Need concrete pad slope advice

[bradleyheathhays]

I'm getting ready to pour about a 10' x 20' slab in my backyard that's to serve as the base for a lightweight aviary enclosure, or really big outdoor bird cage. I'm tight on funds getting this whole thing done, so I'll probably just shoot for 3" thick. I just ran a water tube level between two of the opposite corners, and I'm seeing a 12"+ grade difference, which is a good deal more than I had anticipated. The floor needs to be sloped somewhat for water runoff after cleanings, but 12" over 22ft may be too much.

So my question is...what kind of slope should I aim for that won't feel TOO tilted when walking on it, but won't kill my back digging out the foundation enough to make it more level?

 

[jttheclockman]

1/4" per foot works well for patios so why not for what you have. Plus if you do a broom finish broom it at that slope.

 

[MRDucks2]

Keep in mind that with a 3" thick outdoor slab around Lexington you need to make sure that not only is the slab sloped well away from the house (John's recommendation is fine) but that you need to ensure you do not get/trap water under the slab or it will suffer from the winter freezes.

 

[gbpens]

I suggest sing a 6" wire mesh in something that large. If and when it cracks it will separate.

 

[jttheclockman]

Oh you better put wire mesh in that size of a slab.

 

[Tach]

Prior to the pour, a good base of gravel with a really good tamping will definitely help. The 1/4" per foot slope should be more than sufficient. I would consider a smooth troweled finish if for no other reason than ease of cleaning. A simple water hose will work on a smooth finish but the broom finish may require pressure washing.

 

[bradleyheathhays]

Thanks for all the advice guys. I'll probably shoot for 1/2" per foot slope and a smooth finish for ease of cleaning.

But what is this about trapping water under the slab MRDucks2? This'll be my first large slab and I haven't heard of this before. How do I mitigate the ground water freezing?

 

[MRDucks2]

You can achieve it simply by ensuring your ground is sloped for drainage as well as the slab. If you have a perfectly flat spot for your slab and taper the slab only, you can get water underneath. Make sure the grade/slope of the ground has your slope and pour a basically flat slab on top, or slope both the ground and the slab to achieve your total slope. Maybe not the best explanation but hopefully you get the picture.