Will removing dirt so i can install a mulch border harm my stamped concrete patio,i live in indiana?

Question

i have a stamped concrete patio,iwanted to install low voltage lights around it .i removed 3 to 4 inches of sod and dirt,12 inches wide,from around the patio,i also removed exsess stone that was under the sod.my concrete guy told me i should not have done this because water will now run under the patio and cause it to crack in the winter.im from northern indiana.he said to use landscape stone,not mulch,to help fix what i did.i wanted to use mulch.should i hire a new concrete guy

Answer 1

You can dig down the few inches..then dig under the concrete on the patio then go get a few bags of premixed concrete at Home depot, that has the reinforced fibres in it..mix it up and pour a 2 inch footing around it making sure to push the concrete up under the concrete about 1 inch where you dug under the slab..only dig under the slab 1 or 2 inches..push the concrete under it to fill..then trowel the outside part down  and let dry..then put your mulch over the new poured "footing"

Answer 2

even with stone the water will get under it, but if the slope is toward the slab then it would have gone there even with the sod, if your patio is higher than the rest of your backyard you should be ok, ask your "concrete guy" what the difference between sod mulch and rock is concerning water intrusion, if your really worried do some more digging and put some 6 mil visqueen under you bed sloped away from the slab