt always take a whole lot of weight. btw that driveway a min of 4" thick

[ballardjr2000]

just something to throw out there, I don't know this or that about building, concrete, etc. i do wires, navigation equipment, power generation for aircraft etc. anyhow what about taking a 1/4 to 1/2 piece of steel and lay that on the concrete to distribute the wieght over the entire area. OR does that just not work.

[danny]

what size butterfly hooks? and are we sure his ceiling joists will be able to hold it? anyone here know how much weight his ceiling joist can hold?

Yeah I was just kidding. :angel:

[jroescher]

Just don't miss a payment on your homeowner's policy.

[R.Allard]

is it just me?? probably....
has anyone noticed or even care that the person that started this thread hasnt posted since the beginning of the 3rd page... just food for thought!!

[PhilipB]

i was kidding also about the buterfly hooks ;)

[chark]

I think it doesn't matter that the person starting the thread has answered. It was a great read and even with the arguing back and forth it seems like everyone enjoyed the conversation.

Happy reefing! ! !

[rpc]

I agree with Chark, after the silliness it was a good discussion.

[ickarys]

I'm brand new here, so I guess this is an official introduction.

I work for an architectural firm here in SA and became curious with this discussion about a 1000 gal. tank. I pulled a slab test report from one of our current projects that's in construction and thought everyone would find the results intriguing.

This is based off a report from a geotechnical engineer taking slab samples.
At 28 days, a 12.57 sq. inch sample was loaded and reached failure (it cracked) at 61,990 lbs. The type of concrete used is rated at 4000 psi strength and is engineered for a school. So please take that into consideration as i have a feeling residential construction is not required to meet this same performance.

A 1500 gallon tank, at 8.5 lbs. per gallon (12,750 lbs.) plus another 1,000 lbs of rock and sand, (13,750 lbs. total so far) as well as dry tank weight 2,000 lbs. (prob. much less than this realistically) has a total weight of 15,750 lbs. Divide this number by a minimum of (4) 4x4 supports equals a point load of a little less than 4000 lbs. per point. On a 3000 psi rated slab, 16 sq. in. area should tolerate around 48,000 lbs. of load. If you do the math and percentages, this corresponds to the characteristics of the project I mentioned above. (3000 psi is 75% of 4000 psi; 48,000 is +/- 75% of 61,990 lbs)

So i think you're in good shape, assuming the slab is in good shape.


Anyway, hope this helps and good luck secretweapon.
Glad to be here.
Cheers.

[secretweapons22]

Sorry guys I have not written back, been doing demo at the house remodeling. 18-20 hour days done give me alot of time to chat on here, however I hav been reading with smiles on my face at the varying opinions and the thought of y'all sitting at your computers typing away muttering under your breath, I am gla I have had so many replys. Once I get the house in shape the tank ideas will beguin for now they are on hold for area months