Over the last 6months, I’ve had to take out and rebuild an area of my house, which also included taking out my drop in fireplace. The fireplace is back in, and while I wait for the weather to warm enough to put the chimney back, I’m considering replaceing the chimney cap. The old chimney cap is square and yet the chimney is round, so as well as not looking exactly right, makes me concerned that it is properly protecting the chimney.
In designing the new chimney cap, Im concerned about my design being a) wide enough and b) tall enough to allow the smoke to exit without hindrance. (See crude drawing below – yes, I know it looks like a hamburger, but it’s pretty close to what I need for a chimney cap…) The chimney is a triple wall chimney with the outer wall being 18 inches in diameter at the outer wall.
Does anyone know of any size constraints for either the distance of the overhang “A” or the height of the mesh area “B”? I am considering a 21 inch overall width which would give me only a 1.5 inch overhang, with an opening (the mesh height) of 4 – 6 inches. That said, does anyone know of any codes or needs I”m not addressing here? Should i consider perhaps making it closer to 24″ across? Taller?