Masonry Repair on Payson's Older Chimneys

Repointing means cutting out failed mortar joints and filling them with new mortar. On a chimney built in the last fifty years it is straightforward work. On the older masonry around Payson's original grid it is the point where a repair either preserves the chimney or ruins it, and the deciding factor is which bag the mortar came out of.

Soft brick, soft mortar, and a rule that gets ignored

Brick made before the modern era was fired at lower temperatures and is considerably softer and more porous than what comes off a pallet today. It was laid in lime mortar, which is softer still, and that was deliberate. The mortar is meant to be the sacrificial element. When the wall moves with temperature, or when water freezes inside it, the soft mortar gives and crumbles, and you repoint it. The brick survives.

Repoint that same wall with a modern high-portland mortar and you invert the relationship. The new joints are now harder than the brick around them. The wall still moves and water still freezes, but the mortar no longer yields, so the stress goes into the brick faces instead. They spall. Within a few winters the joints look perfect and the brick between them is falling apart, and at that point there is no repair short of replacing the units. This is well understood in masonry conservation and it is routinely ignored on residential work because the correct mortar costs more and takes longer to cure.

We test what we are working with before mixing anything. If the existing mortar crumbles under a screwdriver and the brick is soft to a scratch, the repair uses a lime-based mix matched to it, not a general-purpose bag.

Where these chimneys actually fail

Almost always at the top and almost always because of water. The crown, if there ever was a proper one, is often a thin skim of mortar that broke up decades ago. Beyond that, the top few courses take the most water and the most freezing, so the mortar there goes first, then the brick starts moving, and then the stack leans. Rebuilding the top several courses on a sound lower chimney is a common and sensible job, and it is far less expensive than people fear.

Where we will tell you not to spend

Some old chimneys are worth restoring and some are not. If a stack is no longer serving any appliance, is leaning, and is going to keep costing money, taking it down to the roofline and capping it properly is a legitimate answer and we will say so. If it is a feature of the house and the masonry below the roof is sound, restoring it properly is usually the better decision and we will say that instead.