The Crown (sometimes inappropriately referred to as the cap) is a concrete slab that should be poured at the top on all chimneys. When pouring a new crown, the old mortar wash/crown needs to be completely removed and a new crown should be formed and poured so that it over-hangs all brick/stone on all sides of the chimney. Many chimneys in our area were built with just a “mortar wash” to save time and money during construction. The masons would take the left over mortar and smear it over the top of the chimney.
While this would last until the one year construction warranty was up, they will eventually crack and start to allow water to penetrate into the chimney. The end result is major deterioration to brick/stone chimneys, as well as water leaks inside the home. THE MOST IMPORTANT PART OF YOUR CHIMNEY IS A PROPERLY CONSTRUCTED OVER-HANGING CONCRETE CROWN.