Hot Tub on Ground Level Deck - best practices and materials?

[A.O.]

Hi all, just returning to clarify something. Am I correct in thinking that it is very important that the tub be at or above grade? The initial plan (for the hot tub sitting right on top of the deck) was to dig down 8", fill with 3-4" of crushed rock/road base, then use that as a the base for the deck framing. It seems to me that I cannot place the hot tub any lower than the base to avoid water running down on its base, correct? And so the framing would need to start at ground level rather than below? If I do that, it seems like the deck will then need to be at least 8-10" above grade, if not more, which then causes problems as stairs will eat up a lot of the deck space. Hmmm.

Pardon my ignorance -- totally new to this world!

So it sounds like you are talking about just laying your deck framing on that crushed rock base, to me that sounds like a bad idea. Your hot tub is going to weigh 2000 to 4000 pounds not including the people and I'd want a more stable platform then that. I'm sure some have gotten away with that but I wouldn't want to. Heck even when I am making a small (hot tub sized) concrete pad I'll dig a couple post holes in it somewhere maybe a food deep or so for concrete to flow into to lock it into place so it wont shift on me.

[betsbillabong]

Oh! No, that's not the plan. If going the 'building the deck around the tub" plan, I would place the hot tub on framed gravel, but still ask the contractor to pour footings.

But after spending a bunch of time on the design, I think it will be hard to implement that approach -- in order to ensure access to the entire tub, I'd need to build in removeable hatch panels/step to the design around the hot tub, leaving me almost no sitting room. I also think it would make the deck higher than I was hoping for (privacy issues, etc).

I'm currently thinking it's a better idea to just create a low floating deck that is reinforced in the hot tub area to be sure that it can carry the load. Some sources have suggested concrete deck blocks on the crushed rock/sand, but I'm thinking I should have the footings poured. It will probably be about 7" above grade. Thoughts?

[betsbillabong]

@bud16415 I missed your reply, sorry!

I was thinking I'd actually have to pour footings below the frost line. Would concrete deck blocks on the surface actually stay level? I want to be sure to do this right, without spending a fortune.

[bud16415]

Where I live up on the Great Lakes we have a frost depth of 48” plus. The blocks I used (12) for a 12’x16’ deck 32” high were these,
https://www.lowes.com/pd/Common-7-in-x-11-in-x-11-in-Actual-7-125-in-x-10-375-in-x-10-375-in-Concrete-Deck-Block/50113084?cm_mmc=shp-_-c-_-prd-_-bdm-_-google-_-lia-_-210-_-brickandblock-_-50113084-_-0&placeholder=null&ds_rl=1286981&gclid=Cj0KCQiAvP6ABhCjARIsAH37rbR7yINBeTJD2XJTXPU1iMHD5mom_3W7HsE2zfD01vkyWW40_u79qjYaAtoNEALw_wcB&gclsrc=aw.ds

I set them in the ground to the depth of the slots and in my case I went up with 4x4 posts a couple feet to my 3 beams. You could if your ground is level just set your low deck in the slots.

They are tapered and when the ground freezes they are locked in place and if the ground goes up the whole deck will float with it. mine is next to my house 1” gap so I can judge the movement and it might move ¼”. It has been in place like this for 7 years without issue. If you used paving blocks or a gravel base you would also see movement.

My deck was 100% screwed and is a strong unit that can take any small twisting like that easily. Where you get into trouble is if you use your house and a ledger for one side support and then the other end is able to move. A plus was without it attached to the house and being free standing where I live it didn’t involve permitting at that time.

I had mixed comments when I built it like that from some of my building friends and all I can tell you is it worked great for me. In fact two years ago a giant maple fell on the house and deck in the neighbors yard and the pergola over the tub and the deck rails stopped it from taking out my kitchen. I had to replace some of the above deck wood but the deck itself wasn’t moved or damaged.   

[betsbillabong]

Thanks! This is very helpful.

[A.O.]

Hey betsbillabong, what did you end up doing with this? Did you get that tub yet?

[betsbillabong]

Hi! Just seeing this. It has been REALLY hard to get contractors to actually get quotes to me. But also the tub has been delayed (surprise, surprise).

I've decided on a ground-level freestanding deck that will hold the hot tub. It will be dug down several inches and filled with crushed rock/gravel to keep drainage good and the area dry and to dissuade weeds and critters.

I'm still not clear on whether it's necessary, but I think I will likely go with concrete footings just in case, to be sure it's solid. And if/when I go to refinance, I don't want to get dinged for having a cheap deck. I don't think it will be THAT much more expensive.

I'm excited for the tub to come, but damn I am so tired of spending time on this project. I just want to soak!