Lintels
There are a few types of lintel you can get, depending on where and how you use them, from prestressed concrete and cavity lintels.
The main use of lintels is to bridge the gap between the cavity where the wall would be weakened by the gap and the weight above the lintel is spread over the length of the lintel. There is need for a minimum of 150mm overlap either side of the wall. cavity lintels are designed to carry any water in the cavity, to the outside skin through weep holes.