John Kogel Posted March 19, 2015 Report Share Posted March 19, 2015 I've seen this and repaired one with mortar once. The masonry flue is supporting the concrete crown. The chimney is straight and on a concrete footing. Bit of a creek behind the house, but a dry crawl. This is an extreme case, and I would like to understand better what has happened. Built in '88. Click to Enlarge 87.77 KB Click to Enlarge 75.77 KB Click to Enlarge 69.5 KB Click to Enlarge 50.82 KB Click to Enlarge 62.23 KB Quote Link to comment Share on other sites More sharing options...
mjr6550 Posted March 19, 2015 Report Share Posted March 19, 2015 Fired clay products like brick and flue liners expand as they absorb water. Concrete based products like block shrink as they cure. If the crown is bonded to the flue liner movement cannot occur so a mortar joint gives way. I have seen this even on chimneys that were never used. Quote Link to comment Share on other sites More sharing options...
Trent Tarter Posted March 19, 2015 Report Share Posted March 19, 2015 I would speculate that water has leaked below crown and freeze-thaw cycles have lifted it up. Quote Link to comment Share on other sites More sharing options...
inspector57 Posted March 19, 2015 Report Share Posted March 19, 2015 Is it not required to use a flexible sealant between the clay liner and crown? I assume the crown is not allowed to remain attached to the chimney structure due to being bonded to the liner which has expanded in relation to the chimney structure. Click to Enlarge 70.61 KB Quote Link to comment Share on other sites More sharing options...
Charlie R Posted March 19, 2015 Report Share Posted March 19, 2015 What is required and what the mason actually did are usually two different things. Like Mark wrote, the crown was sealed to the clay flue which lifted up due to expansion while the block of the chimney did not lift. I like how it actually broke the one block loose and lifted that block also. Good pics. Quote Link to comment Share on other sites More sharing options...
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