Concrete Pad Questions.

[kluzo]

How deep should a slab be to put a Hot Tub and decking around it. It is 10' x 10' slab the other thing I need to know is where to locate the stress cuts. I am told to use 3/4" crusher stone about 2-3" deep but no one has indicated to me how deep to make the pad itself?

[Chas]

From 3 to 6 inches, depending upon the soil conditions.

If you are putting crushed rock under the slab, you can go with a bit less concrete thickness.

I have put in lots and lots of tubs on 3" slabs without any trouble - we have lots of very hard clay soil around here. When I'm installing near the beach - on sandy soil or just sand - we go for 6".

Cut joints every 10 to 12 feet would be the norm.

[ZzTop]

From 3 to 6 inches, depending upon the soil conditions.

If you are putting crushed rock under the slab, you can go with a bit less concrete thickness.

I have put in lots and lots of tubs on 3" slabs without any trouble - we have lots of very hard clay soil around here. When I'm installing near the beach - on sandy soil or just sand - we go for 6".

Cut joints every 10 to 12 feet would be the norm.

Good advice,

I would add wire or rebar for extra insurance against cracking and settling.

[kluzo]

I'll be adding re-bar not a problem. We are in a new sub-division that use to be a farms field. on the low side I may be in the top soil but on the high side (or deep side) I am into hard soil that I needed a pitch fork to break the soil loose. One side is only 6" into the ground then it goes to about 25-30" deep on the other side.

[UnderTheStars]

Check your tub manuf. recommendation as well.  For example, my manuf. says 4" min.   Also, size of your tub may be a factor.  You should also check for a grounding requirement - The rebar or wire mesh should be bonded to a #10 ground wire.

Most concrete guys will tell you no stress joint needed on a 10 x 10.  (for a garage floor 24 x 24 you cut the slab in half both ways.)  Finally, if you are doing the prep yourself remember the gravel goes on undisturbed soil only.  That means where you dig/loosen soil, remove it.  Don't try to fill low spots with dirt.  You cannot compact it enough and over time it will settle and leave a void under that portion of the slab.  That unsupported portion of the slab leads to cracks.

[OnMedic]

Hey Kluzo,

When do you expect the tub to come?

My deck is still in the works, but here are a couple of pics that were taken a week or so ago. We have since gotten the deck finished and trimmed, and a couple of sections of the screen up too. I will be posting more when I am done. We sank our pad 12" and raised our deck 15", so that the top deck is level with the 1st step iside the spa. Our slab is 6-8" thick. That is just the was it worked out after compacting and making the form to be at the elevation desired.




As you can see, still have to build the trap door and tack-up the skirt around the bottom.

[autoplay]

No cold joints are necessary. A 10x10 pad will be a free floating pad.  Specs for expansion joints are every 16' outside appl,20' inside appl. I would suggest you make the depression 6"s,and use a 1-2"  P gravel bed. Then either rebar or wire(rebar is overkill for that small of a pad) If was me pouring/floating the slab.......I would allow 1/8-1/16 of an " per foot,for water drainage. You could always make the pad dead level too,but I prefer to have a place for water to run-off.

If you have the time,water the slab 2-3 times a day.....and keep it covered with plastic. If was me,I would keep it covered 7-10 days. The longer the crystals are allowed to grow,the stronger it will be.

GL

[kluzo]

Tub comes on the 29th however I don't know If I can get the concrete poured soon enough for it to cure properly so I may have to delay the delivery for the week after (My wife will be  )
From what I am told I will be going with about 3" of 3/4" Clear gravel and approx 5" of concrete. Does this sound like an over kill?


Oh ya OnMedic..... Thanx for the specs on the 740. It has been a HUGE help, and your tub looks GREAT!!! Hope you are enjoying it.

[ZzTop]

Hey Kluzo,

When do you expect the tub to come?

My deck is still in the works, but here are a couple of pics that were taken a week or so ago. We have since gotten the deck finished and trimmed, and a couple of sections of the screen up too. I will be posting more when I am done. We sank our pad 12" and raised our deck 15", so that the top deck is level with the 1st step iside the spa. Our slab is 6-8" thick. That is just the was it worked out after compacting and making the form to be at the elevation desired.




As you can see, still have to build the trap door and tack-up the skirt around the bottom.

OnMedic really nice installation!

[cparlf]

I just met with the concrete contractor, we will go with 5 inches think 4000 psi fiber reinforced 11' 6" square with a short connector to the present patio.  This will give two feet around for walking, and allow for landscaping without crowding.  We have heavy clay line in the soil and therefore poor drainage in the yard and the overkill isn't really overkill for a bit of peace of mind.  Hopefully.  The contractor will bisect front to back and cross ways for expansion joints, and will build a total of one half inch front to back slope for run off.

Does this sound reasonable??

Someone should take all these ideas and information and publish a book.