We had a 2019 Bailey Alu tech van. Leaked like a sieve through the roof strap. A known fault in Baileys that was alleged to have been sorted prior to the manufacture of our year’s model. I beg to differ. Took months and months to get the part because of successive lockdowns. Fortunately the owner of the site where we had a seasonal pitch put it under cover in a barn, otherwise it would have been an indoor swimming pool. Got it eventually fixed, and then a few months later, woke up to water dripping on my face. The roof light above the bed leaking +++
Sold it back to the dealer for what we had paid for it.
As others have said there are points where one bit has to join to another bit, and these are the weak points. However this does not necessarily mean that they are worse than other vans.
mel