NEW trailer?
Somebody has cut an access for repairs of some sort.
Cutting a three sided window is normal to facilitate repairs with an enclosed belly.
The mfg. or dealer may have done this..........more than likely the dealership.
New.....take it back to them and have them replace the section of coroplast sheeting OR properly seal the windows.
Repairs were necessary but they didn't finish the job correctly.
I have two windows due to a slide out repair.
I glued some 1" X 3" wood strips to inside edges then screwed the flap to the wood, caulked it and then after caulking dried I used gorilla tape over the edges. (Need to clean it with alcohol so that the material is clean and dry for tape to properly stick and stay stuck)
