I have a home that was built in 1886, no drywall used here. The wall I'm concerned with is just to the left of the back door. The wall begain to bulge in areas and in an attempt to rectify the problem I hammered out an area of about 12" X 9" only to find slats of wood covered by lumber with the aluminum siding on the exterior. I started by putting a mesh in then applying the plaster, however it is not drying an d the area that has dried is cracking. Any advice?? Can I hammer out more of the wall & try to fit it with drywall?? Thanks for your help.