Chimney top installation process

The chimney top or cap allows smoke to exit the chimney but doesn’t allow small animals such as squirrels, birds and bats to enter the chimney. Also, rain water is blocked from entering the chimney.

Tools and materials

  • Drill
  • Masonry bit
  • Tapcon screws
  • Chimney top
  • Heat and water resistant silicone
  • Phillips head screwdriver


Your concrete chimney might have an exposed metal flue, in which case you must purchase tapcons to anchor the chimney cap.

Drill the concrete using a masonry bit. You can use silicone to add extra protection. Make sure it’s heat ratingĀ  is at least 1500 degrees and is waterproof if you choose to use it.


Make sure to protect yourself with heavy leather gloves when working with the chimney cap because it is usually made of sheet metal that has though and sharp corners.

Chimney cap type

The chimney comes in two designs. One that fits on the outside of the chimney flue and one that fits on the inside of the chimney flue. The first design is more common.

External chimney caps

To install an external chimney cap you must place it over the chimney flue so that it fully covers it. Then, you must use 8 self tapping metal screws to tightly secure the cap to the flue. You can use a strip of heat and water resistant silicone on the bottom gap to add more protection. A chimney with a hidden metal flue requires drilling with a masonry but before you can complete the process as for an exposed chimney flue.

Internal chimney cap

Slide the chimney cap on the chimney flue. Make sure it is tightly fit and apply heat resistant and water resistant silicone to the flue edge.

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