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I have a small (cca 5 sq ft) basin in front of my basement door. It is between a staircase (bottom of the picture is the first step riser) and the door threshold (top of the picture near where it's etched "MCMIX").

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The edge near the staircase, however, was not properly graded when the concrete was poured and is slightly below the level of the drain so it collects a small puddle of water.

Which material should I use to raise the level of concrete in that area with just a skim coat? I was thinking self-leveling compound but I actually don't want it to be level but graded just a little. Can I just use a skim coat of regular mortar/stucco or is there better, more durable material?

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  • 1
    if MCMIX is 1909 it has aged well.
    – Jasen
    Sep 8, 2021 at 4:30
  • 1
    I thought it was someone's name: McMix
    – jwh20
    Sep 8, 2021 at 12:26
  • 1
    What ever material/process you use, I would consider covering the whole basin so it doesn't look patched. Sep 8, 2021 at 12:32
  • Related. Possibly dupe?
    – FreeMan
    Sep 8, 2021 at 14:08
  • "MCMIX" is indeed the year the house was built but it has been receiving A LOT of TLC in the last 14 years it's been mine
    – amphibient
    Sep 8, 2021 at 14:26

2 Answers 2

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You can use self-levelling compound.

Mix it a bit thicker, so hold back some water when mixing in a bucket.

SLC nominally flows like pancake batter but you can make it thicker like peanut butter.

Make sure you scrub the concrete clean, and roll-on or brush-on a primer, mix-in a primer or get SLC containing primer (read the label).

Keep a trowel handy and work it after pouring. You have a small area, with a firm (concrete) base, so this is quite doable. Would be handy if you make a depth gauge, like a nail with markings, set at the appropriate height for the desired slope and the slope of the base.

You might need some sort of guard ring around the drain, and definitely tape it off.

Alternatively you can lay a tile mosaic, and combine function with aesthetics.

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  • Having not used SLC (no, not Salt Lake City - I've been there), will it bond sufficiently to the concrete to be walked on, subjected to freezing and snow, etc without any sort of reinforcement or attachment to the existing concrete? I can envision it cracking away in a couple of years, especially in the thinner areas right at the drain. AIUI, SLC is usually covered by something else that would protect it from direct wear.
    – FreeMan
    Sep 8, 2021 at 16:34
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    @FreeMan exterior SLC can be used for topping/finishing. OP should adhere to the label, and minimum thickness. Best to seal with concrete paint. Prepping the base is very important: clean, roughen-up, and prime.
    – P2000
    Sep 8, 2021 at 18:04
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You can use either product you have mentioned, but the important thing is - no matter what type of mortar you are going to use, you need to prepare the surface well to receive it and to keep it stays in place. I wouldn't trust the bonding agent applied on a smooth hardened surface. You should roughen/chipping the surface to a magnitude of about 1/8", thoroughly clean and moisten the substrate, then apply bonding agent and mortar. Cover the drain while working around it.

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