Installing a hot tub in my garage. Need some advise.

[rockman6104]

Hello everyone. I'm glad I found this forum.


I'm turning my garage into a man cave for myself.


I've just purchased a used Balboa HS200VS 6 person hot tub. Ive had a Catalina Spa in the past so I have some hot tub experience. The tub is getting delivered in 1 week so I have some time to get everything set up properly.


My only concern is the slope in my garage. It's not horrible, but it slopes 2" over an 8 foot span (the length of the tub). I would like to shim it for it to be level. I was going to use pressure treated fence board.


What are your opinions/suggestions on shimming a hot tub and having a hot tub installed in a garage.


Looking forward to hearing from you.

 

[ajw22]

Good ventilation. Preventing mold, mildew, or corrosion in the space. Managing humidity.

Availability of water and drainage.

GFCI protect any electrical close to the hot tub.

 

[dsmith99]

Most standalone spas don't allow for just sticking a shim under it to level it out, it would void the warranty and probably damage the tub. The spa would need to be shimmed in multiple places, all across the width so the underside can remain fully supported. The owners manual will usually detail how the spa should be shimmed, if you are purchasing from a dealer that is also installing it they should already know how to do it right. Since you would be shimming from 2" down to nothing that will require using shims of multiple thickness.

 

[codybene]

For the hot tub be sure to find a way to deal with the moisture buildup. A vapor barrier for the walls would be needed. Fans. Exhaust fans and ceiling fans would help keep your garage comfy and again, help deal with moisture. You should also consider chlorine alternatives if you don't like the smell. Good luck with your installation!

 

[Dirk]

I had to deal with a sloping garage floor for my cabinets. I built a subfloor of 2x4s and plywood, which could be a proper support for a tub, if done adequately. Then I flipped it over, drilled holes along the 2x4s and inserted 1/2" carriage bolts, each with a washer and a nut. Flipped it back over. The bolts are adjustable legs. The washers are up against the wood, the nuts support the washer. The carriage bolt rounded head is the foot. You adjust the nuts of each of your deck's legs to achieve the proper leveling. One every two feet might be enough.

Shims can move, wiggle around, etc. You jamb one in, the one next to it becomes loose. No fun. As pointed out, you'll need a lot of them. You could glue them down, I suppose. What happens when they get wet? And 0" to 2" is a lot. but a proper deck would solve for all that. I can take pictures if you're interested in what I'm describing.

Refer to the "King of Queens" TV show for more man-cave ideas!! He had both a garage version and a basement version!! Somehow, his father-in-law and wife still managed to sneak in, though. What'daya gonna do?

 

[ajw22]

I had to deal with a sloping garage floor for my cabinets. I built a subfloor of 2x4s and plywood, which could be a proper support for a tub, if done adequately. Then I flipped it over, drilled holes along the 2x4s and inserted 1/2" carriage bolts, each with a washer and a nut. Flipped it back over. The bolts are adjustable legs. The washers are up against the wood, the nuts support the washer. The carriage bolt rounded head is the foot. You adjust the nuts of each of your deck's legs to achieve the proper leveling. One every two feet might be enough.

I dont think those bolts as legs will support the weight of a full hot tub. I would not risk it.

Does Mr. Doom and Gloom know how much a full hot tub can weigh? Granted we have not been told if the OP plans an intimate 2 person tub or an 8 person party tub?

 

[Dirk]

I dont think those bolts as legs will support the weight of a full hot tub. I would not risk it.

Does Mr. Doom and Gloom know how much a full hot tub can weigh? Granted we have not been told if the OP plans an intimate 2 person tub or an 8 person party tub?

Oh, they definitely would. You could park a car on what I'm describing. Though I might not have described it well enough... Here's mine, the OP's bolts would be much shorter. He could increase the diameter, or the number of them. I didn't engineer the thing for him, just gave him an idea to consider. They're basically a series of screw jacks, and given enough of them, they'll hold up any amount of weight.

 

[ajw22]

A filled 6 person hot tub weighs about 1000lbs empty and over 5,200 lbs full. More then many cars. Size is typically around 90”x90” or 8,100 sq inches. Going to need to make sure all those bolt legs are picking up their load.

 

[Dirk]

Just for reference, according to this source, a single 1/2" grade-2 bolt will carry 7800 lbs. Just how many elephants do you normally party with?

Sorry, you're way off on this one. It's very easy to tension this system adequately, but even one bolt could hold up a hot tub.

Proof Load Tensil Strength For Grade 2, 5, 8

 

[JoyfulNoise]

Sorry Dirk, I’m with Allen on this one. Loaded tensile strength is fine but there is also creep to consider especially since those nuts and washers are jammed up against wood. Overtime the wood is going to deform and compress. Your setup is fine for shelves (I just recently had a full garage done with shelves and my cabinet guy used plastic adjustable legs to level it out...looks great, easy to adjust and holds a heavy load....but definitely not hot tub rated).

But more to the point - doesn’t the hot tub frame itself come with some amount of adjustment in it’s legs or do they all just rest on their frames?

In general, garage hot tubs are great in theory but difficult in practice. As others have pointed out, humidity control and ventilation is going to be required or else the garage is going to turn into a sauna. You are also looking at major electrical code violations (possibly voiding any liability insurance you might have) if overhead lighting exists or electrical runs are present. Pool/Spa code has very set-in-stone requirements for setbacks of any electrical devices from a body of water as well as what needs GFCI protection. If you violate that code in your setup, then you own any liability caused by it.

Me thinks you need more than a week to consider all the ramifications here....

 

[ajw22]

Just how many elephants do you normally party with?

I don’t know you well enough yet to go into such personal details here.

even one bolt could hold up a hot tub.

Proof Load Tensil Strength For Grade 2, 5, 8

Can the surface above and below the bolt handle such a concentrated load?

I think this was a good discussion for the OP to have an idea of the issues involved.

 

[ajw22]

But more to the point - doesn’t the hot tub frame itself come with some amount of adjustment in it’s legs or do they all just rest on their frames?

Hot tubs I have had expect a level concrete pad.

 

[Dirk]

I think this was a good discussion for the OP to have an idea of the issues involved.

Absolutely. My hair-brained schemes aside, seems like this thing needs to be on a proper, level slab, just outside the door of the garage... Sounds like the humidity and odor coming off it are bigger issues than leveling it...

Hot tub and splashes and stars outside. Couch and fridge and big screen inside. As the lord intended!

 

[scdaren]

There has to be a way to do this right. Don't they install those Softubs indoors all the time? I've been in hotel rooms that had hot tubs right in them!

What about framing out some 4x4's bolted to the cement, and leveling the area with some kind of fill material? Maybe crushed rock and/or decomposed granite? Or even pour a level layer of cement into it? Doesn't need to look pretty under the hot tub.

I don't know the rules on this stuff -- but maybe any electrical issues can be dealt with by converting to GFI circuits in the immediate vicinity? My garage already has those. You'll need to work out some kind of exhaust/ventilation system as well. But that should be doable. Heck, my house even has a room INDOORS with both a bathtub and a shower spewing all kinds of humidity! They actually design fans that go right into the ceiling to dump the humidity out through the top of my house!

 

[Winnie-the-Pool]

Hot tubs I have had expect a level concrete pad.

All other issues aside... Level yes, but it doesn't need to be concrete.

 

[Dirk]

All other issues aside... Level yes, but it doesn't need to be concrete.

I've jumped ship! (Even though I know for a fact I could build a level wood platform strong enough to support a hot tub!) Because I'm with Matt's other points, and now think the leveling is the "issue aside." There's some way to install a hot tub in a man cave, no doubt, but should you? Let me guess. Comfy chairs and a couch. Area rugs. Coffee and end tables. Lamps and overhead lighting. Big flat screen TV. Extensive 7.1 sound system, speakers, amps, etc. Fridge. What else? Popcorn maker? Microwave? Space heaters. Ventilation fans. With a big, wet, splashy, smelly, foamy, steamy 8'x8' tub of water in the middle of all that?

Is this garage big enough to separate these two incompatible environments?

I'm the party pooper. I guess if the OP makes this happen, I won't be getting invited over...

 

[MinerJason]

Just for reference, according to this source, a single 1/2" grade-2 bolt will carry 7800 lbs. Just how many elephants do you normally party with?

Sorry, you're way off on this one. It's very easy to tension this system adequately, but even one bolt could hold up a hot tub.

Proof Load Tensil Strength For Grade 2, 5, 8

Steel is extraordinarily strong in tension, which is the strength you're referencing, but your design has the bolts in compression, not tension. Compressive carrying capacity of those same bolts is closer to 5,000 lbs, but that's in an ideal laboratory setting with the force being applied perfectly parallel to the bolt, and absolutely no shear stress. Due to the fact that it's the real world and there will be shear stresses involved, the weak point in your concept is actually the bolts capacity to resist moment forces (bending), which is highly dependent on the length of bolt between the washer and floor. I can easily bend a half inch bolt 90° applying only ~100 lbs of force by using a short cheater pipe (did this just last week to some 5/8" bolts). You might also be familiar with seeing a 200#lb person balancing on an empty soda can as long as they stay centered, but as soon as they wiggle a little it collapses. A 5,000 lb hot tub pushing slightly sideways on a couple of those bolts with 2" of leverage could potentially cause them fold them over.

That said, I agree that a wood platform could easily carry the load. But I'd want a lot more than a handful of 1/2" carriage bolts supporting the platform, and any carriage bolts being used as feet to be as short as practically possible.

 

[Dirk]

I realized that this would be compressive, but couldn't easily find that data. Thanks for filling in that blank. Your number was higher than I expected. My biggest concern was the threads, and even one would have been strong enough to support 5000lbs. Had I built this thing, I would have used 25 bolts (2' on center, as I stated), the longest would have had 2" of thread exposed, but the shortest no threads exposed. There is absolutely no way that would have buckled under 5000lbs, even if you managed to fit in 1600 lbs of potato-chip eatin' wild men. Friction would keep the thing from significant side-to-side movement, if any. And as I said, even if that could be proven insufficient (which it is not), moving up to 5- or 8-grade bolts, or 5/8" bolts, or even doubling the number of them (1' O/C, for a whopping added expense of about 15 bucks), even with a little slop in the wood as Matt suggested (which also wouldn't happen because of the washers), sorry guys, there's no way that would fail. Not before the fiberglass would, and certainly not before some shims would. Not... gunna... happen...

Mute point. Better to put the thing outside on a slab (IMO)...

 

[PoolguyinCT]

A hot tub is a dynamic load, just sayin..