The hearth in a chimney is the floor part where fire is lit. This sometimes is made to project beyond the line of the structure. It can be sank into or made flush with the floor finishes. This should be made to contain the ash from burned out fires. The fire place is constructed with a fire back material that cannot burn. This also should apply to the chimney floor as hot ash will be resting on it until it is removed. It can also have a mesh sieve with a tray for holding the ash as fires burn.
When designing a fireplace, the hearth can be made to store firewood. This can be done by raising the chimney floor with a slab. The space between the hearth and floor can then be used to store wood. This usually works well in split level units. This is when the lounge is sunk and the dining higher. This enables the chimney to be built in between thus having a storage space below. Due to the amount of ash generated, it should be contained within so that it does not over flow into the other floor finishes.
The hearth is constructed during the chimney erection. This is finished during or after the normal floor finishes. It can however be redesigned in an existing fireplace in a home. The construction commences by starting with the fire back walls. This are the sloped walls inside the chimney visible from outside. They are designed to radiate the heat back into the room. They are chamfered on the sides. They tend to narrow towards the inside of the chimney. The bricks are the conventional material used in hearth and fire back construction.
The hearth floor is done with bricks laid half or full with the perforated side on the ends. They can also be laid normally but the holes have to be filled with concrete. The edge is usually done with a brick kerb of four or five inches in height above finished floor level. The thickness is usually three or four inches wide. It can be made square, rectangular or an arched shape. This is to contain the ash and fire debris inside. The kerb is then lined with a skirting finish to match the the rest of the room.