Firebrick is not installed directly on the firebox floor. It should be laid across the fireplace opening, but never directly over a gas or wood burner. The brick needs to have enough room so it cannot crush under its weight when placed in an upright position as well as space for airflow beneath them for ventilation and heating purposes.
– Start by placing pieces of broken bricks along each side of the fireplace opening that are also touching one another to form a level surface if possible. You can use mortar between these first pieces to give your structure added support until you reach desired height with other bricks – Ensure there is no gap left underneath!
– Continue stacking courses until reaching top course where any mantel will go (if applicable).
– When working with brick it helps to have a hammer and wire brush handy. The ends of broken bricks are often sharp so you’ll want to go over them until they’re smooth before stacking, plus it’s always good practice when installing any brick or stone work in your home!