How do dry leaves get involved in causing a leaky ceiling?

Not many? Almost none?

Something involving weird 3rd-floor gutters or eaves?

Someone on the 4th floor flushing dry leaves down a drain (cleaning something covered in dry leaves that got washed into a drain and clogged it?), leading to some bizarre overflow in a pipe between floors, thence to a 4th floor tub or sink, spilling onto the floor and seeping down through the 3rd floor ceiling?

What are you talking about?

What are you talking about?

I agree @Zaku !

Ten causes of a leaky roof
Leaves are a build up of debris. Number 1 thing on the linked list.

Oh wait you said 3rd floor of a building not a roof. Leaves shouldn’t be involved in that case.I don’t know how it starts. Cracks? Building gets old?

The op should distinguish between a leaky ceiling and a leaky roof.

Yes, if dry leaves get on or above the sixth floor of a building, they will cause a leaky ceiling between the third and fourth floor due to flooding on the fourth floor. It is because the dry leaves on the roof hold the water inside the building.

@Yellowdog You mean the leaves are in the gutter, so they get inside the siding in the walls? Or they flood into the 6th floor, which seeps down from floor to floor till it reaches the floor flo was asking about?

GRAVITY! This is another of those loopy questions that I studiously avoid. There is only ONE cause for a ceiling leak that matters, and that cause is simply an accumulation of water on the floor above. The pointless request for a list of methods to apply the water renders the question too silly to trouble with.

^^^ Say what?

They get sucked into it.

@Zaku I was referring to what is known as the “leaky jar” effect, where dry leaves or soft foam flakes on top of a building 6–10 stories will cause flooding on the floor in the middle of the height of a building, and thus, leak through the floor into the ceiling beneath it.

I know it doesn’t make a lot of sense, but its kind of like that first time when Legionaire’s Disease first broke out at the American Legion convention in Philadelphia in July 1976, due to water standing in the air conditioner ductwork that was comprised of a certain type of nickle alloy. Regular asprin in the water negated the effect

I’ll have to stop pursuing this, it’s too hard to understand.

@Yellowdog By what path and mechanism? Through a ventilation system?

… the ventilation system could be involved?

I was just conjecturing based on Yellowdog’s suggestion. I can imagine that being a possibility, or seeping down through the siding or something, but I haven’t found any references to dry leaves on a roof being an issue, and “leaky jar” searches only turn up actual literal leaky jar info, or an unrelated metaphor by Socrates the ancient Greek philosopher.

Yes, Socrates is the one who first postulated on this phenomenon.