We bought our house in southwest Ohio in October '07, and have since had a couple of conversations with neighbors in which they mention that they're preparing to treat the parts of their home exteriors that are stone. To avoid the risk of looking ignorant, I pretended that I knew what they were talking about, and just sort of nodded in agreement. (I know, I know.) What were they talking about? My home's exterior is entirely covered with stone (see pic); if should be treated or cleaned regularly, I'd like to know. The house was one-owner, built in '58. Could someone please let me know if I should be performing some sort of routine maintenance on the house? Thank you!