Is a Metal Flue Cap Good on a Chimney?

Advantages of Flue Caps

• Animals may seek the warmth provided by a fireplace or stove. Raccoons have been known to set up nests on the smoke shelf. Birds build nests in the chimney, causing blockages. Once many of these animals get into the chimney, they are unable to get back out. Hiring someone to remove them can be very expensive. The cap will also keep moisture from causing damage to the chimney. A cap protects the chimney crown by shedding moisture off, keeping it from being damaged by freezing water. Chimney caps also improve the draft from the chimney.

Disadvantages of Flue Caps

• Sometimes chimney caps cause a reduction in the draft capability of the fireplace or stove. Screen cap screens must be kept clear of creosote and soot buildup. If installed incorrectly they will also restrict the drafting ability. Burning unseasoned or green wood can cause tar and creosote to build up on the cap, which will then run down the outside of the chimney, causing a discoloration on the bricks and mortar. If you live in an area that is subject to high winds, a cap that is improperly attached may blow off.

Types of Flue Caps

• Stainless steel caps are affordable and are resistant to rust. Galvanized caps are also economical but frequently require a new coat of paint. If gas logs are used, the exhaust will corrode galvanized caps. Copper caps are more expensive but will resist corrosion caused by gas logs. Newer chimney caps are outfitted with damper systems. While they are more costly, closing the damper when the fire is out will prevent a loss of energy from your home.

Installation Tips

• Wear thick protective gloves when handling the chimney caps. Sharp edges on the sheet metal could cause serious cuts. Follow the manufacturer's instructions for installation of the cap. Do not use silicone sealant if you have a metal flue. The metal will get so hot that the sealant will be ruined and run down the chimney.