Do It Yourself Corner Stone Fireplaces

Remove any baseboard or trim work along the floors and walls where you wish to install a fireplace. Place the prefabricated hearth in the corner and slide it up tight against the wall. The hearth has sufficient weight to stay in place by itself.

Place the firebox directly on top of the hearth. It will have a pipe opening on one side near the top. Slide that side up against the wall. Trace around the opening with chalk. Slide the firebox back into the center of the hearth, flush with the front of the hearth.

Cut the drawing out using a reciprocating saw; it's okay to cut the hole slightly bigger than the drawing. Cut all the way through the wall so that you can see outside through the hole.

Slide a 6-by-48-inch triple wall stovepipe through the hole in the wall and slip the end of it over the flange on the firebox.

Screw one 2-by-4-by-48-inch stud vertically to the wall to both outside corners of the hearth and screw them to the wall with a screw gun and 2-inch screws. Measure the distance between studs and the corner. Cut two 2-by-4's on a miter saw to that length.
Flush them with the top of the vertical studs. Measure, cut and then screw another 2-by-4 horizontally to the front of the frame.

Screw another 2-by-4 stud to the floor directly underneath the horizontal stud. The firebox and hearth should now be inside a frame.

Measure the vertical distance between the two studs. Cut two studs and place them on either side of the firebox six inches from either side of the firebox. Screw them to the top and bottom of the framework.

Place a 48-by-48-inch piece of plywood on top of the frame. Trace around the outside perimeter of the frame. Cut the tracing out with a jigsaw. Place the plywood on top the frame and nail it to the horizontal framework using a hammer and 1 1/4-inch nails.

Place plywood vertically on the front of the framework. Trace around it, and cut the pieces to form a front over the fireplace frame. Nail them on.

Cut sections of metal lathe with tin snips to cover the plywood framework. Nail the sections on using horseshoe nails.

Mix the mortar per the manufacturer's directions. Apply mortar to the wire lathe and each individual piece of flagstone rock as you fit each piece in succession until you have covered the framework with stone.

Place a 6-inch elbow on the end of the stovepipe that is extended outside. Run stove pipe straight up and at least 24-inches higher than the crown of the roof.
Secure it to the side of the house with large metal bands that are screwed to the outside of the house.