Vent hole in compression ribs

[Xavier]

Just a little guessing here :Many boxed wooden part in the wings have a little vent/drain hole to allow water to drain but also (I guess) to avoid too much pressure differences between the sealed inside and the outside.So what about some compression ribs that are completely sheeted both sides, clear coated inside and outside (Pitts' upper N°7 for exemple) ? Isn't there any need for vent holes in them ? I know it's not on the plans but I was wondering whether it could be a common practice that I wasn't aware of ...
Xav

 

[Neil]

 

[Xavier]

 

[bf92]

 

[John Burnett]

 

[Xavier]

 

[kjkimball]

 

[Neil]