This is not a tool shed but no other place to post. large gap. Suggestions?

beautiful building.

Was this to enable ventilation ? Otherwise why were the vertical wall panels not run farther . Perforated foam or vented soffit metal would allow it to breathe keep our birds and hornets etc !

Agree with ssewalk, seal it up too tight and it'll be an oven in the summer and a major rust magnet for everything inside the other three seasons.