Above, deteriorated chimney crown. Below, the same
chimney after the crown has been relaid.
Your chimney mortar crown is the sloped layer of mortar on top of your chimney. A properly sloped mortar crown causes rain run off of the chimney, helping to prevent absorption of moisture into your chimney. If the side of the chimney looks wet after a rain, if you see water in your fireplace or on the face wall around your fireplace inside, the trouble could be your mortar crown.
Once the mortar crown has deteriorated, the chimney
starts to fall apart and will
need to be rebuilt
Over the years, due to freeze/thaw cycles, the hot summer sun and simple deterioration of this mortar will begin to crack. Once a crack appears, this leaves a crevice that allows water to seep into your masonry chimney. Left untended, more moisture enters, more cracks appear, and the mortar crown can actually flake and chip off. You may see water dripping inside of your fireplace, or perhaps on the face wall around your fireplace opening.
At this stage of disrepair, your brick chimney will deteriorate quickly. Next, the mortar holding the bricks together deteriorates. Then the bricks at the top of the chimney come loose, and can fall onto your roof or even in your yard (perhaps on top of your car or whoever is standing on your deck). By this stage, rebuilding the top of the chimney becomes necessary.
How do you know if your mortar crown is in good condition? You can get on your roof and take a look at it, or call me for an inspection.
HOW WE FIX IT
Minor cracks in the mortar crown can be covered with a special sealant. However, if major cracking or chipping has already occurred, the old mortar is completely removed. Any loose bricks are re-set and tuckpointed, then a new mortar crown is laid, including the crown coat sealant that will make the chimney crown better than new.