[teekert]

Same here. Especially that 2 year window... That was about when mold took over my bathroom. Then I wiped it all with Chlorine based cleaner, installed a duct with fan which works for up to 2 hours after detecting motion, made a grill in the door and there has been little to no mold since (in year 4 now).

But there may also be an element of insufficient building codes? Mold comes with poor (and inhomogeneous) heating, insufficient ventilation, bad moisture shielding (hot moist air should never enter and cool down in a building's structure), cold-bridges (not sure what the English term is for parts of a house significantly colder that other so moisture settles there). Ventilation holes should be well defined, and not via cracks that also let creatures in... Etc.

So it may not be all OP's fault. But it sure sounds like it.