How to Repair a Stone Chimney

A stone chimney is a great looking, as well as a comforting feature for most homes, modern or old. While it has an everlasting appeal, sometimes it can be tricky as well, owing to damage on the body that need to be fixed. While calling a professional repair expert burns a hole in the pocket, you can repair a stone chimney all by yourself over a weekend, and save on costs.

Tools and Materials Needed:

  • Stick
  • Chimney Cap
  • Wire Mesh
  • Screws
  • Screwdriver
  • Caulk
  • Hammer
  • Chisel
  • Thinset Mortar
  • Trowel
  • Brush

Step 1: Removing Blocks

Over time, small rock particles or debris may accumulate in the chimney, causing blockage in its flue. At times rodents and birds find shelter in the chimney tops. For such problems, you need to check your chimney at regular intervals, and clean the blocks using a long stick that can penetrate deep into the chimney. Poke it in the areas where any debris has collected. Use a ladder and place it on your roof against the chimney funnel, so that you can peep in through the chimney outlet from the outside.

Step 2: Placing a Chimney Cap Fan

A chimney cap fan is attached to the flue of the chimney and helps prevent rainwater or rodents from finding their way into the chimney. Sometimes, a stone chimney fan gets damaged and must be newly placed again. Since stone chimneys have a round flue, the process is pretty easy. Simply align the cap against the flue and sink in the screws tightly in the positions of the holes. These caps are ready to fit, and can be purchased from any hardware store. Check for blocks in the air holes of the chimney. If so, clean them up before putting on the new cap.

Step 3: Repairing Caps

If your chimney cap has cracked only a little, then do not pull it out for replacement. Simply take some wire mesh of the size of the chimney opening and place it over this area. Seal it using some tape. Now take some caulk and apply it at the corners of the mesh you placed, for effective sealing. However, the mesh needs to be replaced at least once in a year, as it gets worn out soon. The mesh must be made of stainless steel, as it is rust proof and more durable than iron.

Step 4: Repairing Cracks

Stone chimneys crack or wear out, due to natural eroding processes. Clean up the cracked area and rid it of rock pieces. Mix some concrete bonding agent, like a mix of lime and cement with water, such that the consistency is not too tight or loose.  Now, take this up in a trowel, put it in the cracks and use a putty knife to even up the surface. This acts as filler and sealer that repairs cracks. Make sure that the cracks get filled up to a fair depth, and not merely on the surface.

Step 5: Crumbling Mortar

At places in a stone chimney, the mortar seems to come off. For such damage, you need to scrap off the remaining mortar in the affected portions using a chisel or hammer. Now, moisten the surface and apply some semi-flowy thinset mortar, mixed according to its package instructions, using a trowel. Clean up the excess mortar from the places using a brush. Sprinkle water on the mortared areas for the next 3 days, so that it sets firmly. Make sure that the stone chimney is checked for damage frequently, so that you locate minor problems before they become major ones.