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I need to pour a small (~5' x ~5') concrete pad that will butt up against 2 basement block walls (A&B in the diagram) and my asphalt driveway (D in the diagram). I'm having some trouble figuring out how to frame it correctly as I need it to slope toward a trench drain I will be installing as well.

  1. From my understanding, there needs to be an expansion joint between the newly poured pad and the existing block wall. Would using something like this https://www.homedepot.com/p/SAKRETE-50-ft-Foam-Expansion-Joint-70450004/100674358 be sufficient as screeding surface to get the slope right and an expansion joint?
  2. What should I use to frame side D as it's not a straight line and actually has a gradual angle? Would 1x lumber or plywood be flexible enough or is there something else that I could use?
  3. Once the pad is poured, should I insert the expansion joint material between the pad and asphalt (D) or would some concrete caulk be sufficient?

1 Answer 1

  1. be sufficient as screeding surface to get the slope right and an expansion joint?

No. And neither would the stuff I normally use; Fiber Expansion Joint, 1/2" x 3".

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Tapcon a screed guide board to A (and/or B), at a height that will allow a board that's screwed to the top of the actual scredding board, to ride on it. That's how you screed something with only access to one side. And it's what you put the plank on to reach the corner to trowel it.

Ideally the guide board is an inch or so above the finished surface, otherwise you can't get a trowel in there. E.g., use a 2x4 for the guide and a 2x6 for the screed. Screw a scrap 2x4 to the top of the 2x6 so that it sticks out 1.5". Have fun jiggling it back and forth 3/4" at a time.

  1. What should I use to frame side D

Frame as usual with 2x, well buttressed. Remove later, add expansion joint, and then fill/sculpt by hand.

  1. Once the pad is poured...

You're SoL. The expansion material goes in before you pour. You cut them to length, put them in, and they fall over. Start filling and then stand them back up.

  • Thank you for the thorough response! I still do need expansion joints between the pad and the block walls correct?
    – Yev
    Feb 3, 2020 at 5:24
  • @Yev - 'D' along the asphalt is the only one that could be optional. Do both block walls for sure.
    – Mazura
    Feb 3, 2020 at 22:26

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