How to Install a Wood Firebox in a Corner

Position the firebox in the corner. Mount it on a flat, hard, non-combustible surface such as brick. Make sure the surface supports the unit at all four corners. If you have combustible flooring such as carpet or tile, place a metal panel on top. Extend the panel the entire depth and length of the firebox unit.

Check the clearance requirement for the firebox from the top of the unit to the ceiling, front and sides. Consult the installation manual and local building codes for exact specifications. Place the carpenter's level on the top surface of the firebox to check the level. Level the firebox with wood shims.

Install the chimney for the firebox. Use double wall galvanized steel pipe purchased from a fireplace or heating supply vendor. The larger outer pipe encases a smaller diameter pipe. Determine a route for the pipe that is free of obstructions, such as plumbing pipes or electrical wiring.

Trace the diameter of the chimney pipe on the interior side roof sheathing. Cut the opening, slightly larger than the pipe’s diameter, between two rafters. Use a reciprocating saw, which will cut through wood and the roof covering.

Follow the stove manufacturer’s instruction for connecting the chimney pipe to the firebox. Stack the pipes by inserting the end of one pipe into the end of another pipe. Use a counter clockwise twisting motion to lock the pipe sections together.

Insert a fire stop spacer where pipe penetrates the ceiling. The fire stop spacer protects combustible ceiling material from hot pipes and helps contain a fire between spaces. Follow the instructions for fitting the spacer on the joists. Fit the spacer on the top side of the joists if an attic exists above the ceiling. Secure the spacer on the underside if the area above the ceiling consists of living space. Screw the spacer to the joists.

Terminate the end of the chimney pipe a minimum of three feet from where the pipe penetrates the roof and 24 inches higher than the roof's peak, or per local code. Apply a storm collar with metal flashing around the opening. Slide the upper edge and sides of the flashing underneath the roof shingles. Hammer roofing nails along the top and side edges of the flashing. Apply roofing mastic around the edges of the flashing. Cover the nails with mastic to ensure a watertight roof.

Install the roof termination cap on the end of the pipe. The cap prevents snow and cold from blowing back down into the chimney pipe. Secure the cap to the pipe with three sheet metal screws.

Disconnect the power supply at the main electrical panel before starting any electrical wiring, if applicable. Some fireboxes have an optional blower unit. Wire the blower in accordance with the wiring instructions diagram in the instruction manual.