The Clicking Bathroom

[anaxcrosswords]

I kid you not.
My apartment is on the first floor of a 3-storey block, thus my bathroom is immediately below that of the apartment above. The apartments were built and kitted out pretty much the same, so each has a push-button (electric? Not sure) WC and an extractor fan.
Whether it comes from the fan or WC I can't know, but activity in the bathroom above results in a loud ticking/knocking noise which carries through the ceiling. It starts with maybe one tick per second then gradually slows down to one every 20-30 seconds before it stops, the whole sequence taking perhaps two minutes.
I really can't think of what might cause it. Any suggestions?

[Old_Geezer]

Sure it's not a drip ? What makes you think it's electrical in origin if it's not your bathroom to investigate ?

[anaxcrosswords]

No, it's definitely not a drip - just not that sort of sound. It's actually a difficult sound to describe. I suppose the nearest might be the sort of ticking sound you get as a heating device cools down after being switched off.

[Hopkirk]

Probably pipes expanding and then contracting as hot water passes along.

The clicking may be as they move in their fixings.

[KJN]

Agree with Hopkirk, have had the same problem for years , learnt to live with it, comes in handy, dont need an alarm clock in the mornings.

[The Builder]

It does sound like thermal expansion/contraction in the pipework/joists.

There should be much better sound insulation though.
How old are the apartments?

[anaxcrosswords]

Built about 10 years ago... on the cheap, methinks!

[The Builder]

Even 10 years ago, there should have been much better separation than that.

I'm afraid there's nothing you can do unless you get at the pipework by cutting an access hole in your ceiling. Just poor construction I guess.