The above image is taken from the NHBC 2018 guidelines and relates to the areas of the UK exposed to wind-driven rain. This is important to factor in when snagging new-build houses to ensure adequate protection from penetrating moisture.
Brickwork is porous, meaning rainwater in abundance will penetrate through it into the cavity so it is important on exposed walls that the water is allowed to escape through weep holes. Often we find they are blocked or not there at all, as shown in a couple of screenshots from recent inspections below:
