Hey everyone. 

I am currently working on my tiny house build. The dimensions are 34 by 9.5 with 14 foot ceilings. Siding and exterior is pretty much done.  I am about to close up walls after electrical is finished. Looking for some guidance as to which direction to go navigating potential humidity and mold issues since it seems choice in materials and strategy here might be key. 

I’ve noticed on the interior of some of the sheathing 11/32 inch ply from Home Depot, there are some mold spots  ( I think)  I have posted pictures.  Looking at old photos these spots have been there for months now  I guess I just didn’t noticed  the sheathing probably got a little wet in some areas during the build.  I would say over 99 % of the sheathing is fine, but these spots generally appear near the cross member galvanized steel framing and some at the sill plate.  Seems like mold becasue when I sprayed with vinegar and water the spots actually spread and changed in there appearance a day later.  I live in Hawaii, in a very damp location.  The house will not have a/c.  Trying to maintain a low humidity level with a dehumidifier is a little crazy since the air outside is literally like a cloud most times but we also get a lot of sun so things dry.  I have aluminum siding followed by tyvek then the sheathing fastened to my metal studs. 

so my questions are related to what would be the best way to proceed before closing in walls and also best choices for interior walls as well as best practices to keep humidity down / air flowing well in this kind of environment. Currently I am spot  treating all problem areas with vinegar then a mold killing primer.  I was going to go with a thin finished ply and then lime wash paint on interior walls but now not so sure.  Wondering on some insights as to best choices for interior wall and insulation in this environment.  Maybe cedar?  The drywall paper here tends to mold big time, special drywall? Plaster?  Weight is a bit of a consideration as the home is on a trailer.  

thanks for any guidance and insight, I just want a healthy home for years to come! 

I’ll post photos below.