I recently vented about a new home I had the pleasure of inspecting here in Salem, Oregon. That home had some issues with a lack of vapor retarder and a lot of excess wood that was a big contributor to a advanced stage of current fungal rot.
The home also had issues with lack of crawlspace ventilation. In this climate ventilation of the unfinished areas (attic and crawlspace) is extremely important. Moisture vapor that escapes the vapor retarder will rise and condense into liquid water if not allowed to ventilate and escape the confines of the crawlspace or attic. All of this moist wood is a perfect feeding buffet for wood destroying organisms.
The lack of ventilation under this doomed home was a big contributing factor to the deterioration. This was just one more issue that the contractors that built/poured the foundation neglected. All of these seemingly insignificant issues added up to a major repair bill in this new home's future.
That home was just one example of the issues that can plague new homes. Most people realize older homes should be inspected however most also think a new home doesn't need an inspection. Regardless of the age of the home you should always protect yourself with a licensed, certified, professional private home inspection.