Chimney Mortar Problems to Watch For in Kansas City

If brick is going to fail somewhere on a Kansas City house, the chimney is usually where it shows up first. It stands up above the roof exposed to weather on all four sides, it takes the full brunt of our freeze-thaw winters, and it is the one part of the masonry most people never look at closely. By the time a chimney problem is obvious from the ground, the mortar has often been going for years. Here is what to watch for.

Why the chimney fails first

A chimney is the most exposed masonry on your whole house. The walls of your home get some shelter from the roof overhang and the ground, but the chimney sticks straight up into the weather with no protection on any side. Rain hits it, wind drives moisture into it, and up top it has a crown and flue that give water even more ways in. Every freeze-thaw cycle we get works on it harder than anywhere else on the house, so the chimney is the early warning system for the rest of your brick.

Crumbling and receding mortar joints

The first thing to look for is the mortar between the bricks. Healthy joints are firm and flush. Failing joints go soft, crumble when you scratch them, and recede back so the edges of the brick start to stand proud. Once the mortar is receding, water runs into the gaps instead of shedding off the face, and the deterioration speeds up. This is exactly what chimney tuckpointing addresses, grinding out the bad mortar and packing in fresh, before the brick itself is affected.

White staining and spalling brick

Two related signs tell you water is already moving through the masonry. White chalky staining, called efflorescence, is mineral salt left behind as water evaporates out of the brick, and it means moisture is getting in and passing through. Spalling is the next stage: the face of the brick flakes, pops, or crumbles off, usually because water soaked in and then froze and expanded. Spalled brick cannot be repaired, it has to be replaced, which is why catching the mortar problem first matters. See our brick repair page.

A cracked crown and loose caps

The crown is the sloped concrete or mortar cap on top of the chimney that sheds water away from the flue. It takes weather from directly above, and when it cracks, water pours straight down into the core of the chimney where you cannot see it doing damage. A cracked crown, a missing or rusted flashing joint where the chimney meets the roof, and a loose or absent flue cap are all ways water gets in from the top. Problems up there often explain mortar failure lower down.

A leaning or bowing chimney

The serious one is movement. If a chimney is leaning away from the house, bowing out on one face, or you can see a gap opening between the chimney and the wall, that is well past a mortar issue and into a structural one. It usually means water has been getting into the masonry for a long time and freeze-thaw has broken down the internal bond, or the footing has shifted. A leaning chimney needs attention promptly, because the failure mode is bricks coming down.

Frequently asked questions