cement slab leans....any suggestions?

[tstiffler]

We had a 10 x 10 cement slab poured 6 yrs ago when we put in our landscaping, always with the intention of putting a spa on it.  The slab has a gradual 2 inch lean to it for drainage.  We didn't realize at the time, that this gradual lean would be a problem when it came time to installl the spa on it.  We have since learned that the pad must be level.   Hubby is looking at building a  deck on the cement slab.  He plans on using 4 x 4 and cutting them from 3 inch on one end to 1 inch on the other to compensate for the lean.

Any other ideas?   It  was suggested that we use marine grade plywood, have others used this material in building decks for spas?

Any help would be greatly appreciated.  

[Gman]

How big is the tub? 10x10 with a 2" lean may not be too far off for a 7x7 tub, you may be fine or just need a shim.  I'd check just the actual area where you need it to be level and see how far off it is...

[samhunter]

You could also pour 2 new inches of level concrete on top, just be sure you apply a bonding agent.

[Brewman]

Mud jacking?
Brewman

[tstiffler]

The spa we ordered is the Optima and it's 7.5 ft square.  We talked with the dealer about putting a shim under it and he didn't think it was a good idea.

We also tossed the idea around of pouring new concrete over the old but were'nt sure if the new concrete would stand up to the weight of the spa or just crack.  But we are back to this idea, because it seems the simplest.

You mention a bonding agent, What is this? Is it something you add to the mix?

Mud Jacking??

Thanks for your help

[Spatech_tuo]

I saw one person build a "box" slightly wider then the spa pedestal with 2x6s. He ripped them on the slanting side so that the top was level. He bolted it to the concrete and then filled it with pea gravel and set the spa on that. It looked fine and worked like a charm.

Whatever you decide, consult with your dealer.

[Brewman]

Mud jacking is where a crew comes in and drills a couple holes in the slab, and injects a liquid "mud" under it, to raise it back level.  Not sure where is lies costwise, or if you can do it to a slab that is will be holding up a spa.
Brewman

[nicker]

I personnaly think that for that size tub a 2" slope is not all that much.   I would say as long as you have your filters or skimmer on the low side you would be ok.

What do you others think?

[Drewski]

I'd build the "platform" that Spatech "the UNREAL one" suggested.

The reason why I say this is because 2" will probably become an issue to tstiffler (STIFFLER'S mom? -- American Pie? -- GOOD nick!) simply because she knows it. If it was me sitting in the tub and the water looked "slanted," every time I'd get in I'd think MAN, I should have built that platform. Maybe I'm just obsessive?

Making the platform would be pretty easy, I'd also think about putting some drawers in for storage, etc.

Spatech T.U.O, why the gravel?

Good Luck!

Drewski

[Chas]

The deck is a fine idea: it will take care of the lean and support the tub. Yes, marine plywood will work. But if hubby is already set up to cut the 4x4 material into wedges, I would have him consider an easier and less-expensive method:

I would start by setting the spa level on some wood blocks just at the corners, as low as you can. If one side of the spa or one corner is still on the slab, so much the better.

Then measure and cut wedges out of PT lumber and slide them in till they are snug. These should end up being just over an inch or two on one end and go to 'nothing' on the other end, and they should be long enough to reach from one side of the tub to the other. Cut them a big long, slide them in and mark them, then pull them out to trim for length. Sounds hard, it's really not.

Depending on the model of spa, you may only need three or four of these. Larger model spas, you may need one every ten inches or so. Be sure you don't block the open space between them, you need to allow any water to still flow out from under.

BTW, I have told customers to pour the slab 'laser level' for years, and very few ever get it. I have talked to HotSpring about this recently and found that they are of the opinion that a little slope is better - it keeps water from pooling under the tub.

I know my spa at home is on a dead-level slab, and it does pool water underneath. Fortunately, I tend to get a new spa every year, so it hasn't hurt any of them yet.

[Spatech_tuo]

Spatech T.U.O, why the gravel?

The pea gravel is what you level and you set the spa on the gravel. The box is ripped to be level but really that's just for to hold the gravel in place and ripping it to be level is only for looks as the point is you create a level base with the gravel. Simple, easy, effective.

[JJ]

Since my slab is (or will be) next to the house, I was afraid to tell them to pour it level, because I know from previous experience that it will never be level.  I was worried that it would end up sloping toward the house.  I plan on 1/2" over 10 feet away from the house just to keep the water moving in the right direction.

[Spatech_tuo]

I plan on 1/2" over 10 feet away from the house just to keep the water moving in the right direction.

I agree with that number as it'll helps drain the overspilled water and a very large spa is typically only about 6' in length on the INSIDE of the spa at the waterline so you'd see 1/4" to 3/8" slope of the water inside the spa. That is really pretty negligible and won't cause you to have to keep the water high on one end just to submerge the jets on the other end.

[autoplay]

My slab pitches 1.25 inches in ten feet.  Thats's less that an 1/8th per foot.  Codewise.......inside is 1/8th" per foot....outside is 1/4th" per foot.

I have my spa inlet/filter on the low side,and it's barely noticeable. I prefer a little bit of pitch,as it keeps the water from pooling in and around the spa.

Skimfloat it with multi-purpose thin-set.......place spots etc at connecting points,points are level with each other.

Then after you have it prefectly flat and level,install wirecut pavers in a basketweave pattern .

Can't wait to see the pics

[tstiffler]

Thanks everyone for all your help and suggestions.  We haven't yet decided which direction to go in, but I'll let you know.  Electrician was over today, he quoted about $800,  but could go higher once he sits down and writes it all up.  Pretty much what we expected and probably will be higher.  

It will all be worth it when Optima is up and running.  Should here in a couple of weeks when it's ready for delivery.

Hey Drewski that was pretty funny about the 2 inches.  When American Pie first came out, my son's teenage friends would crack up when they called me Mrs. Stiffler.   Ya know, Every inch counts