New Shop Slab with slight slope

[CrissCross]

hello every one. I need some advice I have done about 3 months worth of research on poring a concrete slab for a shop.

The specs are.
I slab that is 20'x20' 5" thick.
Now I have staked the area and have ran a line level all the way arround and was well supprised to find that even tho the ground looked about level it is way off.

At the lowest point I have 5" above ground and at the highest point I have about 13" above ground so my question is about doing the footers I was planning on putting 16" footers but not sure how to approach this. On the low sde do I just dig a trench that is 16" below ground and then on the hight side just dig 8" below ground? or do I still dig 16" below ground on that side as well and if I do then on that side my footers become 16" in ground and then 8" above ground for a total of 24".
Just need some advice. Everything that I have been told is do the footers all the same but just dosent feel right.

Thanks for any help.

[Rich]

Your footing should be all the same level. 16" deep footings are pretty big. We typically pour 8" - 10" deep footings.

[CrissCross]

Wow. Lets Say I go with a 8" footing does this then mean that I am going to have to back fill consideing on one side my level line is 5" above ground and my other side is like 13" above ground?

[Sweep]

Where do you live?

[CrissCross]

B/CS Texas

[VALENT]

YES, you will need to backfill. Unfortunately, when you backfill it is very important that you compact that ground thoroughly. Even though in this case we are only talking about inches of sand. You will probably want to have some clean sand delivered that will allow you to level out the area beneath your slab.

[Zatol]

Backfill with washed stone... It is self compacting and you will never worry about it settling under the concrete slab.. Just my 2 cents.

[CrissCross]

Ok will be getting started in a week or so I just want to make sure I got this right ok so on one side I have 13" above grade so with that a 12" footer would be in the air so I am going to back fill that then my footer on that side would basicly be about 4" below grade and 8" above grade. Is this right. ps thats a 5" slab on top.

Now on the other side it is a diffrent story. It is 5" above grade now so my footer on that side will be 12" below grade.

Thanks again for every ones help. Hust cant afford to do it over if I mess it up lol :)

[11chaos]

Hope it came out okay. If you haven't placed the concrete yet contact me I have some pointers for you. Later