This photo shows a good example of a historic damp-proof course in brickwork.
This house was built about 110 years ago. A piece of slate tile was installed between the mortar joints of the lower course of brick. Here in this picture you can see where we picked away at the loose mortar. Over time, the mortar was not tuck pointed, and therefore, the mortar at this location is loose and deteriorating.
When we checked the condition of the mortar, we found this piece of slate tile shown in the picture. The slate tile was installed to provide a damp-proof course. Essentially, the slate tile is impermeable to moisture. The slate tile at this location is almost exactly the same as a slate tile on a roof.
The damp-proof course prevents or deters rising damp (moisture) from affecting and deteriorating the upper portions of the wall.
Click here to learn more about rising damp.