Decks, Patios, Porches and Docks - Options for pad for spa

I have a used spa and want to locate it at ground level... considering options for the pad underneath. Would a wood pad of treated 2x4s screwed into 2x4s spaced 24" apart be sufficient? Placed on a couple inches of limestone? Or are concrete footers a must?

Pad needs to be 8'x8' and hold ~5000#. I'm concerned about freeze/thaw underneath shifting the pad and perhaps cracking the spa (frostline is at 3').

Anyone have experience with the Confer plastics handi-spa pads?

Just looking for shortcuts to the usual 4" reinforced concrete pad.

Thanks.

Go with the concrete pad. You have a lot of weight and the concrete pad (properly reinforced on a compacted base) is time proven.

Probably not any more expensive and you'll never have to worry about it once it's in place.

The concrete pad will have to be bonded to the spa which is nothing more than a #8 bare wire attached to the reinforcing wire of the pad and then to the electrical connection area in the spa. It should be marked where the bonding wire goes.

The concrete pad is going to be your cheapest, as well as the best option. (That's from a deck contractor!!)

Thanks for sound advise. I'll go with the concrete slab.