Instructions for Step-by-Step Fireplace Construction

Open up the "builder's arch," which is a curved arch as wide as the central opening at the foot of the chimney breast and is usually built from brick in a herringbone pattern. Support the arch as you dismantle the bricks underneath it using a length of strong wood. Knock out stuck bricks using a mallet and chisel.

Chisel off jagged pieces of brick or stone from the walls. Remove lumps of stone or brick from the soil inside the opening. Dig out about half a foot of soil inside the opening so you can create a new floor for the fireplace using a spade or chisel. Wear thick gloves and a dust mask. Remove the debris, rubble and dust. Discard in a garbage can outside your home.

Apply fresh mortar to any gaps or small cracks in the chimney breast, arch or inside of the chimney using a trowel. Report large cracks to a structural surveyor and do not continue work until they have been resolved professionally. Allow fresh mortar to dry for at least two hours.

Have the chimney swept by a chimney sweep. Fit a cowl to the top where the chimney protrudes through the roof to prevent birds nesting inside, which will ruin your fires by preventing the direct passage of smoke. Install a flue liner from top to bottom to improve the chimney's efficiency.

Insulate the side and back walls using fireproof insulation board, such as cement backer board, which can be less than 1 inch thick, according to Ezi Board. Choose a board that can adhere to masonry substrates.

Build new brick walls along both sides and the back of the opening. Fix the bricks together and to the insulation board using fire-resistant cement, also called "refractory" cement, which is bought as a powder and is mixed with water to form a thick paste before application.

Lay a hearth on a bed of concrete. Make the hearth 5 inches thick to support the weight of the fire surround, as described by Solid Fuel. Make the hearth from brick or stone. Remember, stone will be more expensive and needs wet cutting by a professional mason. Speak to the mason about the dimensions of the opening and the size of fireplace you want. Level the hearth using a spirit level and mallet.

Fix dressed stone side panels to the fascia of the existing brickwork at either side of the arched opening to create your "surround," which is simply an attractive addition to the fascia, mounted on the front of the brickwork. Remember, fireplace surrounds are not structurally supportive, but improve the overall effect and make your work look more professional. For a stone fireplace, choose stone to form the surround. Ensure the stone is tightly adhered to the existing side walls and on top of the hearth using refractory grade concrete. Level each piece of stone using the spirit level. Tap uneven sections lightly with a mallet.

Opt for a less expensive brick surround by building a simple brick fascia with two sides and a "lintel," which is a single, supportive beam that runs the width of the opening and is supported on the two side walls. Install a steel beam for larger fireplaces for extra strength.

Finally, rest the "mantel" in place on top of the stone surround. The mantel is another decorative piece of stone, usually carved (also referred to as "dressed" stone) that sits on top of the two walls of the surround and finishes the fireplace. Be careful when lifting the mantel because it can be very heavy. Ask for assistance if you need it.