Had them out for an inspection after buying a house where the fireplace had clearly been used a lot and never maintained. He swept it, scoped the flue, and found a section of deteriorated mortar in the smoke chamber along with more buildup than I wanted to see. Parged the chamber, cleaned it out, and told me straight that the liner itself was fine and didn't need replacing. Draws properly now and I actually feel okay using it.

A chimney built in 1928 does not want to be repaired like one built in 2018 — and most of Whittier was built a lot closer to 1928.
Drive through Uptown, Hadley, or the streets below the hills and you're looking at unreinforced brick laid before seismic codes existed, in mortar soft enough to scratch with a coin. That masonry has since ridden out the 1987 Whittier Narrows earthquake, the 2008 Chino Hills quake, and every smaller shake between.
Damage from that history is rarely dramatic. It's a hairline stair-step crack running through the mortar joints, a quarter-inch gap where the stack meets the siding, a course of brick sitting slightly out of plumb above the roofline. From the ground it all looks fine. It usually isn't.






