What's the safest way to pour a slab without undermining existing posts [closed]

Question

Im working on a 2 story addition that is resting on 6x6 posts. Unfortunately due to timing I was unable to work out pouring a slab prior to our contractor begining our addition project and pouring the footings. So now I am left with a challenge I am over analyzing :).

Originally I wanted to put a 20'x10' slab or floating deck below the entire addition pictured, however because each footing is only 30" deep a single slab would require excavating below the footings on the left side of the photos.

As an alternative I'm thinking about a 2 tier slab or even a floating deck as pictured, but I am worried about undermining the posts either by surounding them in concrete or by digging too far down against the footings.

What would you do in this situation? The space will be unfinished and mostly used for storage.

Answer 1

I'm not a construction worker but here is an idea: Use a metal shoring posts to secure the corner, then remove the shortest post. Excavate and replace it with a 6'11" post. Now leftmost and middle post are level.

Put a concrete tube around the rightmost post and pour an additional 1'1" of concrete so the top of the concrete levels with the top of the concrete of the middle post.

Now you can level and pour the slab. Assuming 5 inch slab, the whole area will have uniform height of 6`6".

Adding concrete around the post is not going to affect it negatively.

Shoring up the addition with a 1-2 jack posts will ensure you won't be undermining anything while you are replacing the one post.