How to Build a Fireplace

1. Locate the Fireplace

   Locate the fireplace above or near a grounded 120V outlet. Avoid areas of direct sunlight as the faux flame will wash out in bright light. If the fireplace insert has a heater, consider whether or not you want to locate the fireplace under a TV.

2. Remove the Baseboard

   With a prybar, remove the baseboard from the wall.

3. Size the Fireplace Insert Mounting Frame

   You'll use two-by-sixes a build a frame to hold the fireplace insert within the fireplace wall. The frame's inside dimensions should match the size of the fireplace insert's rough opening dimensions, with 1/8-inch extra on all sides. The fireplace insert's instructions should list rough opening dimensions.

   The mounting frame will be made of two-by-sixes, one at the top and one at the bottom and two on the sides. The length of each horizontal piece should equal the width of the insert, plus 3-1/4 inches. The two vertical two-by-sixes (left and light) should be the stated rough dimension height plus 1/4-inch.

   For example, if the instructions' stated rough dimensions are 18 inches high by 36 inches wide. Cut two boards to 39-1/4 inches each and two boards to 18-1/4 inches each.

4. Build the Fireplace Insert Mounting Frame

   With the drill and using 3-inch screws, build the fireplace insert mounting frame. Be precise when attaching the boards to keep the frame square. Test the size by slipping the fireplace insert into the frame.

5. Calculate the Fireplace Wall Height

   Because the fireplace wall will be built on the ground and then tilted up, height is a concern. Tilt-up walls cannot be as tall as the room's ceiling height. Reduce the height by 2 inches to allow for the height of the wall as it's being tilted up.

   As an example, the ceiling is 90 inches high. Subtract 3 inches to allow for the top and bottom horizontal two-by-sixes. Subtract another 2 inches so that the wall can be tilted up. So, the vertical two-by-sixes should be cut to 85 inches long.

6. Build the Fireplace Wall

   Construct the fireplace wall from seven vertical two-by-sizes placed between two 8-foot-long horizontal two-by-sixes, much like an ordinary wall system. Space the studs every 16 inches, on-center. Use two screws per attachment point.

   Tip

   The two-by-sixes' 5-1/2-inch depth is sufficient for many electric fireplace inserts. Be sure to check your own insert for size and venting requirements.

7. Attach the Mounting Frame to the Fireplace Wall

   Lay the mounting frame on top of the fireplace wall and center it. Choose a height that is visually appealing but also one that is close enough to the outlet for the fireplace insert to plug in.

   Mark the vertical studs that will need to be cut. Remove the mounting frame. Continue the mark downward with the Speed Square. Cut on the lines with a hand saw. Insert the mounting frame. Attach the mounting frame to the studs by screwing through the inside of the mounting frame.

8. Block the Studs

   Cut four two-by-sixes, each piece at 14-1/2 inches long. Add these four pieces between the studs, flat and flush with the back of the wall, to help attach the fireplace wall to the house's wall. Have two blocks below the fireplace insert mounting frame and another two blocks above it. Screw the blocks into place through the studs.

9. Attach the Fireplace Wall to the Room Wall

   With an assistant, tilt the fireplace wall up so it is vertical. Move it into place against the wall. Make sure that the outlet will be between two of the studs and will not be covered up by any of the studs. With the stud finder, locate wall studs (of the house) behind the stud blocks installed earlier. Use 3-inch screws to attach the fireplace wall.

10. Add the Cement Board to the Fireplace Wall

    Screw the cement board onto the studs of the hollow wall. Be sure to sink the heads of the screws. All vertical edges should land on a stud. Tape all seams with cement board tape. Mix up a small amount of mortar. Using the trowel, cover the tape with mortar.

    Tip

    Cement board can be added directly to studs with no sheathing or support as long as the studs are 16 inches on-center and 1/2-inch cement board is used.

11. Install the Fireplace Insert in the Fireplace Wall

    Plug in the fireplace insert. Slide it into the mounting frame. Before attaching the insert to the frame, hold a sample piece of veneer on the cement board next to the fireplace insert. The fireplace insert should match the edge of the stone veneer, plus another 1/4-inch to account for mortar. Attach the fireplace insert per the manufacturer's instructions.

12. Attach the Brick or Stone to the Fireplace Wall

    Cut a 1-inch strip of cardboard and band the perimeter of the fireplace insert with it to protect the insert.

    Create a dry layout of the stone veneer on the floor next to the fireplace wall.

    Cut as much of the stone veneer as possible beforehand. Use a wet tile saw to cut the veneer.

    Mix the stone veneer mortar with water in the 5-gallon bucket.

    Apply mortar to the cement board, plus butter the back of each stone before applying it to the wall.

    Maintain a 1/8-inch gap along the floor and walls.

    At the top, extend the top row of veneer stones 1/4- to 1/2-inch above the top edge of the fireplace wall to cover the edge.

    Upon completion, remove the protective strip from the fireplace.

    Tip

    Matching outer-corner veneer stones can often be purchased separately. These speed up the veneering process and produce cleaner corners.

When to Call a Professional

Some fireplace inserts may need to be hard-wired into the home's electrical system rather than using a cord that plugs into an outlet. If this is the case, hire a qualified, licensed electrician to wire the fireplace directly into an electrical box in accordance with local codes.