Need Help - Sinking a tub in deck

[jparadise]

Im extremely new  to the hot tub world so please bare with me.  I picked up a tub from my mother in law yesterday that is probably 15 years old.  Good news is she had the pump replaced last year and had the control box rewired.  The glass is in good shape too.  But what's in bad shape is the wood skirt and the wooden framing underneath.  I was shocked when I moved it to see that the tub had been  sitting on the ground all that time.  Needless to say, when we moved it, the inside bracing fell out from being rotten.  So my plan is to rip the skirting off and build a deck that the tub shell can "sink" into.

Here's where I need help.  I'm assuming the lowest point of the fiberglass (where you would stand inside the tub) needs to be well supported.  I planned to pour a 3x3 6" slab for that portion to sit on. Would that work?  Is it nescessary? 

Next question pertains to supporting the "lip" of the shell.  First off, how supported does this need to be?  Does most of the weight reside in the middle portion on the cement slab or is there considerable weight at the lips also?  My thoughts are to cement in a 4x4 at each corner of the tub and tie them together with a 2x6 at the top.  The decking would be screwed to this 2x6 and the spa lip would rest atop of the decking boards, while the middle of the tub rests on the cement pad.

So, how does this sound?  Like I said Im new to hot tubs so if any of you think theres an easier way please let me know.  FYI, I want the deck to be as low as possible, which is why I was thinking the concrete pas was the best idea.  Thanks in advance

[wmccall]

Welcome to the forum!  I'm the moderator here, which is kind of like a substitute history  teacher filling in on a calculus class . I know what you are talking about, but don't have a clue how to help. Fortunately, we do have a lot of experts here and you have stated the situation very well. Good luck to you.

[sorebikr]

I can help you part of the way.  Where are you located?  I'm assuming a cold weather climate and you're concerned about frost, yes?

The 6" slab with rebar is perfect for the tub to sit on.  Though I'd suggest if you're going through the hassle of mixing/pouring the slab you build one larger than you need right now, just in case you want to upgrade to a larger tub in the future.  There are also options like this out there:  http://www.ezpads.com/  that have receives overall positive reviews from what I've researched.  But I've also heard from some that if you go that route, don't bother and just use cement pavers.

I can't offer much advice as to what you should do to support the sides of the tub, but here are some thoughts:
You might want to reconsider have the top of the tub flush with the deck for a few reasons.  It increases the chances of a person (or pet) accidentally falling into the tub.  It also makes it a bit more difficult getting in and out of the tub.  Maybe consider having you tub 10-15" proud of the deck to avoid both of these possible issues. 

Hopefully someone else will chime in soon with advice on the rest of the framing.

[jparadise]

Thanks for your responses, Im actually in North Texas so not too concerned with cold weather.  Thats a good idea about the partial recess.  I've been thinking about that option but was turned away because I don't want to mess with building a skirt...plus I like the  fully recessed look.  Any other input is appreciated, thanks

[JulieMor]

It sounds like your tub is structurally supported primarily through the wood frame, as opposed to a tub with a full foam core where the foam transfers a lot of the weight directly to the base.  If you look at the places the manufacturer focused on for support, you should get a very good idea how to support it under and around your deck.  I wouldn't think the shell lip would be the place to support it unless the original frame supports it there.

If you decide to raise it a foot or two above your deck, there are a number of options for skirting the tub, some expensive, some a lot cheaper.  I just spent almost $700 on raw redwood for a new skirt and steps for my tub.  And I still have to resaw, rip, router and cut to length each piece before I start to install it.  At the least expensive end you could use the same material you have for your decking and it would require just some basic tools.  It could take a beating and blend well with the deck.  And if your tub shell is designed for surface mount, it would make the skirt work a lot easier.

Obviously the base is important and pouring a concrete pad would be best.  You shouldn't need rebar though.  A simple concrete 6x6 wire mesh should work well.  Just make sure you put down some 3/4" limestone or sand underneath.  I would suggest a minimum of 4", though 6" would be better.  Compact the sub base before pouring the concrete.  If you only have black dirt when you dig out the pit, you may need to dig down to clay or sand.  Black dirt is not a good base for holding weight.