I live mid-block (houses on both sides), in a 1906 city row house with brick basement walls and a cement floor. We never have water in the basement. We have dark spots that get lighter and darker but never 100% go away. They are clearly moisture that is coming up through the floor at certain places.
Tests have shown the cement is about 33% wet in those dark spots. They are all at the front of the house. Outside, the tiny front yard is field stone and slopes away from the house, so no water is getting down around the front foundation. In the back, the outside level matches the interior and there is no standing water there (and no dark spots at the back of the house anyway).
What is causing the dampness and what can I do to stop it…before I finish the basement as usable space?
Best Answer
I have had issues with small springs under slabs, yes the dark spot is moisture. The tough thing if it is always there most sealers need the pad to be dry to seal properly. I have had really good luck on several of my own homes with 2 part epoxy applying in late summer. The worst place I would pull gallons of water out of my dehumidifier, once coated with 2 part epoxy paint their was hardly any moisture in the air being removed. The concrete has a high ph so mold is usually not a problem but in an older home the ph may be low or ~8 (when fresh 12-15). But mold in not usually a problem on a clean pad.