Hot tub base

[Mikes145]

I had a hot tub on my deck for the past 10+ years and am getting a new tub and placing it next to the deck in the yard.  My plan is to make a frame out of treated 4x4's, put down  4" of crushed concrete or similar compactable base after taking out the grass and topsoil, put the frame on top of it, put  a couple inches of slag sand on top, then top with 4x8" blocks (4" thick) from Home Depot.  I can't see that a concrete slab being much stronger and I don't want to wait several weeks to put the tub on top.  Has anyone else here done the same?  Thanks, Mike (first time poster).

[Dr. Spa™ Ret.]

It's not about strength as much as it is about remaining FLAT. A concrete pad may settle, but it will still be a flat (though, unlevel) surface. If a couple of pavers settle, the surface will not longer be flat and it could cause a spa to crack.

[mpp]

Use an EZPad (www.ezpads.com). Much cheaper than concrete (a bit more expensive than pavers) but completely flat and easy to return to grass if you ever move the tub again. Despite their flimsy look they are incredibly strong.

[clover]

with proper preparation and compacted base, which is of course level, placing a spa on it with water is a 5,000 pound object with compacting pressure at the perimeter of the base exerting equalized downward force.  You will be fine. 

However, mpp's suggestion is similar, if not less in cost, but much easier to put in and take out if/when necessary.

Frankly, in 30 years, I have never seen a shell that cracked because of where it sits, but I am sure it's possible without proper support.

Whatever you do, there is only 1 guarantee, the water will be level.

[Nazz26]

If you do the work yourself a 10'x10'x6" concrete slab will cost you approximately $450.00
80 80lbs bags of cement at $3.80 a bag=$304.00
Ton of crushed stone=$50.00
Framing and concrete support material=$35.00
Rent a cement mixer=$50.00 a day
Back pains when complete=priceless but painful
The cost of a hot tub 8'x12' ez pad=$625.00
You still have to do the same ground prep work no mater which way you go.
My 17 yr old son and I did the work in two full days and it's not that hard to do.
Just for you to consider. 

[mpp]

If you do the work yourself a 10'x10'x6" concrete slab will cost you approximately $450.00
The cost of a hot tub 8'x12' ez pad=$625.00
My 17 yr old son and I did the work in two full days and it's not that hard to do.

Although teaching your 17 year old son how to frame and pour concrete and the value of honest day's hardwork is certainly priceless,
overall it means 2 people x 2 days for a $175 difference means you value you and your son's day at ~$45 each.

If doing it alone or you value you're time more than $45/day, go with the EZ Pad.

Not to mention the cost of driving to Home Depot, driving to the rental place and then back and that time...sucks. On mine  I  did do the base myself but the hot tub guys brought the EZ Pad with the tub included in the free delivery.

[Isaac-1]

2 days seems a bit excessive, depending on how much prep work you have to do.  A few years ago I poured a similar sized slab for a generator (4.5x12), there were 3 of us working on it, and 2 of us had back issues, the 3rd was an 18 year old that spent most of his time texting.  Basic ground clearing was done one evenings with 2 of us working for maybe an hour, the main part of the project was done the next day, we started framing using scrap wood at around 9 am, and we were pouring by about 10:00 or so using an under sized cheap mixer that woudl only mix about 60 pounds at t time, which was a pain since we had 80 pound sacks.  We finished pouring at about 3 pm, took about an hour to scrim and broom finish afterward, and everyone else was gone by 4:30 pm leaving me to clean up.

[Budule]

See how much your local concrete company would charge to bring you 2 yards out......

[Dr. Spa™ Ret.]

80 bags of concrete? I go down to the concrete place and pick up a trailer full of already mixed concrete. Drive home (watch the curves, it can spill ;-) and dump it in the form.