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Loose or missing chimney brick mortar
Jun 30, 2005

Question: I have some water damage to my kitchen ceiling. I had a new roof put on two years ago. Over the winter, I started noticing my kitchen ceiling starting to look like a road map and then by January it started to get worse and the paint peeled back and the bare drywall started to show. It even cracked around the chimney at the ceiling level as the chimney goes up through my kitchen.  What could have caused this problem?

Answer: The water damage could be be traced to your chimney.  Depending on how old your home is the problem may exist with the exterior bricks on the chimney. Exposure to the elements can over time cause brick to deteriorate. If the brickwork has loose or missing mortar, it needs your attention. Also, the face of the brick may be chipped, especially along the edges. 

Both the loose or missing mortar and chipping are due to exposure to the elements, especially during a freeze/thaw cycle. Brick chimneys are especially susceptible, mainly the part above the roof line where all four sides are exposed to the elements. Also, because of the heat inside the chimney during cold weather, condensation may occur on the inside of the chimney, especially between the chimney liner and the exterior bricks. Thus, moisture can damage the bricks from both inside and outside.

Some of the damage to a brick chimney will not be visible. If you suspect that you may have a “hidden” problem with your brick chimney, have a professional masonry contractor inspect the chimney.  Loose mortar falling down inside the chimney is a good indicator that you may have a problem.

Loose mortar is removed with a hammer and narrow chisel. The crevice is cleaned of all dust and dirt.Once loose mortar is removed and the area cleaned, fill in the space with a Redi-mixed mortar mixture of dry powder mixed with water. A bonding agent should be used and is mixed with the water before it is added to the powder. The bonding agent will increase the adhesion of the new mortar to the bricks.

Before the mortar is installed, wet the crevice with clear water. This will prevent the dry bricks from drawing the moisture from the mortar. The slower the mortar cures, the stronger it will be.

Installing mortar between the bricks and smoothing it is called “re-pointing.” Special narrow tools are used to install the mortar and to smooth it. Strike off any excess mortar from the brick face before it dries. If the surface of the bricks are stained, use a special Redi-mixed compound which is available from building supply stores.

Once your masonry contractor is finished, he will give you the details on what to look for in the future and, even though little maintenance is required, homeowners should watch for signs of deterioration and be quick to make repairs.