Once that mix gets soaked by November rain, you essentially have a wet sponge sitting hard against your lower bracket fixings. Unless those bottom reveals are detailed to pop off for a pressure-wash wand twice a year, that trapped damp never really dries out.

Our 15 mm baffle gap on a lab in Leiden did the exact same thing with midge swarms off the canal every August. You can model boundary layers down to the micron, but nature always treats a tight tolerance as prime real estate.

Any gap between 15 and 25 millimeters is prime nesting real estate, wind models be damned. If that bottom return doesn't unclip or drop on a hinge for a wash-down, you’ve basically detailed a vertical terrarium.

Ecology always takes over where the modeling stops. We had a shadow gap on a timber soffit in Paisley turn into high-density housing for pipistrelle bats before practical completion was even signed.

Accidental diffusion layer. I bet the raking light through all that backlit silk and willow fluff looked stunning before maintenance got to it.