I have a concrete slab to pour. Around most of the edge I am using some edging which will give me a solid slab to tap against to make sure the concrete is level (with a slight fall to ensure water runoff).

However, one edge is completely against an existing wall, as is half of another side at the corner where they meet. Which means I can’t do the normal method of tapping along the edge of the former to correct the height/flatness of the slab.

I could put in a strip of wood, but that would not be ideal as the wood would either be left there and look ugly/rot among other things. Or I could find some way to pry it out of the slab (not sure how to do that) and then find some way to fill the hole it would leave behind.

What should I use to give me a suitable guide to tap the top of my concrete flat? Would some brick or stone be a suitable option? Or is there an alternative to tapping along the top of the concrete as I pour it?

  • 1
    Would place a chalk line where you want and then use screws/nails/silicon caulk to hold a straight edge on. Then can tap/level away.
    – crip659
    Commented Sep 18, 2023 at 14:52
  • 1
    "Tapping concrete flat" isn't a valid masonry finishing strategy. It results in too much water floating to the top and a weak surface. Pour, float, trowel.
    – isherwood
    Commented Sep 18, 2023 at 20:06


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