# Small concrete slab for hot tub....any tips?



## vitamin sea (May 23, 2004)

My beautiful bride and I have put money down on a new backyard spa and I plan on pouring a small (8.5' X 8.5' X 4") concrete slab as a base. Even though this will be the first slab I have poured myself, I think I can pretty much handle building the form and getting it square and level. I also will be bringing the electrical up through the slab and it will be fed through a 50amp GFCI breaker.

I plan on using 6" X 6" steel mesh as the structural steel and I will have it elevated with the small supports to make sure it ends up in the center of the slab. 

I plan on getting the concrete to the house with one of those small concrete trailers that you can get from the rental place.

I guess the only real question I have is do I need any expansion joints in a slab this small? I'm guessing I don't but thought I'd get input from the 2Cool brain trust.

Any advice or tips you can offer concerning this entire process would be greatly appreciated. I'll try to do some before and after pics.

Again, thanks in advance,

Rex


----------



## RB II (Feb 26, 2009)

No you don't need an expansion joint. I would build a block out for the electrical conduit to pass through the slab, 6"x6" or so. Considering that this is for a hot tub and the fact that it is so heavy, I would consider beefing the slab up a little from what you are describing. Maybe 6" of concrete with wire mesh, or 4" of concrete with 3/8" rebar 16" on center, or 4" of fibermesh concrete with wire mesh. In any of these scenarios, I would also encourage that you put in some kind of beam around the edge, maybe 12" deep x 12" wide with a piece of 5/8" rebar or two in the middle of that. I understand that all of these things cost more and take more time, but the last thing that you want is for the foundation to break and cause problems with settling etc. and have to redo all of it.


----------

