Spa Deck Requirements

[botalvr]

Hi all. Hopefully not too far off topic, as I will be using my tractor for some of this one:

I am considering a new spa which will weigh in excess of 4000 lbs. I want to build it myself, but am unsure of the details of the support to the deck/platform on which it will sit.

It will be 8'x8' in size, level with the ground in front and about 2' off the ground in back, due to the slope of the yard at that point.
My rough idea is that I will need 6x6 posts sitting on all corners as well as one on each side between the corner posts (a total of eight), all atop concrete support footers. Then a 2x12 doubled frame, with 2x12's 12" on center, with the "normal" decking boards on top.
Is this too much? I don't want any trouble later, but even a deck that's only 8'x8' built this way will be expensive.

Thanks!

 

[texastomtom]

Sounds like you have the perimeter covered...

My spa also has 'weight bearing points' in the center.

I think I would consider some support in and around the center of the spa.....

Would not be hard to add now,,,

tom

 

[MarkV]

Danny,
I’m not an engineer, just a guy that has worked with wood a long time, so take this for what it is worth. With an 8’ span and joist spacing on 12” centers I think 2x10’s would be more than enough. If you want to stay as close to the ground as you can I think doubled up 2x8’s on 16” centers would be plenty.

You said one side would be at ground level. Have you considered pouring 3 footings on that side and attaching your perimeter beam directly to the footings with brackets? No chance of lateral movement that way and you minimize the step up to the deck. I suppose frost heave could be a problem in you area, we don’t have that in Georgia. Unless you plan to set the 6x6’s below the frost line it is going to be a floating structure anyway.

When we got our spa the manufacture had recommendations for deck construction. If you have picked a model you might check and see what they say.

Another thought about the size of the deck. Our spa is considered a 5 person and is roughly 7’ by 7’6”. An 8x8 deck would be mighty small for getting in and out of the spa. There is enough of a step over we have added some simple steps to make that easier.

MarkV

 

[dmartin88]

An alternative thought- we leveled the ground where we put our spa, then set it on a 6 inch deep bed of gravel with wood framing to keep it in place. Has been there about 4 years and just as level as the day we put it in place. We then built the deck around the spa leaving about 18 inches of the spa coming through the deck- made it a bit easier to climb in and out of and didn't have to account for the weight of the spa for the deck construction. In your case, this would involved bring the ground level down a bit but just another idea. We made a trap door in the deck next to the side of our spa where the access to the pumps and other equipment are located. I can post some pictures if you're interested, good luck with the project.

 

[JDgreen227]

DannyDan,

I tried to reply to your post early this morning and my spouse picked up the phone upstairs about ten seconds before I could post my opinion....I warned her to stay off the line for about the next half hour....until I can post this.

You are not off topic at all if you use your tractor for the spa deck, I got a lot of use out of my 4210 last fall building mine.
We have a Hot Springs Grandee, 500 gallons, the tub size is 8X8 and it weights 5000 lbs full of water. What I did was:

I wanted the tub to sit about 30 inches off the ground on one side, the slope would have caused some problems unless I had a firm base under the tub. I laid out a square area about 9 1/2 feet each side, and dug 4 foot deep postholes for 8 4X4 treated .60 retention posts....then I mixed up concrete and poured an eight inch thick footing for each post.

When the footings had cured, I set the posts into the holes and built a "retaining wall" around the outside of the posts, using mostly treated 2X10X10 beams and 5 inch hot dip galvanized timber spikes. I used long bar clamps to pull the beams tightly together lenghwise before spiking them to the posts. When the square was finally nailed together, I filled the postholes with more concrete just below grade level.

Then I drove my JD and loader back to the end of my property, where I have hundreds of old concrete blocks and many tons of broken concrete chunks. I used the blocks to line the inside of the wall at the bottom, holes pninting up, and gilled the holes with gravel. Then I hauled up about 6 yards of broken concrete and backfilled the interior of the wall, fillinc the open spots with gravel and tamping it down.
When the concrete was about 8 inches from!the top of the brame, I filled it with about 4 anches of gravel and tamped it dnwn, then put in a row of wire mesh and 0 lengths of 1/2 inch rebar, bracing the rebar with form ties and stapling the mesh to the top 2X10.

Then I had two yards ob redi mix delivered to fill the frame to the top, finished it off and let it cupe.<br /:
It's a good idea to make whatever you buihd larger than t`e tub itself, it makes at easier to put the cover, etc. on and off and looks better.<br(/>
The cost was reasonable...treatad posts( about $40, treated beams, about $120, nails, mash, rebar, etc. about $80, and the concrete was $75 per yard. Gne of the reasobs I wanted the top to be concrete was I would naver have to paijt it, although I did apply two boats of Thompsobs Water Seal bedore moving the pub on the slab.4br />
I hope this cives you some ideas. 0img src="/forums/images'graemlijs/smile&gif" alt="" />

Bill

 

[RobertN]

I will second this idea.

We set our spa 1/2 way in to our deck. The seat of the spa is at the same height as the deck. We do not use a step; it is simple to just step over the edge of the spa and righ on to the seating shelf.

Our case was different; our deck is 5' off the ground. We had a contractor frame in the hole for our spa(ours is round), and cut the hole in the deck. Then, he built a second "deck" that the spa actually sits on.

It is great. We were originally just going to reinforce the deck, and set the spa on top. This works so much better!

 

[RobertN]

I will add more description of what we did. Our spa is round. We had it 1/2 inset to the existing deck. Part of the deck railing was removed, and a second deck, which the spa actually sit on was added. There are two steps down to that lower portion, and it has room to walk around the spa; the maintenance panel is on that side of the spa. Railing was added to match the existing deck.

Hopefully the pictures are worth a 1000 words /forums/images/graemlins/grin.gif

 

[RobertN]

This kind of shows the steps and lower deck. Note lower deck is still a couple feet off the ground. It also goes under the existing deck, and has structural suppot tied to the main deck.

 

[RobertN]

From the other side...

 

[dmartin88]

Here's a picture of our spa mounted on the ground but extending through the deck. The platform behind the deck allows us to slide the cover off without having to lift it up.