In 1946, a Norwegian came up with a secondary line of protection from rainwater. Until then, multi-wythe mass walls that had an absorption-storage-redistribution strategy for dealing with water. Each progressive layer of brick allowed only 1-10% of the water to pass though.

Both materials are porous and therefore wick or suck water. Small pores can suck water to a greater height than large pores. Materials with the tiniest pores suck the most. Did you know that concrete has very tiny pores?

Below grade leaks require 3 things:

1) Water

2) Hole

3) Force

Since at least Roman times, we have known to:

Open-joint cladding systems allow more water and air to enter behind the cladding than non open-joint cladding systems do. Turns out that open-joint cladding systems outperform non open-joint cladding systems BECAUSE they allow more air behind them.