By: Berlin On: Tue Nov 22, 2011 1:16 am
vertical cracks that travel through many courses are not great, but I believe that it's a combination of possible chimney fires that occurred long ago the house settling/shifting. I would guess that the floor joists box tightly around the stack and the foundation of the home has cracked/been repaired. This has applied some stresses to the stack over the years leading to those cracks. On your clay soil make sure that you have good drainage around your home, gutters/w/ downspouts and direct all water well away from the foundation. The basement and first floor cracks I am NOT worried about, they should still be sealed as good as possible with unsanded thinset/hydraulic cement. Where the old thimbles enter the stack at various locations they need to be removed and filled with either brick (chip the broken pieces out and insert new full bricks/w /mortar) or filled with a stiff mix of high strength concrete. If any of these thimbles are thickwall metal that would go a long way toward explaining your cracks (high rate of expansion pushes out on the stack around the thimble).
The area that definitely needs attention is the second floor where the left side of the stack has pulled away from itself. I'm not sure how accessible that will be, but you need to tear out the bricks and fix that entire area with new brick and type N mortar (softer mortar, don't use type S). In a perfect world I would apply quickrete's quickwall fiber reinforced surface bonding cement (available at lowes etc) to the entire exposed 1st and second floor chimney after all the other issues have been addressed. Although you might like the brick, this would go a long way toward adding significant strength to the structure.
