DIY Network

How to Install a Gas Fireplace

Installing a gas fireplace in your family room will add warmth and interest to the space.

More in Electrical

  • Time

    Two Days

  • Price Range

    $1,000 - $2,500

  • Difficulty

    Moderate to Hard


Step 1: Prep the Space

Score the window molding with a matte knife. Remove the molding with a hammer and pry bar.

Remove the storm window from the outside of the house, followed by the windows glass pane. Unscrew and remove the frame. If the window being removed is a replacement window, take the old wooden window frame out so that the remaining gap can be framed.

If the existing studs of the wall are inset, you may need to insert a trimmed-to-size 2x4 as these pieces will act as nailers, filling up the gaps so a new frame can be attached.

Step 2: Create the Frame and Add Insulation

Create the frame by measuring and cutting out 2x4s and nailing them into place. Once the frame is constructed, cut a sheet of plywood to cover the opening of the old window and nail from the exterior.

To avoid drafts, gently insert fiberglass insulation around the old opening. Keep in mind insulation needs a certain amount of airspace around its fibers to work properly, so do not to pack it in too tightly. Cover the entire area with protective plastic to act as a vapor barrier.

Step 3: Attach the Plates

Attach the top and base plates to the existing ceiling and floor. Building codes dictate studs must be 16" on center, meaning the center of each stud is placed 16" apart. As with many old houses, the walls and ceiling may not be square, so measure out each stud separately to ensure correct length and subsequent fit.

Use a chop saw to cut the studs to size, fit into place, level, and attach with a framing nailer to the top and base plates, shooting nails in at an angle.

Step 4: Install the Drywall

Measure and cut the drywall to length and use 1-5/8" screws to attach it to the studs. Make custom cuts as necessary to ensure a clean fit. Stagger the joints of the drywall to help strengthen it and achieve a more professional finished look.

Tip: Leave a 1/2" gap between the floor and the bottom of the drywall to allow for the natural expansion and contraction of the drywall through the seasons.

Step 5: Build the Fireplace Frame

Use 2x4s and a framing nailer to build the fireplace frame to fit the dimensions of the fireplace. Have a plumber check the gas line for safety and connect it to the fireplace. Screw the facing into the framing.

Attach plywood with 1-5/8" screws to the framing around the fireplace to create the base for the stone façade. Measure and cut heavy-gauge tar paper and attach it to the plywood with a staple hammer.

Step 6: Apply the Mortar, and Place the Stones

Apply even coats of the mortar slightly thicker than the metal lath.

Tip: A good way to check the thickness is to scoop the mortar up on the trowel, shake off the excess, then turn it upside down. If there's too much on the trowel, it will fall off.

Use the mortar to coat (or "butter") the edges of the stone. Make sure the edges have more mortar on them than the center of the stone to create a vacuum that will help keep the stones in place.

Starting at the center, place the stones randomly for a natural look. Once in place, give a gentle tap to secure. Use a tile saw to cut the stones to fit as you go. Allow 24 hours to dry and set before applying the grout.