Deck footings through an existing patio
When a new deck post has to land on your existing concrete patio, there is a common way and there is our way. The difference is what your patio looks like when we are done.
The common way — jackhammer
Break the slab out with a jackhammer, dig the footing, pour it, and patch the hole. That leaves a jagged, obvious repair, and the shock of breaking the slab usually starts a crack that runs out across the rest of it.
Our way — core drill
A 12-inch diamond core barrel cuts a clean circle straight through the concrete. The footing is dug and poured to full depth below it — 30 inches deep, 12 inches in diameter, with a 16-inch belled base — the post is set, and the collar is filled back flush with the surrounding slab. The slab around the cut is never shocked, so no hairline cracks.
What is under that circle: a full-depth pier poured to the same spec as any other footing on the job.
The real thing on a deck we are building now: the core-drilled footing filled and finished flush. The 12-inch core leaves a clean round edge instead of a broken one, and the slab around it is untouched.
One honest note: fresh concrete never matches aged concrete exactly. The fill reads lighter at first and blends over a year or two, but it stays visible if you look for it. We would rather tell you that up front than have you find out after.