How to Fix a Bulging Chimney

Find out what causes a bulging chimney and how to fix it. When the chimney is inside a wall, you have two different types of framing material that are going to move at different rates and speeds. To rebuild that section of the wall, break out the old bulged plaster, and then very easily and gently refill the area with plaster of Paris until you get a nice, flat surface. Sand it, prime it and paint it.