I finally figured out why my buddy tapes his edges so far back

I was talking to an old finisher named Sal at the supply house last Tuesday and he said he leaves 3 inches of tape on each side of his control joints because the concrete breathes different near the edges. Made me realize I've been getting those hairline cracks near my forms because I was taping too close to the edge. Any of you guys tape your joints further back than the standard inch or am I overthinking this?

2 comments

2 Comments

hart.taylor15h ago

Taping those edges back is something I started doing after cracking a slab on a hot morning. That old finisher had it right, the concrete near the forms always seems to move differently during the cure. I usually leave 2 to 3 inches of tape on each side and I get way less tight cracks along the forms now.

adams.taylor8h ago

Scrape that tape off clean before you pour too, or it'll leave little rips in the surface.