Roof leaks are not limited to any one brand, price or style of RV. A determining factor could be which assembly employee went out drinking and came to work fuzzy the day yours came through the line. Just hope it wasn't the caulker in your case.
RV manufacturers give you a one year warranty--just long enough to rot the thing out and be noticed 13 months later. Then they tell you it is a lack of maintenance issue on your part.
2004 Damon Daybreak 2960F
05 Honda Element LX
In a democracy two wolves and a sheep can vote on what to have for dinner.
Not every manufacturer has a one year warranty. Jayco and Komfort have 2 and surely there are some others.
Checking the roof seams for cracks in the calking is part of proper trailer maintenence and should be done at least every spring and fall. Some builders do a better job then others, but even the best sometimes will develop a crack in the calking over time. Komfort and possibly some others actually pressure test every unit before it leaves the factory. This is an excellent way to check for leaks and some dealers have the ability to perform this test as a preventative measure.
Remember that these trailers move, flex and bounce along some pretty bad roads over time. Shocks and the Equa-flex links help also.