When prepping the floor to tile, I came across what appears to be old wood siding between 2 solid concrete slabs in a doorway.It is about a half inch wide a d runs the width of the opening. A quickcrete patch had been over the wood that came up while scraping the floor. What should I do? Try digging as much out as possible and then add concrete into gap in stages?
We don't know how deep the wood goes - it could be an inch, could be 6". But dig down as far as you can. If it's shallow, then concrete will fill up to floor level, which, if you're lucky, will be the same both sides. If it's deeper, dig at least 3" out, and fill as before. If the levels aren't exactly the same, then compensate with more adhesive on the lower side. I'd taper off after a couple of feet if there was a differential of say, 1/4".