Learn more about corbel out
Being an old form of architecture the corbel out has the purpose to support other structures on the wall. The original corbel out is made of stone and it is built into the wall, but today people prefer using imitations made of wood or plaster. The most found application for this piece is on stone fireplaces for the mantel.
First identify where you want the mantel to be situated and then put the stones of the fireplace together with mortar. Stop when you are a foot below the place.
To act like a corbel out you should choose two large identical stones. The shape should be rectangular and the size, twice as long as the wall.
Build around the two stones that you have to put in place leaving them out from the rest of the fireplace. Keep the stones at the same level and to keep the corbel in place a long stone on top of it. You can place the mantel over the stones once the mortar is dry.
If you are looking for other uses for the corbel out you can check old buildings where they are used to sustain a roof or large blocks of stone. In many homes they are used as decorative pieces.