No, this doesn’t involve trench coats.

A look at any older house quickly reveals the downside of older wooden exteriors.  Anything flat that can collect water will eventually experience dry rot, and anywhere that water can get to, it will, and will cause dry rot.

To avoid this, any flat surfaces, or anywhere that water might intrude, are flashed with metal flashing.  Here are some examples.

Incidentally, the term dry rot is an unfortunate one.  Dry rot is caused by varieties of fungi which feed on the wood, but require a certain amount of moisture to thrive.  So dry rot is actually moist rot.