I have a sunroom on my home where the builder, Richmond America, used MDF with no flashing at the top of the 1x6 boards to prevent water from seeping down into the inside walls. We footed an expensive bill, so I had to ask a question to the pro's if this is a common issue? And,what other actions should I take to ensure other poor workmanship doesn't appear anywhere else around the home? I attached a photo of reference, thanks a bunch.