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I'm planning to pour a concrete slab along a brick wall and need to plan how I will screed it smooth.

Three sides of the rectangular slab will have a removable wooden form, but the fourth side is against a brick wall. The question is: what to use as a screed guide along the brick wall?

Any material I put there will tend to get concrete packed up against it. So it either needs to be something sacrificial I can just leave embedded in the slab, or be able to pull out after the screeding is done but before the concrete has set hard (and then touch up just that small area).

The length of this side is about 18' (6m).

The simplest option would be to screw a 1/2" board to the brick and abandon it in the concrete. But just in case any moisture wicks in that seems like a poor choice.

This edge will be covered in the end so appearance isn't important.

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The conventional way to handle this problem is to use a length of 1.5 or 2 inch diameter pipe as the screed reference level. This pipe sits on top of a series of stakes that you place in the ground in a line a few inches from the brick wall. The stakes are pounded in so that their tops are the pipe diameter below the intended concrete height. Two nails in the top of the stake are set in on the sides to keep the pipe from rolling off the stakes.

The pipe does not need to be the full length of your slab. Instead as you pour the concrete from one end you screed along and then can pull the pipe back to the next stake. After you pull the pipe you toss some additional concrete into the gap where the pipe was and float trowel that flat with the rest of the surface.

The small stakes and nail tops just stay in the base area of the concrete slab.

The idea to place the pipe say 6 inches away from the wall allows for easy back and forth working of the screed. (If you just had a thin board along the wall it would be very difficult to keep the screed on the top of that narrow board and there is no opportunity to use a sawing action of the screed which is necessary to work the pebbles in the concrete down from the surface).

  • Excellent detail & description, thank you. How long can/should you typically wait before filling in the gap left by the pipe? – DaveInCaz Jul 12 at 14:47
  • @DaveInCaz - We used to pull the pipe and fill in right after screeding but before floating. – Michael Karas Jul 12 at 16:10
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Use the board as you suggest, but make sure it is removable.

Then decide on how to fill the gap, a sloping surface from the wall etc

  • Making sure it is removable is the trick... do you think just leaving screws as close to the top as possible and getting them out, then manually patching it up is best? – DaveInCaz Jul 12 at 12:16
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    A bracket or two (or 3 or 4) and a couple of screws that are easy to get to. Also a thin strip on the face to reduce the concrete "sticking" to the wood surface... – Solar Mike Jul 12 at 12:18

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