Stainless Steel Chimney Cowls
One of the most efficient steel chimney cowl designs is the "H-style" The H style is called this because it is shaped like the letter H, with a vertical pipe extending up from the chimney, a horizonal pipe attached on the top of that, and two short vertical pipes on either end of the horizontal pipe. These cowls can be made at home with duct tubing and a soldering iron, both of which can be found at home improvement stores.
The H-style is perfect for eliminating downdrafts.
Clay Chimney Cowls
For homeowners handy with clay, ceramic chimney cowls can be turned on a clay wheel. Clay chimney cowls have been popular for hundreds of years.
They can be sculpted in many different shapes. The shapes depend on the owner's preferences and reasons for using the cowl.
For example; those resembling the top of a bishop chess piece are best for blocking rain. Simple tapered cylinders with a piece of wire mesh across the top are best for keeping out animals.
Sheet Metal Chimney Cowl
Capped chimney cowls, those that look like they wear a hat, can be made from sheet metal. Homeowners can use aluminum or copper sheet metal to construct a homemade cowl.
Copper is known for being much more sturdy than aluminum, but it is also more expensive. A welding tool and a band saw is needed to construct the cowl from sheet metal, as well as a bracket system to install the finished cowl onto the chimney.
Found Object Chimney Cowl
Definitely the most homey of homemade chimney cowls, found objects can also be re-purposed to serve as chimney cowls. Even objects like stainless steel colanders can be used to protect the chimney opening from strong winds, rain and animals.
Other objects that can be re-purposed include steel buckets, chicken wire or clay flower pots.