Frog of Bricks : The depression provided in the face of brick during its manufacturing is known as frog of bricks.
If the bricks are laid according to British standards, the frog should be laid upward and filled with mortar.
British Standard Code of Practice BS 5628-3 states. “Unless otherwise advised, lay single frog bricks with frog uppermost and double frogged with deeper frog uppermost. Fill all frogs with mortar…” This maximizes strength, stability and general performance of the brickwork.
Why frog should be laid upwards:
When the frog is laid upwards, the load is evenly spread throughout the width of the brick all the way down to the foundations. If the frog is laid down, the load is forced to the outsides of the brick.
The figure shown below can tell how the load is evenly spread and how it is forced to the outsides of brick.
Each horizontal layer of bricks laid in mortar in any brick work is called coarse.
The recommended maximum number of brickwork courses to lay in a day is 16.
Mortar placed horizontally below or on the top of a brick is called a bed. Mortar placed vertically between bricks is called a perpend.