subject: Repairing A Masonry Chimney [print this page] There are a number of things that can go wrong with masonry chimneys, but the good news is that all of these problems can be solved if you contact the right professional. Here's a brief summary of the major issues that come up with masonry chimneys.
Cap problemsThe top of a masonry chimney typically has a concrete cap that slopes down from one or more ceramic liners that extend up through the center of the chimney. Over time, cracks will form in the concrete, and they are certain to grow larger if water enters them and then freezes. Patching mortar can be used to fill these cracks, but if the concrete starts to crumble or the cracks become too numerous, it's best to have the loose and deteriorated concrete removed so that a new cap can be installed.
Settling and shifting A masonry chimney requires a foundation, just like a house. But the importance of this small foundation is sometimes overlooked as the construction crew focuses on the larger one. It's not uncommon for a chimney foundation to be poorly made. If it's too small to support the chimney or located above the frost line, there's a good chance that soil movement might cause the chimney to tilt out of plumb. The right person to call for this type of repair is a foundation repair contractor.
Deteriorated mortar Even when correctly mixed and applied, the mortar used to lay up a brick chimney can deteriorate over time. If this problem is caught early enough, a mason can simply repoint the mortar joints to make the chimney look like new again.
Masonry cracks Most cracks in a masonry chimney occur in the mortar joints that separate bricks, blocks or stones. Hairline cracks don't indicate structural problems and can usually be ignored until the chimney is repointed. But if a crack is wider than 1/8 in. or if it varies in width, this can indicate a structural issue that should be investigated by an experienced mason or foundation repair contractor.
Flashing leaks Flashing is required where a chimney joins the roof of a house. When properly installed, chimney flashing protects the house and the chimney from water damage. Flashing can lose its effectiveness when new roofing is installed, when mortar joints deteriorate, and when a chimney shifts or settles. Because moisture can cause mold as well as structural damage, leaky flashing should be repaired right away.
