Best foundation for hot tub

[SDOutdoorsman]

I’m sure the best is probably a concrete slab but this tub will be moved probably within the next 2-5 years, is gravel or sand or a pea rock base the next best? Should pacers be put on top of that?

[Sam]

Don't use sand.  Just like when you go to the beach, sand gets everywhere.  Sand and moving jets or pump seals are not a good combo.  3/4" to 1" crushed rock is the best, imo.  Pea gravel is too spongy.  The 1" rock reaches like 80% compaction just from it's own weight.  Pea gravel is just harder to work with when sliding a 1000 lb spa into place.  The leading edge digs in. You leave footprints when you walk on it.

Make sure to frame it in with something to prevent washing out or settling.

[Tman122]

Don't use sand.  Just like when you go to the beach, sand gets everywhere.  Sand and moving jets or pump seals are not a good combo.  3/4" to 1" crushed rock is the best, imo.  Pea gravel is too spongy.  The 1" rock reaches like 80% compaction just from it's own weight.  Pea gravel is just harder to work with when sliding a 1000 lb spa into place.  The leading edge digs in. You leave footprints when you walk on it.

Make sure to frame it in with something to prevent washing out or settling.

Yea, I also like compacted class 2 limestone type gravel. Then build a nice clean 4x4 and 3/4 plywood platform, bigger than the tub. Treated wood of course. 1/8" per foot slope.

[NBonugli]

The tub I ended up getting is quite large and "wet" weight is over 7000lb. (MasterSpas MP LSX900) I didn't take any chances. I excavated, put down 1' + of compacted gravel,
installed a pretty extensive rebar cage consisting of #4 and #5 rebar, and 4000 PSI concrete. Yeah...it's probably overkill, but that's how I do everything.

Nick B
Middleton, MA

[hobble23]

I put in 5000 PSI concrete rebar crossed in 1 foot increments.  Overkill bigtime.  Cost me $300 only because I was getting some stamped concrete done at the same time..  Quote without that would have been 700 or so I think.