Brick previously repaired with portland base mortar

                                              Click on photo to enlarge

Portland cement has a much higher compressive strength then the original brick and  lime mortar causing brick to crack. Portland cement is virtually waterproof, which does not allow water to escape or evaporate through the joints. The harmful salts contained in Portland cement cause damage by recrystallizing inside the adjacent soft brick. Spalling, cracking and disintegrating bricks are the result of irreversible damage caused by repairs conducted with improper selection of restoration mortars. 

Parging over the brick edges not only looks bad but it exacerbates the problem of water retention within the walls. 

Tar, caulking and silicone seldom found on poorly repaired chimneys not only will not do the job, but it will also cause irreversible damage by trapping water and moisture inside the highly porous historic brick and the entire masonry structures. 

© Fabio Bardini 2012|| (978) 825-9922