My house (recent construction) has a single-piece bathtub in the upstairs bathroom - the kind that includes 3 walls surrounding it, I don't know if it's acrylic, glass-fiber, or some other construction.
Last week, an unnamed individual didn't properly close the shower curtain and never noticed while bathing, so the bathroom was flooded and water started dripping from the recessed lighting in the ceiling on the ground floor immediately below. I'd gauge at least a pint of water dripped from the light fixture - which I dutifully mopped up and put a bucket underneath - as well as immediately instructing the guilty individual to refrain from using that shower for a couple of days while I investigated.
(As far as I know the lights were/are fine: there was no electrical shorting or burning-smell afterwards).
I initially thought it was a burst shower or drain pipe, but after running the shower for testing there were no leaks downstairs, and I noticed water marks and warped paint on the baseboards - suggesting the cause was simply someone-not-closing-the-shower-curtain-properly - I also noticed a large gap between the baseboard and the bathtub unit that plenty of water on the floor could easily have escaped through.
As an aside, I'm surprised houses aren't designed for this eventuality by placing a giant drip-pan underneath each bathroom, such that all leaks are captured and can be sent via a pipe directly to the drains (the alternative being the "wet-room" concept, which I'm not a fan of).
Could any kind of lasting damage have been inflicted by this incident? Could the water have done anything to the structure? Are internal structural timbers usually waterproofed - or could this mean that the insides of my house will now rot and/or erode?
And are there any devices or things I could get that would detect if the floor is excessively wet and so alert the current bathroom user?
By way of mitigation, I've recently purchased a shower-curtain "curver" that ensures the curtain curves inward at the edges, rather than outward, so I hope that will help prevent a recurrence in future.