# foundation for hot tub?



## SKINNY (Oct 8, 2008)

Howdy folks,

I just bought a used hot tub and need to build a foundation for it.. I know I can do concrete and am well versed in the procedure however I think it may just be a little too permanent in the event I eventually want to move it.

What I am interested in is understanding what it would take to build a gravel and or DG base for it. I plan on putting this in the corner of my lawn so I would assume I would need to dig down a bit and lay in some base material and compact it.. I am unsure of how deep to dig down and what materials to compact in.

Can someone give me some pointers on this as I have zero experience here. 

The hot tub is 6'6" sq and about 34" tall.


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## jerryh3 (Dec 10, 2007)

Before you put anything down, contact the electrician that will be doing the install. He may want to put a bonding grid underneath the tub if you are going to have it at ground level.


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## SKINNY (Oct 8, 2008)

Good advise..

Not sure if this matters but, it is a 4 wire system so 2 hot, 1 grnd, and 1 neutral.. It also must be wired to a GFCI.


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## Aggie67 (Dec 20, 2008)

Prior owner put my hot tub on PT lumber and set it on stone. And I hate him for that.

This year's big project is rebuilding the spa properly on a concrete base, redoing the skirt, plumbing, etc.

Wait, this year's project is finishing the kitchen.

No wait, this year's project is redoing the master bath.

No wait, this year's project is putting in a sink and a kegerator behind my bar.

No wait, this year's project is a yard fence.

(breathe, just breathe...)


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## SKINNY (Oct 8, 2008)

Aggie67 said:


> Prior owner put my hot tub on PT lumber and set it on stone. And I hate him for that.


May I ask what you don't like about it? 

I am definitely leaning towards concrete.. I figure it will cost me about 100 bucks in ready mix and that is about it.. I have access to all the necessary concrete tools.


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## Aggie67 (Dec 20, 2008)

SKINNY said:


> May I ask what you don't like about it?
> 
> I am definitely leaning towards concrete.. I figure it will cost me about 100 bucks in ready mix and that is about it.. I have access to all the necessary concrete tools.


It settled unevenly, and over time, the seams in the skirt separated, so there are gaps between the pieces of wood. Prior owner did a series of caulk jobs to hide the gaps, and it looks like hell. Also, the settling caused one edge of the shell to separate from the skirt a little bit. Just looks like hell, in my opinion.

For your slab, you're looking at:

38 bags (80 lb each) of concrete, at roughly $5.00 each (or $325-ish if you buy a full pallet of 40 pounders)
If you go for a delivery, they'll bang you for a cubic yard, plus delivery, and probably a charge for a short load if you're unlucky. I think you might end up paying more than $100, unless you got a quote and the dispatcher is being nice. If they sell you a yard or less, make sure it's not at the end of the day or the end of the morning - they might be trying to dump a hot mix on you. Ask for a first thing in the morning delivery.
12 pieces of 1/2" rebar, 6 ft long, $1 or so a foot
A little bit of steel baling wire, $5
Some rebar chairs for the rebair, $12 worth
3/4 ton of gravel, probably $15 a ton plus delivery
2x4's for the form $15
Some 1x2 wood for stakes for the form
misc screws for the form

Also have a decent screed on hand. Even a straight piece of wood will do, as long as it's nice and straight. And a clean straight broom, 2 wheel barrows and 2 strong backs, edge tool, and a place in your yard to dump the dregs that the concrete driver will wash off his chute. Also if the driver shows up and sees it's just you who will be wheel barrowing this stuff into your back yard, he might get ticked and bang you for demurrage.


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## SKINNY (Oct 8, 2008)

hm...

I figured the slab would be small enough to use the ready mix sacks and a mixer.. Home depot calculator says for 7x7' I'll need 30 of the 80 lb bags for a 4" deep slab. 

Home Depot sells a 90lb bag for $3.30 which would be $99 for 30 bags.
http://www.homedepot.com/webapp/wcs...3&productId=100318523&N=10000003+90048+527384

I've got all the form lumber, steel stakes, tamper, mixer, screed, screws, and should have some rebar/wire around.. However, I am sure there will be some additional costs :yes:


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## jerryh3 (Dec 10, 2007)

SKINNY said:


> hm...
> 
> I figured the slab would be small enough to use the ready mix sacks and a mixer.. Home depot calculator says for 7x7' I'll need 30 of the 80 lb bags for a 4" deep slab.
> 
> ...


Do you have a truck? If so, you may want to see if you have a U-Cart conrete place around. My place charges $140 for a 3/4 yard cart. No mixing and your back will thank you.


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## NJ Brickie (Mar 4, 2009)

With the considerable weight of a hot tub filled with water, I would use redi-mixed concrete (IMO bagged stuff is junk) and would also pour the slab 6" thick.


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## cruisejunkyjoan (Mar 15, 2010)

*foundation for a hot tub*

We too have purchased a hot tub over the weekend, couldn't pass up the deal.
Our tub is 96 inches and will sit on the ground not our deck.
We are considering doing a, for lack of a better term, "compacted earth" foundation with a pad from the retailer on top.
Will this be okay or do we really need a concrete pad for this tub? We will probably still us the pad from the retailer just for a looks prospective.
Any help will be appreciated.
We will have to contract out the work since we have neither the time nor the experience to tackle this project.


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