The yellow material in the picture is stucco on my house. What is the gray material below it? Is it also stucco or is it mortar or concrete? It seems harder than stucco, but I am not sure. I have nail holes in it and I need to fill them. I am thinking about using stucco patch kit to fill the holes, but perhaps I should use concrete or just an exterior silicone caulk? Thanks!

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    Looks like the same stucco only not colored the same or at all. Or this is the intermediate coat of stucco ("scratch coat") and the final coat was not applied. Jan 28 at 18:23

1 Answer 1


Stucco is mortar. The painted stucco layer beside the removed trim is too thin to account for the scratch coat and brown coat. I conclude that the trim was installed over the brown coat, making the surface material mortar. If you're putting the trim back, I might dab some silicone in there if I was feeling diligent that day. Would I travel 5 minutes to and 5 minutes back from a store to get silicone for plugging the pinholes? No.

  • Thank you! Can I fill the nail holes with stucco and let it dry in and blend? Would that be the best option?
    – pkout
    Jan 28 at 21:00
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    @pkout, I don't think you can get mortar or much cement paste in those tiny holes. I anticipate it crumbling and falling out of there. Silicone is probably the best tool assuming that you're covering it with trim again.
    – popham
    Jan 28 at 21:05
  • I was able to push mortar down the other holes when working on another window, but i don't know if i was able to really fill it.
    – pkout
    Jan 28 at 21:25
  • And to make sure I understand you. You are saying that the brown coat and scratch coat are the same material. The scratch coat is just textured and painted, right?
    – pkout
    Jan 28 at 21:27
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    @pkout, close enough. Technically, different mortar may be used for the finish coat. And I would bet that there exist professionals who insist on different products for the scratch versus brown coats.
    – popham
    Jan 28 at 21:47

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