We have a 75 yr old home my grandparents built. House is in excellent shape and built very well.Triple brick in
basement and double brick in rest of house. Originally painted with oil base paint. All room have been converted to latex over past 20 yrs. Were primed with oil base primer before using latex. No problems with paint until about 3 yrs ago. Paint on 1 exterior wall bubbled up.. We sc****d paint off down to bare plaster, primed with oil base primer and repainted. Now it has happened again, same room, same wall. also in upstairs hallway. How do you fix it???????