Chimney Repairs: Replace Crumbling Tuckpointing

The sight of crumbling mortar is often a tell tale sign that you need to add chimney repairs to your to-do list. Replacing the old and damaged mortar is called repointing or tuckpointing and is vital to maintaining your chimney. In most cases, this occurs towards the top of the chimney so you’ll need to be comfortable working on a ladder and your roof if you want to tackle this repair.

 You’ll need the following tools and equipment to perform these chimney repairs:

  • 4-inch grinder with tuckpointing blade
  • Hammer
  • Masonry Chisel
  • Square Masons Trowel
  • Pointing Trowel
  • Safety Glasses
  • Gloves
  • Extension Ladder

Step 1 – Remove the Old Mortar

The first step in this chimney repair is to remove the old crumbling mortar from the joints. Depending on the number of joints that are affected you may want to consider using a 4-inch angle grinder with a masonry blade. Simply run the grinder along the affected joints to remove the old mortar. You can use a hammer and masonry chisel to get to the hard-to-reach areas. If you’re only repairing a small area, you can forgo the grinder and just use a hammer and chisel. Whichever method you use, it’s important to completely remove all the old mortar in order for the new mortar to properly bond to the brick.

Step 2 – Install the New Mortar

The first step is to mix a batch of mortar in accordance with the manufacturer’s instructions on the bag. It’s best to mix the mortar in a wheelbarrow, if possible, and then transfer it to a 5-gallon bucket to make it easier to work with. Make sure you follow the instructions closely as mortar with too little or too much water will deteriorate rather quickly.

Once the mortar is mixed, load up the square mason's trowel with a comfortable amount of mortar. Place the trowel under the affected mortar joint and use the pointing trowel to push the mortar all the way into the joint. It’s important to pack the joint all the way to maintain the strength of the brick coursing. Repeat the process along all the affected joints until you’ve covered all the entire area you’re working on.

Step 3 – Striking the Mortar Joints

The last step is to use the jointing tool to finish off the new mortar joints. This process, often referred to as striking, gives the joints their familiar look and also helps keep water from pooling on the mortar. Run the striking tool along the vertical and horizontal joints while applying gentle pressure. The idea is to form a concave joint by gently scraping out the excess mortar. Work both the horizontal and vertical joints at the same time as you progress up the chimney wall and remove a little mortar at a time.

This is one of the more complicated chimney repairs a homeowner can tackle so take pride in a job well done.