Flag Stone Patio Fine For Spa?

[Dawill]

I have a concrete & rebar patio which was then covered with oklahoma flag stone a couple years ago. I am wondering if I could put a hot tub on it. My concern is the rock is rough so obviously there are uneven spots in the patio although it appears to be "fairly" level over the span of 7ft or so that a spa would sit on. I need to borrow a large level before I know exactly how level it is though. I had a few questions in regard to placing a hot tub on the patio.

First, is it safe to put something under the spa like a thin sheet of plywood that is the same dimensions as the hot tub? Under the 4k lbs of the hot tub I assume it would mold to the uneveness of the rock. Or could I simply put the hot tub directly on the rock? Or is there something else I could use between to the two?

Second, what is the max drop over the 7-8ft span I should verify to ensure its level? I didn't specifically mention a hot tub when I had it made, although I know its strong enough for one, I believe its probably slightly tilted to allow drainage. Whats an exceptable drop over the span of the hot tub?

I'm trying to avoid pouring another concrete pad just for the hot tub as it would encroach on where I would one day like to have a pool, although I realize it might be unavoidable.

[tylemandan]

I have a concrete & rebar patio which was then covered with oklahoma flag stone a couple years ago. I am wondering if I could put a hot tub on it. My concern is the rock is rough so obviously there are uneven spots in the patio although it appears to be "fairly" level over the span of 7ft or so that a spa would sit on. I need to borrow a large level before I know exactly how level it is though. I had a few questions in regard to placing a hot tub on the patio.

First, is it safe to put something under the spa like a thin sheet of plywood that is the same dimensions as the hot tub? Under the 4k lbs of the hot tub I assume it would mold to the uneveness of the rock. Or could I simply put the hot tub directly on the rock? Or is there something else I could use between to the two?

Second, what is the max drop over the 7-8ft span I should verify to ensure its level? I didn't specifically mention a hot tub when I had it made, although I know its strong enough for one, I believe its probably slightly tilted to allow drainage. Whats an exceptable drop over the span of the hot tub?

I'm trying to avoid pouring another concrete pad just for the hot tub as it would encroach on where I would one day like to have a pool, although I realize it might be unavoidable.

Many of the hot tubs on the market require the tub be fully supported underneath and you cant shim them at all. Doing so would void the warranty. Hot Springs make some models of spas that can be shimmed up to one inch to level them without voiding the warranty. They may be others out there but those are the ones I am familiar with. Even that may not work if your flagstone deck is too bumpy. If you have a long straight edge, check the area around your tub by placing the straight edge on the ground where the tub is going to be located. You will soon see how out of whack it is.

[Dawill]

Alright.. Thanks for the info. Looks like I'll probably just create a base for the spa next to my patio with pavers or possibly concrete if I'm feeling ambitious.

[SpaTechSince1979]

I have a concrete & rebar patio which was then covered with oklahoma flag stone a couple years ago. I am wondering if I could put a hot tub on it. My concern is the rock is rough so obviously there are uneven spots in the patio although it appears to be "fairly" level over the span of 7ft or so that a spa would sit on. I need to borrow a large level before I know exactly how level it is though. I had a few questions in regard to placing a hot tub on the patio.

First, is it safe to put something under the spa like a thin sheet of plywood that is the same dimensions as the hot tub? Under the 4k lbs of the hot tub I assume it would mold to the uneveness of the rock. Or could I simply put the hot tub directly on the rock? Or is there something else I could use between to the two?

Second, what is the max drop over the 7-8ft span I should verify to ensure its level? I didn't specifically mention a hot tub when I had it made, although I know its strong enough for one, I believe its probably slightly tilted to allow drainage. Whats an exceptable drop over the span of the hot tub?

I'm trying to avoid pouring another concrete pad just for the hot tub as it would encroach on where I would one day like to have a pool, although I realize it might be unavoidable.

[SpaTechSince1979]

Depends on the spa brand you buy and how they build them?

Where do you live? What are you considering?

[Dawill]

Depends on the spa brand you buy and how they build them?

Where do you live? What are you considering?

I live near Austin, TX and I'm getting an Artesian Grand Bahama. I spoke with the dealer he said they could create some kind of wood base for it to level it for $100-150 and it wouldn't void my warranty. I'm not too worried about the weight on the patio as I could probably park a bus there for 20 years w/o any problems. Its over 4" thick concrete w/ 1" rebar (don't ask) and has flag stone just on top of the concrete for aethstetics.

My plan is now to either build a platform myself or have the dealer's people do it. Not sure if I'm motivated enough to do it myself to save a $100.

[Dr. Spa]

You have 1" rebar in 4" thick concrete???? Expect it to crack like a checker board, along every piece of rebar. Rebar shouldn't be used in anything under 6" thick (welded wire mesh should be used). 1" rebar is for 12" thick concrete.

[Dawill]

You have 1" rebar in 4" thick concrete???? Expect it to crack like a checker board, along every piece of rebar. Rebar shouldn't be used in anything under 6" thick (welded wire mesh should be used). 1" rebar is for 12" thick concrete.

I did not pour it myself. I was told the rebar is from left over highway rebar which I believe he said was 1". Maybe I'm misquoting. How thick the concrete is I cannot say. He is somebody I trust so I'm not too worried about it.