Building scientists and exterior cladding suppliers have been preaching for years that water from wind-driven rain and snowmelt will inevitably get past and behind exterior claddings. So sidewall assemblies need to be built to manage and mitigate (rather than try to stop) that moisture to avoid expensive latent defects.
“Assembly” is the key term, reflecting a combination of components that work together to shed and remove incidental water and also vent and dry any moisture before it settles in the framing cavities and shows up as drywall stains—or worse.
Such an assembly, usually for brick or stucco claddings (which are more porous than lap siding options), typically calls for an airspace that passively desiccates moisture vapor while also providing a channel for water, with weep holes at or near the bottom. It’s a complex approach requiring attention to detail, but money better spent than on defending lawsuits.