Chimney
This step was something that I also did with the help of a friend. My friend Wes was a mason for 15 years. He agreed to help me if I helped him when needed. A trade in work as you will. Yeah buddy I know I still owe you some work. My fireplace is gas and vents out the side of my house but I figured I would mention it. If you are installing a real wood fireplace then its time to start on the chimney. Same with installing a prefab fireplace with a flue that sticks out roof. You will want your chimney built before your shingles are installed on roof. This will allow a correct installation of the metal flashing that goes around the chimney for waterproofing.
