I don't get to work on older houses very often, but I have to help out a relative in Southern California.
I want to mount an electrical panel and some conduit on an outside wall of my Aunt's house. The house was build perhaps 85 years ago. The outside finish looks a little like stucco, but it is smoother and much harder. Could it be a concrete surface finish?
I don't know what the outside surface depth is. The inside of the wall is wood studs (back when 2 x 4's were really 2" by 4", with lathe and plaster on the inside surface. I want to use unistrut for mounting the panel and some of the larger conduit; perhaps a different style of mounting for anchoring the smaller conduit.
I am thinking I should anchor into studs. Maybe I can use a stud finder to map out stud lines on the outside.
There has been no outside maintenance for perhaps 15 years. I wonder if these walls become porous to rain if not painted periodically.
Can anyone tell me how residential house walls were build around the 1920's? And what best practices would be for mounting on these walls and weather-proofing them?