Tank size and floor support question

[BlindGirlReefing]

I'm looking for a new tank and would love some input about tank size and floor support. House was built in 1932 with full basement on concrete floor. Floor joists are 2 x 8, 24 inches on center. The subfloor is 2 x 6 wood planks run on a diagonal (no plywood) and above that is 1 x 4 x 36 wood plank flooring (photo attached....apologies for the cobwebs). I'd be placing the tank against an exterior wall, perpendicular to the floor joists. How big is too big for this floor? At what point should I consider adding additional support? I'd like 180 ish gallons. I've done tons of googling but most references are to new construction. I'd rather have the input of experienced reefers anyway. Thanks in advance.

 

[Kingsley_Reef]

For reference your bathtub holds about 50-60 gallons of water and is typically placed in these locations 2x8 joists not ideal but that’s period correct I would definitely add support underneath for insurance and piece of mind But how big of a tank are you looking for???? you could always build a closet directly under the tank with the appropriate sized headers for door span and call it a win win

Easiest way 3. 2x10 sandwiched together to make a beam and add posts of floor jacks underneath be happy to draw anything up for you if needed

 

[skiergd011013]

How big of a tank?

 

[BlindGirlReefing]

I'd like 180-200 gallons if at all possible, but I'd be happy to settle with 120.

 

[skiergd011013]

I'd like 180-200 gallons if at all possible, but I'd be happy to settle with 120.

Id have a carpenter look at the spot and give you an opinion. If it was a 55 gallon or so i would have no concern. But peace of mind getting an expert opinion. Tanks are heavy, but the load is also fairly spread out.

 

[mjszos]

With all due respect to the wealth of knowledge on this forum, you don't need the opinion of reefers - you need the opinion of a structural engineer.

 

[Freenow54]

I'd like 180-200 gallons if at all possible, but I'd be happy to settle with 120.

you probably know the water alone is 10 lbs a gallon at least for me. Then add rocks equipment ...... Its an engineering question as to insurance? Who knows. I will look in an old book I have if I see anything I will input but no one wants the liability. Ask an engineering student unless you know one in the business

 

[danreef55]

With all due respect to the wealth of knowledge on this forum, you don't need the opinion of reefers - you need the opinion of a structural engineer.

Absolutely. A few hundred dollars to find out that with some support you can have 96" tank:)

 

[danreef55]

LisaMarie, consider doing a basement sump. You would love it.

 

[mjszos]

Absolutely. A few hundred dollars to find out that with some support you can have 96" tank:)

100% agree. The "it looks good from my house" level of engineering that would happen here is great and all, but if it crashes through your floor we hold no liability. If an engineer signs off on it, you may be able to hold them liable for damages.

 

[Sean Norman]

Your floor joists are too far apart and too small. Granted they are full dimensioned vs nominal lumber, but current standard would be 16 inches on center.
Diagonal sheathing is great and very strong and resistant to racking, but it has an increased number of joints. The hardwood floor over the top does add some strength but also weight.
I would concur that having a professional look at it would be good. But.. it is also easy for them to try and upsell you.
If it were my house.. I would add additional floor joists in between the existing. These would need to go from load bearing wall to load bearing wall. They could be the same width( 8 inches) but I would consider going up a size.. maybe a 4x material. I would also consider some direct post support spanning the area where the tank will sit. I would confirm the make up the concrete floor. Is it “rat proofed” where a thing layer of concrete is layer over the dirt or is it a poured slab. It would not hurt to break out a portion dig down add some concrete as a footing and then you can apply vertical posts to support the floor joists. You could also span the floor joists with a 4x material and then apply the post supports. The post supports can be 4x4 posts on pier blocks and or some of the commercial post screw jacks.
Again.. there is more that needs to be looked at.. is there a second story and load bearing. I would support getting a professional opinion.. but if they start talking crazy amounts of work.. move on to another.

 

[BlindGirlReefing]

LisaMarie, consider doing a basement sump. You would love it.

That's the plan. I just finished setting up the RODI and mixing station in the basement and the sump is in the works. Having a basement makes reefing so much more convenient. It's the first house I've ever owned with a full basement. I'll never go back!

 

[BlindGirlReefing]

Your floor joists are too far apart and too small. Granted they are full dimensioned vs nominal lumber, but current standard would be 16 inches on center.
Diagonal sheathing is great and very strong and resistant to racking, but it has an increased number of joints. The hardwood floor over the top does add some strength but also weight.
I would concur that having a professional look at it would be good. But.. it is also easy for them to try and upsell you.
If it were my house.. I would add additional floor joists in between the existing. These would need to go from load bearing wall to load bearing wall. They could be the same width( 8 inches) but I would consider going up a size.. maybe a 4x material. I would also consider some direct post support spanning the area where the tank will sit. I would confirm the make up the concrete floor. Is it “rat proofed” where a thing layer of concrete is layer over the dirt or is it a poured slab. It would not hurt to break out a portion dig down add some concrete as a footing and then you can apply vertical posts to support the floor joists. You could also span the floor joists with a 4x material and then apply the post supports. The post supports can be 4x4 posts on pier blocks and or some of the commercial post screw jacks.
Again.. there is more that needs to be looked at.. is there a second story and load bearing. I would support getting a professional opinion.. but if they start talking crazy amounts of work.. move on to another.

I didn't even think about the concrete floor. I verified that it is a poured slab. Thanks for pointing that out.

 

[danreef55]

That's the plan. I just finished setting up the RODI and mixing station in the basement and the sump is in the works. Having a basement makes reefing so much more convenient. It's the first house I've ever owned with a full basement. I'll never go back!

AWESOME. I wouldn't have done my build if I couldn't have a walk around sump. It sounds like it will be super so start a tank thread and we can follow along your journey. All the best

 

[BryanM]

I just set up a 220 gallon system, similar situation to yours. I shored up my floor under the house so i wouldn't worry about it in the future.

 

[Paul B]

I'd be placing the tank against an exterior wall, perpendicular to the floor joists.

I would have no problem putting that tank in that location perpendicular to those joists next to the foundation. If I had one, I may put another tank on top of that. Most of the weight is on the brick foundation wall.

I was a construction electrician in Manhattan for almost half a century and I can guaranty that location will hold a Toyota Landcruiser. But you may not get it through your door. :beaming-face-with-smiling-eyes:

I installed my wife's walk in tub in the center of those joists and installed transformers much heavier than that. I wouldn't worry about it.

If you are concerned, just get 4 other 2X8s about 6' long and bolt them or sandwich them to your existing joists.

(but if the thing falls through the floor, I didn't say it) :beaming-face-with-smiling-eyes:

 

[Marco_99]

I didn't even think about the concrete floor. I verified that it is a poured slab. Thanks for pointing that out.

My concern would be your foundation wall. My mom and dad‘s old house was brick foundation like that. They were dirt walls until my dad and I dug the whole house and put a full basement under it with 8” block and a poured slab.

That dimensional lumber is very strong compared to anything today but it’s how they put stuff together that’s sketchy. If it were my house I would go in doubling up the existing joists and I would split each cavity with a doubled joist. I might even put some 3/4 ply board inside the joist cavity and PL400 it to the bottom of the sub floor of where the tank would be located with some vertical cross blocking underneath between joists every 12inches or so, the only reason I would do that is if your tank is gonna have leveling feet I don’t really like the pressure points, but it is functional. That old subflooring like said above has lots of joints. It’s basically put down like lathe lol. On each end of the room, I would probably put two jacks or use 4x4”s or 3- 2x4”s glued/screwed together to support each end of a makeshift 2x6 beam a foot or two out past the tank length.( I say this with a makeshift beam and some kind of poles or jacks because I can’t see what your foundation is to the floor or what the other end of the joists are resting on) if you have a good foundation wall supporting your sill plate or a good supporting wall on the other side I probably would pass on the beam/jacks.

If your basement is gonna be unfinished and the room underneath doesn’t matter I would just take these measures about 2 foot out from where the tank would be. If you want it open under there then the joists have to run from the outside sill plate to some sort of a load-bearing wall or beam/jacks. I don’t know what’s on the other side, but you’d have to run them full length if you want it open without two more supports in the way, all kind of confusing I know, but if I was putting a 200 gal tank up top, this is what I would do if it was my house lol. When you tear into these older houses you can find some pretty interesting (sketchy) engineering.

I mean, it’s probably a bit overboard but at minimum, I would double the joists and split the cavity with adding two more joists w/out jacks if there’s good foundation under what I can see and there’s a nice load-bearing wall or another sill plate supported by a good foundation. Me personally with it being 24oc with 2x8’s and that sub flooring hard no would I put 2,000 + lbs.

I have a 120 gallon tank in my upstairs I have 2 x 8 joist with an unfinished room underneath and I doubled all my joists from outside sill to the interior 2x12” lvl beam and they’re on 16 0C

 

[Marco_99]

I would have no problem putting that tank in that location perpendicular to those joists next to the foundation. If I had one, I may put another tank on top of that. Most of the weight is on the brick foundation wall.

I was a construction electrician in Manhattan for almost half a century and I can guaranty that location will hold a Toyota Landcruiser. But you may not get it through your door. :beaming-face-with-smiling-eyes:

I installed my wife's walk in tub in the center of those joists and installed transformers much heavier than that. I wouldn't worry about it.

If you are concerned, just get 4 other 2X8s about 6' long and bolt them or sandwich them to your existing joists.

(but if the thing falls through the floor, I didn't say it) :beaming-face-with-smiling-eyes:

Bolting 6 foot chunks of 2x8”s to the existing joists is probably going to do nothing. The sister joist needs full end to end support to be effective at keeping deflection and load bearing properties. If anything bolting half a piece onto an existing joist would probably just compromise it more than help it. But I am not an engineer so take that for what it’s worth lol.

 

[Blue Collar Reefer]

I specialize in framing, and I am a licensed GC. The common span tables used for residential figure 10psf or 20psf dead load. Using a 20psf dead load 2x8 24oc can span 9’5” per todays code. (Assuming lumber species is SPF #2) If your current joist span were the max 9’ 5” with a 6’ tank (perpendicular to the joists) they could handle a dead load of approximately 1,140lbs
I’m actually in the process of putting a 180 in a room in my house with 2x8 joists. I am going to put a double 2x12 beam under ~6 ft span perpendicular to the joists posted down.
Or you could sister the joists under the tank with LVL, assuming you can get proper bearing on each end. The 2x6 subfloor will also help, but I would recommend additional support before putting a 180 on your floor.
Just a couple options.
Hope this helps.

 

[Paul B]

Bolting 6 foot chunks of 2x8”s to the existing joists is probably going to do nothing. T

I have to disagree a little. If those joists were to break which is unlikely, they would break under the tank probably 18" or so from the brick wall. Thats what the sandwiched joists are for. I built a bump out of 6" in my last house and thats what I did and what the building inspector had me do.

I also did it many times as a construction foreman. Of course running new joists all the way to the center beam is better but IMO not needed in that situation.

But as was said above, if the tank is on legs, I would make sure the legs fall on a joist or build cross joists in between the structural joists where the legs go.

But I would still park a Toyota Landcruiser on the floor just as it is. I don't buy foreign cars so I would use a GMC truck :beaming-face-with-smiling-eyes: