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Author Topic: Correct way to build a platform base for spa?  (Read 15521 times)

sfsdcris

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Correct way to build a platform base for spa?
« on: April 20, 2005, 07:28:57 pm »
I'd like to install my spa raised about 1 foot above ground level, and build a deck around it. Are there stock plans for such an project?

I'm considering building a gravel base, held in place by pressure treated wood, and the top 3-4 inches laying down cement.  Any thoughts? Wrong way to do it?

-c

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Correct way to build a platform base for spa?
« on: April 20, 2005, 07:28:57 pm »

ebirrane

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Re: Correct way to build a platform base for spa?
« Reply #1 on: April 20, 2005, 08:49:58 pm »
One very big consideration is going to be the size of your spa. If you've got a 450 galloner or more, that'sa bit of weight.

The first thing to do is pick a spa. Once you have picked a spa, you need to find out from the dealer what kind of bases will and will not void the warranty.  For example, my HS grandee could not be shimmed and could only be installed on a slab or a reenforced deck because of how heavy the thing is.

My friend has a sundance cameo and he had 2' - 3' (2' in front, 3' in back to make it level) slab poured to hold the tub. It works just fine for him, and he is on year 3 with it. But, he had a professional pour it.

I did my slab myself, but it was only 3-4 inches off the ground.  To dig it I:

1. Checked with building code to make sureyou don't need a permit. Since mine was only 8'x9' I did not needone.
2. Dig a 8" base with a 12" moat (footer) all around it.
3. Tamp it.
4. Drop in 4" of drainage rock.
5. Tamp it.
6. Cover the rock with thick plastic sheeting.
7. Weave/tie a .5" rebar mesh with rows and columns every foot. Use holders to hold it 2" off the rock.
8. Fill it in with concrete.

That *might* be the same process you use to build a 1' or higher slab, but you might need deeper footers, or more rock, or you might be advised to pour the concrete in 2 steps.  

If you call a contractor out to price the work, they will usually tell you what they need to do, usually from the standpoint of justifyingthe expense.  Then, if it is too expensive, you have alistof what you would have todo to build ityourself.

The manual labor, though, was impressive.

Good luck.

-Ed

obi wan

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Re: Correct way to build a platform base for spa?
« Reply #2 on: April 21, 2005, 12:45:25 pm »
i have a 500 gal 7.5' square niagra. i built my own 8'x8' "spa pad" approx 7' away from the current deck. i used 9 dek blocks, 2x8's for joists, and 2x4's as decking (all pressure treate lumber) then bridged the gap to the deck, making it a step up from existing deck level. have about $130 in the pad, and another $100 os so in the decking to connect the old deck to the tub frame. approx 2 hrs to put it up. we planted bamboo along 1 side for some privacy.
the hardest part was leveling the 9 blocks..... ::) ;D

tonyp

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Re: Correct way to build a platform base for spa?
« Reply #3 on: April 21, 2005, 02:56:55 pm »
My existing L shaped deck was about 2 feet off the ground.  I put my HS Envoy in the cut-out area.

I raised the area (12 x 16 ft.) about 6 inches by outlining it with 2 x 6s.  

I built a frame for the spa out of 6 x 6s with 2 cross pieces to catch all the shimming points for my spa.  This information was in the HS pre-delivery manual available from a dealer or online.  

I then backfilled the whole area with gravel.  When the spa was delivered no shimming was needed.

I used the area all winter this way and last weekend I put decking over the gravel adding some 2 x 4s for nailing and support.

Hankster

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Re: Correct way to build a platform base for spa?
« Reply #4 on: April 21, 2005, 09:49:24 pm »
Thanks ebirrane for the information about the slab.  Marquis is one of the spas I am considering and their instructions say to pour a "reinforced" slab.  I assume that means rebar.  I was wondering if others reinforced their slab or would unreinforced concrete be sufficient?

Drifter

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Re: Correct way to build a platform base for spa?
« Reply #5 on: April 21, 2005, 11:30:34 pm »
Here's what I did. I poured a 9 x 9 slab of 6 inch concrete. I then used 16 evenly spaced cinder blocks as a base. I then used two 4 x 8 sheets of marine plywood 3/4 inch thick. (Costs about $80.00 per sheet). I got that from my dealer who had a printed out sheet from one of the manufactures. One nice thing was that it made the electrical hookup easy from underneath. I ran conduit through the concrete and then drilled up through the plywood. It's very Flat and stable and level.

dirtrubber

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Re: Correct way to build a platform base for spa?
« Reply #6 on: April 23, 2005, 08:01:41 am »
You can have the concrete delivered with fiberglass reinforcement added from the batch plant for a small additional charge, it actually works pretty good and should meet your needs but always check you local codes to make sure.

ebirrane

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Re: Correct way to build a platform base for spa?
« Reply #7 on: April 24, 2005, 12:36:13 am »
Quote
Thanks ebirrane for the information about the slab.  Marquis is one of the spas I am considering and their instructions say to pour a "reinforced" slab.  I assume that means rebar.  I was wondering if others reinforced their slab or would unreinforced concrete be sufficient?



re-enforced, to me, means rebar. It's relatively cheap and you can cut it with a metal-cutting blade on your chop saw (just watch out for those sparks!)

Someone else mentioned fiberglass re=enforcement.  Our concrete was "aerated" and had fiberglass added. This was what the contractor recommended and added very little to the overall price.

I don't know the ill effects of not using rebar. At least a greater chance of surface cracks and, maybe, a greater chance of structural cracks.

-Ed

Hot Tub Forum

Re: Correct way to build a platform base for spa?
« Reply #7 on: April 24, 2005, 12:36:13 am »

 

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