Lime render or cement-based?

[Robert M]

Hello, how do I find out if the interior walls of my basement are plastered with lime plaster or cement-based plaster?

The house was built in 1956, it's likely the original plaster is still there.

Surely you should use lime plaster if it was used previously? Does it matter if you use lime plaster if it was cement-based before?

Best regards,
Robert

 

[imported_Byggaren]

Do not make the same mistake as the restoration workers did with the Visby city wall. They used cement-based plaster for pointing the wall made of limestone. Everything deteriorated, and they were then forced to remove the cement plaster and re-point with lime mortar.

If you have lime mortar, you should not use cement plaster. If you have cement plaster, you can use lime plaster, but it is not advisable. How to determine if it is one or the other can be judged by the color. Chip into the plaster a bit. If the surface is light or white, it is lime plaster. If it leans towards gray, it is cement plaster. (An old mason tests it with the tongue, but I have never managed to determine it that way.)
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The Builder