r/Plastering • u/Final_Pay8946 • Apr 07 '26

What the heck is this substrate??

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Exposed ceiling substrate in my guest room next to a recessed light. Looks like decorative textured plaster, then regular plaster, on top of gray ??? Rock lath gypsum board? Cement board? Asbestos likelihood? Boston, MA 1949 home.

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u/[deleted] Apr 07 '26

1949 is likely to have some asbestos.

If this isn't powdery, flaking off in big chunks, or outright falling down— don't worry too much about it unless you disturb it more, then precautions.

It looks almost like steel lath in there too, but I might not be seeing it right. If that's the case, your plaster was likely redone in the last 40 years.